Universe - Blog Posts

May the Four Forces Be With You!

May the force be with you? Much to learn you still have, padawan. In our universe it would be more appropriate to say, “May the four forces be with you.”

There are four fundamental forces that bind our universe and its building blocks together. Two of them are easy to spot — gravity keeps your feet on the ground while electromagnetism keeps your devices running. The other two are a little harder to see directly in everyday life, but without them, our universe would look a lot different!

Let’s explore these forces in a little more detail.

Gravity: Bringing the universe together

If you jump up, gravity brings you back down to Earth. It also keeps the solar system together … and our galaxy, and our local group of galaxies and our supercluster of galaxies.

Gravity pulls everything together. Everything, from the bright centers of the universe to the planets farthest from them. In fact, you (yes, you!) even exert a gravitational force on a galaxy far, far away. A tiny gravitational force, but a force nonetheless.

Credit: NASA and the Advanced Visualization Laboratory at the National Center for Supercomputing and B. O'Shea, M. Norman

Despite its well-known reputation, gravity is actually the weakest of the four forces. Its strength increases with the mass of the two objects involved. And its range is infinite, but the strength drops off as the square of the distance. If you and a friend measured your gravitational tug on each other and then doubled the distance between you, your new gravitational attraction would just be a quarter of what it was. So, you have to be really close together, or really big, or both, to exert a lot of gravity.

Even so, because its range is infinite, gravity is responsible for the formation of the largest structures in our universe! Planetary systems, galaxies and clusters of galaxies all formed because gravity brought them together.

Gravity truly surrounds us and binds us together.

Electromagnetism: Lighting the way

You know that shock you get on a dry day after shuffling across the carpet? The electricity that powers your television? The light that illuminates your room on a dark night? Those are all the work of electromagnetism. As the name implies, electromagnetism is the force that includes both electricity and magnetism.

Electromagnetism keeps electrons orbiting the nucleus at the center of atoms and allows chemical compounds to form (you know, the stuff that makes up us and everything around us). Electromagnetic waves are also known as light. Once started, an electromagnetic wave will travel at the speed of light until it interacts with something (like your eye) — so it will be there to light up the dark places.

Like gravity, electromagnetism works at infinite distances. And, also like gravity, the electromagnetic force between two objects falls as the square of their distance. However, unlike gravity, electromagnetism doesn't just attract. Whether it attracts or repels depends on the electric charge of the objects involved. Two negative charges or two positive charges repel each other; one of each, and they attract each other. Plus. Minus. A balance.

This is what happens with common household magnets. If you hold them with the same “poles” together, they resist each other. On the other hand, if you hold a magnet with opposite poles together — snap! — they’ll attract each other.

Electromagnetism might just explain the relationship between a certain scruffy-looking nerf-herder and a princess.

Strong Force: Building the building blocks

Credit: Lawrence Livermore National Laboratory

The strong force is where things get really small. So small, that you can’t see it at work directly. But don’t let your eyes deceive you. Despite acting only on short distances, the strong force holds together the building blocks of the atoms, which are, in turn, the building blocks of everything we see around us.

Like gravity, the strong force always attracts, but that’s really where their similarities end. As the name implies, the force is strong with the strong force. It is the strongest of the four forces. It brings together protons and neutrons to form the nucleus of atoms — it has to be stronger than electromagnetism to do it, since all those protons are positively charged. But not only that, the strong force holds together the quarks — even tinier particles — to form those very protons and neutrons.

However, the strong force only works on very, very, very small distances. How small? About the scale of a medium-sized atom’s nucleus. For those of you who like the numbers, that’s about 10-15 meters, or 0.000000000000001 meters. That’s about a hundred billion times smaller than the width of a human hair! Whew.

Its tiny scale is why you don’t directly see the strong force in your day-to-day life. Judge a force by its physical size, do you? 

Weak Force: Keeping us in sunshine

If you thought it was hard to see the strong force, the weak force works on even smaller scales — 1,000 times smaller. But it, too, is extremely important for life as we know it. In fact, the weak force plays a key role in keeping our Sun shining.

But what does the weak force do? Well … that requires getting a little into the weeds of particle physics. Here goes nothing! We mentioned quarks earlier — these are tiny particles that, among other things, make up protons and neutrons. There are six types of quarks, but the two that make up protons and neutrons are called up and down quarks. The weak force changes one quark type into another. This causes neutrons to decay into protons (or the other way around) while releasing electrons and ghostly particles called neutrinos.

So for example, the weak force can turn a down quark in a neutron into an up quark, which will turn that neutron into a proton. If that neutron is in an atom’s nucleus, the electric charge of the nucleus changes. That tiny change turns the atom into a different element! Such reactions are happening all the time in our Sun, giving it the energy to shine.

The weak force might just help to keep you in the (sun)light.

All four of these forces run strong in the universe. They flow between all things and keep our universe in balance. Without them, we’d be doomed. But these forces will be with you. Always.

You can learn more about gravity from NASA’s Space Place and follow NASAUniverse on Twitter or Facebook to learn about some of the cool cosmic objects we study with light.

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Swift: Our Sleuth for the Universe’s Gamma-ray Bursts

The universe is full of mysteries, and we continue to search for answers. How can we study matter and energy that we can’t see directly? What’s it like inside the crushed core of a massive dead star? And how do some of the most powerful explosions in the universe evolve and interact with their surrounding environment? 

Luckily for us, NASA’s Neil Gehrels Swift Observatory is watching the skies and helping astronomers answer that last question and more! As we celebrate its 15-year anniversary, let’s get you up to speed about Swift.

What are gamma-ray bursts and why are they interesting?

Gamma-ray bursts are the most powerful explosions in the universe. When they occur, they are about a million trillion times as bright as the Sun. But these bursts don’t last long — from a few milliseconds (we call those short duration bursts) to a few minutes (long duration). In the 1960s, spacecraft were watching for gamma rays from Earth — a sign of nuclear testing. What scientists discovered, however, were bursts of gamma rays coming from space!

Gamma-ray bursts eventually became one of the biggest mysteries in science. Scientists wanted to know: What events sparked these fleeting but powerful occurrences?

So how do gamma-ray bursts and Swift connect?

When it roared into space on a rocket, Swift’s main goals included understanding the origin of gamma-ray bursts, discovering if there were additional classes of bursts (besides the short and long ones), and figuring out what these events could tell us about the early universe.

With Swift as our eyes on the sky, we now know that gamma-ray bursts can be some of the farthest objects we’ve ever detected and lie in faraway galaxies. In fact, the closest known gamma-ray burst occurred more than 100 million light-years from us. We also know that these explosions are associated with some of the most dramatic events in our universe, like the collapse of a massive star or the merger of two neutron stars — the dense cores of collapsed stars.

Swift is still a powerful multiwavelength observatory and continues to help us solve mysteries about the universe. In 2018 it located a burst of light that was at least 10 times brighter than a typical supernova. Last year Swift, along with NASA’s Fermi Gamma-ray Space Telescope, announced the discovery of a pair of distant explosions which produced the highest-energy light yet seen from gamma-ray bursts.

Swift can even study much, much closer objects like comets and asteroids!

Why is Swift unique?

How do we study events that happen so fast? Swift is first on the scene because of its ability to automatically and quickly turn to investigate sudden and fascinating events in the cosmos. These qualities are particularly helpful in pinpointing and studying short-lived events.

The Burst Alert Telescope, which is one of Swift’s three instruments, leads the hunt for these explosions. It can see one-sixth of the entire sky at one time. Within 20 to 75 seconds of detecting a gamma-ray burst, Swift automatically rotates so that its X-ray and ultraviolet telescopes can view the burst.

Because of the “swiftness” of the satellite, it can look at a lot in 24 hours — between 50 and 100 targets each day! Swift has new “targets-of-opportunity” to look at every day and can also look at objects for follow up observations. By doing so, it can see how events in our cosmos change over time.

How did Swift get its name?

You may have noticed that lots of spacecraft have long names that we shorten to acronyms. However, this isn’t the case for Swift. It’s named after the bird of the same name, and because of the satellite’s ability to move quickly and re-point its science instruments.

When it launched, Swift was called NASA’s Swift Observatory. But in January 2018, Swift was renamed the Neil Gehrels Swift Observatory in memory of the mission’s original principal investigator, Neil Gehrels.

Follow along with Swift to see a typical day in the life of the satellite:

Sometimes... there’s more than meets the eye. 👀 You’re looking at two very different takes on an iconic image. ⁣

Human eyes can see only a small portion of the range of radiation given off by the objects around us. We call this wide array of radiation the electromagnetic spectrum, and the part we can see visible light.

In the first image, researchers revisited one of Hubble Space Telescope’s most popular sights: the Eagle Nebula’s Pillars of Creation. Here, the pillars are seen in infrared light, which pierces through obscuring dust and gas and unveil a more unfamiliar — but just as amazing — view of the pillars. ⁣ ⁣ The entire frame is peppered with bright stars and baby stars are revealed being formed within the pillars themselves. The image on the bottom is the pillars in visible light.

Image Credit: NASA, ESA/Hubble and the Hubble Heritage Team⁣

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The trickster “Blinking Planetary”

Planetary nebula NGC 6826 is located about 4,200 light years from Earth in Cygnus. When observers look directly at it through a small telescope, they typically see only the nebula’s sparkling-white central star. However, by averting one’s gaze, glancing away from the central star, the nebula’s bulbous dust clouds come into view. This optical trickery earned this planetary nebula the name the "Blinking Planetary.” 

Over the next several thousand years, the nebula will gradually disperse into space, and then the central star will slowly cool as it radiates its energy for billions of years as a white dwarf. 

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Even star systems have identity crises. 🤷⁣ ⁣ According to data from observatories like our @nasachandraxray, a double star system has been rapidly flipping between two alter egos: a low-mass X-ray binary and a millisecond pulsar. Astronomers found this volatile double system in a dense collection of stars known as Terzan 5.⁣ ⁣ The first image from @NASAHubble shows Terzan 5 in optical light. Swipe to see the new image where low, medium and high-energy X-rays detected by Chandra are colored red, green and blue respectively. Click the link in bio for more. ⁣ ⁣

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Need some space? We’ve got the job! 👨‍🚀👩‍🚀⁣

We’re accepting applications March 2-31 for the next class of #Artemis Generation astronauts who will embark on missions to the Moon and Mars. Join our class of star sailors and find out if you have what it takes to #BeAnAstronaut! 

The basic requirements to apply include United States citizenship and a master’s degree in a STEM field, including engineering, biological science, physical science, computer science, or mathematics, from an accredited institution. The requirement for the master’s degree can also be met by:

Two years (36 semester hours or 54 quarter hours) of work toward a Ph.D. program in a related science, technology, engineering or math field;

A completed doctor of medicine or doctor of osteopathic medicine degree;

Completion (or current enrollment that will result in completion by June 2021) of a nationally recognized test pilot school program.

Candidates also must have at least two years of related, progressively responsible professional experience, or at least 1,000 hours of pilot-in-command time in jet aircraft. Astronaut candidates must pass the NASA long-duration spaceflight physical.

More information here. 

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Celebrating Spitzer, One of NASA’s Great Observatories

As the Spitzer Space Telescope’s 16-year mission ends, we’re celebrating the legacy of our infrared explorer. It was one of four Great Observatories – powerful telescopes also including Hubble, Chandra and Compton – designed to observe the cosmos in different parts of the electromagnetic spectrum.

Light our eyes can see

The part of the spectrum we can see is called, predictably, visible light. But that’s just a small segment of all the wavelengths of the spectrum. The Hubble Space Telescope observes primarily in the visible spectrum. Our Chandra X-ray Observatory is designed to detect (you guessed it) X-ray emissions from very hot regions of the universe, like exploded stars and matter around black holes. Our Compton Gamma Ray Observatory, retired in 2000, produced the first all-sky survey in gamma rays, the most energetic and penetrating form of light.

Then there’s infrared…

Infrared radiation, or infrared light, is another type of energy that we can't see but can feel as heat. All objects in the universe emit some level of infrared radiation, whether they're hot or cold. Spitzer used its infrared instrument to make discoveries in our solar system (including Saturn's largest ring) all the way to the edge of the universe. From stars being born to planets beyond our solar system (like the seven Earth-size exoplanets around the star TRAPPIST-1), Spitzer's science discoveries will continue to inspire the world for years to come.

Multiple wavelengths

Together, the work of the Great Observatories gave us a more complete view and understanding of our universe.

Hubble and Chandra will continue exploring our universe, and next year they’ll be joined by an even more powerful observatory … the James Webb Space Telescope!

Many of Spitzer's breakthroughs will be studied more precisely with the Webb Space Telescope. Like Spitzer, Webb is specialized for infrared light. But with its giant gold-coated beryllium mirror and nine new technologies, Webb is about 1,000 times more powerful. The forthcoming telescope will be able to push Spitzer's science findings to new frontiers, from identifying chemicals in exoplanet atmospheres to locating some of the first galaxies to form after the Big Bang.

We can’t wait for another explorer to join our space telescope superteam!

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Are We Alone? How NASA Is Trying to Answer This Question.

One of the greatest mysteries that life on Earth holds is, “Are we alone?”

At NASA, we are working hard to answer this question. We’re scouring the universe, hunting down planets that could potentially support life. Thanks to ground-based and space-based telescopes, including Kepler and TESS, we’ve found more than 4,000 planets outside our solar system, which are called exoplanets. Our search for new planets is ongoing — but we’re also trying to identify which of the 4,000 already discovered could be habitable.

Unfortunately, we can’t see any of these planets up close. The closest exoplanet to our solar system orbits the closest star to Earth, Proxima Centauri, which is just over 4 light years away. With today’s technology, it would take a spacecraft 75,000 years to reach this planet, known as Proxima Centauri b.

How do we investigate a planet that we can’t see in detail and can’t get to? How do we figure out if it could support life?

This is where computer models come into play. First we take the information that we DO know about a far-off planet: its size, mass and distance from its star. Scientists can infer these things by watching the light from a star dip as a planet crosses in front of it, or by measuring the gravitational tugging on a star as a planet circles it.

We put these scant physical details into equations that comprise up to a million lines of computer code. The code instructs our Discover supercomputer to use our rules of nature to simulate global climate systems. Discover is made of thousands of computers packed in racks the size of vending machines that hum in a deafening chorus of data crunching. Day and night, they spit out 7 quadrillion calculations per second — and from those calculations, we paint a picture of an alien world.

While modeling work can’t tell us if any exoplanet is habitable or not, it can tell us whether a planet is in the range of candidates to follow up with more intensive observations. 

One major goal of simulating climates is to identify the most promising planets to turn to with future technology, like the James Webb Space Telescope, so that scientists can use limited and expensive telescope time most efficiently.

Additionally, these simulations are helping scientists create a catalog of potential chemical signatures that they might detect in the atmospheres of distant worlds. Having such a database to draw from will help them quickly determine the type of planet they’re looking at and decide whether to keep observing or turn their telescopes elsewhere.

Learn more about exoplanet exploration, here. 

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Neutron Stars Are Even Weirder Than We Thought

Let’s face it, it’s hard for rapidly-spinning, crushed cores of dead stars NOT to be weird. But we’re only beginning to understand how truly bizarre these objects — called neutron stars — are.

Neutron stars are the collapsed remains of massive stars that exploded as supernovae. In each explosion, the outer layers of the star are ejected into their surroundings. At the same time, the core collapses, smooshing more than the mass of our Sun into a sphere about as big as the island of Manhattan.

Our Neutron star Interior Composition Explorer (NICER) telescope on the International Space Station is working to discover the nature of neutron stars by studying a specific type, called pulsars. Some recent results from NICER are showing that we might have to update how we think about pulsars!

Here are some things we think we know about neutron stars:

Pulsars are rapidly spinning neutron stars ✔︎

Pulsars get their name because they emit beams of light that we see as flashes. Those beams sweep in and out of our view as the star rotates, like the rays from a lighthouse.

Pulsars can spin ludicrously fast. The fastest known pulsar spins 43,000 times every minute. That’s as fast as blender blades! Our Sun is a bit of a slowpoke compared to that — it takes about a month to spin around once.

The beams come from the poles of their strong magnetic fields ✔︎

Pulsars also have magnetic fields, like the Earth and Sun. But like everything else with pulsars, theirs are super-strength. The magnetic field on a typical pulsar is billions to trillions of times stronger than Earth’s!

Near the magnetic poles, the pulsar’s powerful magnetic field rips charged particles from its surface. Some of these particles follow the magnetic field. They then return to strike the pulsar, heating the surface and causing some of the sweeping beams we see.

The beams come from two hot spots… ❌❓✔︎ 🤷🏽

Think of the Earth’s magnetic field — there are two poles, the North Pole and the South Pole. That’s standard for a magnetic field.

On a pulsar, the spinning magnetic field attracts charged particles to the two poles. That means there should be two hot spots, one at the pulsar’s north magnetic pole and the other at its south magnetic pole.

This is where things start to get weird. Two groups mapped a pulsar, known as J0030, using NICER data. One group found that there were two hot spots, as we might have expected. The other group, though, found that their model worked a little better with three (3!) hot spots. Not two.

… that are circular … ❌❓✔︎ 🤷🏽

The particles that cause the hot spots follow the magnetic field lines to the surface. This means they are concentrated at each of the magnetic poles. We expect the magnetic field to appear nearly the same in any direction when viewed from one of the poles. Such symmetry would produce circular hot spots.

In mapping J0030, one group found that one of the hot spots was circular, as expected. But the second spot may be a crescent. The second team found its three spots worked best as ovals.

… and lie directly across from each other on the pulsar ❌❓✔︎ 🤷🏽

Think back to Earth’s magnetic field again. The two poles are on opposite sides of the Earth from each other. When astronomers first modeled pulsar magnetic fields, they made them similar to Earth’s. That is, the magnetic poles would lie at opposite sides of the pulsar.

Since the hot spots happen where the magnetic poles cross the surface of the pulsar, we would expect the beams of light to come from opposite sides of the pulsar.

But, when those groups mapped J0030, they found another surprising characteristic of the spots. All of the hot spots appear in the southern half of the pulsar, whether there were two or three of them.

This also means that the pulsar’s magnetic field is more complicated than our initial models!

J0030 is the first pulsar where we’ve mapped details of the heated regions on its surface. Will others have similarly bizarre-looking hotspots? Will they bring even more surprises? We’ll have to stay tuned to NICER find out!

And check out the video below for more about how this measurement was done.

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Celebrate #BlackHoleFriday with Nurturing Baby Stars

Are you throwing all your money into a black hole today?

Forget Black Friday — celebrate #BlackHoleFriday with us and get sucked into this recent discovery of a black hole that may have sparked star births across multiple galaxies.

If confirmed, this discovery would represent the widest reach ever seen for a black hole acting as a stellar kick-starter — enhancing star formation more than one million light-years away. (One light year is equal to 6 trillion miles.)

A black hole is an extremely dense object from which no light can escape. The black hole's immense gravity pulls in surrounding gas and dust. Sometimes, black holes hinder star birth. Sometimes — like perhaps in this case — they increase star birth.

Telescopes like our Chandra X-ray Observatory help us detect the X-rays produced by hot gas swirling around the black hole. Have more questions about black holes? Click here to learn more.

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Women in Exploration: From Human Computers to All-Woman Spacewalks

Since the 19th century, women have been making strides in areas like coding, computing, programming and space travel, despite the challenges they have faced. Sally Ride joined NASA in 1983 and five years later she became the first female American astronaut. Ride's accomplishments paved the way for the dozens of other women who became astronauts, and the hundreds of thousands more who pursued careers in science and technology. Just last week, we celebrated our very first #AllWomanSpacewalk with astronauts Christina Koch and Jessica Meir.

Here are just a couple of examples of pioneers who brought us to where we are today:

The Conquest of the Sound Barrier

Pearl Young was hired in 1922 by the National Advisory Committee for Aeronautics (NACA), NASA’s predecessor organization, to work at its Langley site in support in instrumentation, as one of the first women hired by the new agency. Women were also involved with the NACA at the Muroc site in California (now Armstrong Flight Research Center) to support flight research on advanced, high-speed aircraft. These women worked on the X-1 project, which became the first airplane to fly faster than the speed of sound. 

Young was the first woman hired as a technical employee and the second female physicist working for the federal government.

The Human Computers of Langley

The NACA hired five women in 1935 to form its first “computer pool”, because they were hardworking, “meticulous” and inexpensive. After the United States entered World War II, the NACA began actively recruiting similar types to meet the workload. These women did all the mathematical calculations – by hand – that desktop and mainframe computers do today.

Computers played a role in major projects ranging from World War II aircraft testing to transonic and supersonic flight research and the early space program. Women working as computers at Langley found that the job offered both challenges and opportunities. With limited options for promotion, computers had to prove that women could successfully do the work and then seek out their own opportunities for advancement.

Revolutionizing X-ray Astronomy

Marjorie Townsend was blazing trails from a very young age. She started college at age 15 and became the first woman to earn an engineering degree from the George Washington University when she graduated in 1951. At NASA, she became the first female spacecraft project manager, overseeing the development and 1970 launch of the UHURU satellite. The first satellite dedicated to x-ray astronomy, UHURU detected, surveyed and mapped celestial X-ray sources and gamma-ray emissions.

Women of Apollo

NASA’s mission to land a human on the Moon for the very first time took hundreds of thousands workers. These are some of the stories of the women who made our recent #Apollo50th anniversary possible:

• Margaret Hamilton led a NASA team of software engineers at the Massachusetts Institute of Technology and helped develop the flight software for NASA’s Apollo missions. She also coined the term “software engineering.” Her team’s groundbreaking work was perfect; there were no software glitches or bugs during the crewed Apollo missions. 

• JoAnn Morgan was the only woman working in Mission Control when the Apollo 11 mission launched. She later accomplished many NASA “firsts” for women:  NASA winner of a Sloan Fellowship, division chief, senior executive at the Kennedy Space Center and director of Safety and Mission Assurance at the agency.

• Judy Sullivan, was the first female engineer in the agency’s Spacecraft Operations organization, was the lead engineer for health and safety for Apollo 11, and the only woman helping Neil Armstrong suit up for flight.

Hidden Figures

Author Margot Lee Shetterly’s book – and subsequent movie – Hidden Figures, highlighted African-American women who provided instrumental support to the Apollo program, all behind the scenes.

• An alumna of the Langley computing pool, Mary Jackson was hired as the agency’s first African-American female engineer in 1958. She specialized in boundary layer effects on aerospace vehicles at supersonic speeds. 

• An extraordinarily gifted student, Katherine Johnson skipped several grades and attended high school at age 13 on the campus of a historically black college. Johnson calculated trajectories, launch windows and emergency backup return paths for many flights, including Apollo 11.

• Christine Darden served as a “computress” for eight years until she approached her supervisor to ask why men, with the same educational background as her (a master of science in applied mathematics), were being hired as engineers. Impressed by her skills, her supervisor transferred her to the engineering section, where she was one of few female aerospace engineers at NASA Langley during that time.

Lovelace’s Woman in Space Program

Geraldyn “Jerrie” Cobb was the among dozens of women recruited in 1960 by Dr. William Randolph "Randy" Lovelace II to undergo the same physical testing regimen used to help select NASA’s first astronauts as part of his privately funded Woman in Space Program.

Ultimately, thirteen women passed the same physical examinations that the Lovelace Foundation had developed for NASA’s astronaut selection process. They were: Jerrie Cobb, Myrtle "K" Cagle, Jan Dietrich, Marion Dietrich, Wally Funk, Jean Hixson, Irene Leverton, Sarah Gorelick, Jane B. Hart, Rhea Hurrle, Jerri Sloan, Gene Nora Stumbough, and Bernice Trimble Steadman. Though they were never officially affiliated with NASA, the media gave these women the unofficial nicknames “Fellow Lady Astronaut Trainees” and the “Mercury Thirteen.”

The First Woman on the Moon

The early space program inspired a generation of scientists and engineers. Now, as we embark on our Artemis program to return humanity to the lunar surface by 2024, we have the opportunity to inspire a whole new generation. The prospect of sending the first woman to the Moon is an opportunity to influence the next age of women explorers and achievers.

This material was adapted from a paper written by Shanessa Jackson (Stellar Solutions, Inc.), Dr. Patricia Knezek (NASA), Mrs. Denise Silimon-Hill (Stellar Solutions), and Ms. Alexandra Cross (Stellar Solutions) and submitted to the 2019 International Astronautical Congress (IAC). For more information about IAC and how you can get involved, click here.

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And that is a wrap!

Get sucked into the black hole excitement? Find out more about these unique objects and the missions we have to study them, here. 

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What is the most fascinating thing about black hole research for you, personally?

How does time work in a black hole?

Is it at all possible to send a drone into a black hole and collect the data of what it’s like inside? If not, how close do you we are to possibly achieving that?

uhmm, can you tell me what exactly a black hole is? or what iy does? thanks, just really confused and curious on how it actually works.

What would happen if I go into a black hole? Do you think I would disappear forever or would I still exist inside the black hole?

How Do You Solve a Problem Like Dark Energy?

Here’s the deal — the universe is expanding. Not only that, but it’s expanding faster and faster due to the presence of a mysterious substance scientists have named “dark energy.”

But before we get to dark energy, let’s first talk a bit about the expanding cosmos. It started with the big bang — when the universe started expanding from a hot, dense state about 13.8 billion years ago. Our universe has been getting bigger and bigger ever since. Nearly every galaxy we look at is zipping away from us, caught up in that expansion!

The expansion, though, is even weirder than you might imagine. Things aren’t actually moving away from each other. Instead, the space between them is getting larger.

Imagine that you and a friend were standing next to each other. Just standing there, but the floor between you was growing. You two aren’t technically moving, but you see each other moving away. That’s what’s happening with the galaxies (and everything else) in our cosmos ... in ALL directions!

Astronomers expected the expansion to slow down over time. Why? In a word: gravity. Anything that has mass or energy has gravity, and gravity tries to pull stuff together. Plus, it works over the longest distances. Even you, reading this, exert a gravitational tug on the farthest galaxy in the universe! It’s a tiny tug, but a tug nonetheless.

As the space between galaxies grows, gravity is trying to tug the galaxies back together — which should slow down the expansion. So, if we measure the distance of faraway galaxies over time, we should be able to detect if the universe's growth rate slows down.  

But in 1998, a group of astronomers measured the distance and velocity of a number of galaxies using bright, exploding stars as their “yardstick.” They found out that the expansion was getting faster.

Not slowing down.

Speeding up.

⬆️ This graphic illustrates the history of our expanding universe. We do see some slowing down of the expansion (the uphill part of the graph, where the roller coaster is slowing down). However, at some point, dark energy overtakes gravity and the expansion speeds up (the downhill on the graph). It’s like our universe is on a giant roller coaster ride, but we’re not sure how steep the hill is!

Other researchers also started looking for signs of accelerated expansion. And they found it — everywhere. They saw it when they looked at individual stars. They saw it in large scale structures of the universe, like galaxies, galaxy groups and clusters. They even saw it when they looked at the cosmic microwave background (that’s what’s in this image), a "baby picture" of the universe from just a few hundred thousand years after the big bang.

If you thought the roller coaster was wild, hold on because things are about to get really weird.

Clearly, we were missing something. Gravity wasn’t the biggest influence on matter and energy across the largest scales of the universe. Something else was. The name we’ve given to that “something else” is dark energy.

We don’t know exactly what dark energy is, and we’ve never detected it directly. But we do know there is a lot of it. A lot. If you summed up all the “stuff” in the universe — normal matter (the stuff we can touch or observe directly), dark matter, and dark energy — dark energy would make up more than two-thirds of what is out there.

That’s a lot of our universe to have escaped detection!

Researchers have come up with a few dark energy possibilities. Einstein discarded an idea from his theory of general relativity about an intrinsic property of space itself. It could be that this bit of theory got dark energy right after all. Perhaps instead there is some strange kind of energy-fluid that fills space. It could even be that we need to tweak Einstein’s theory of gravity to work at the largest scales.  

We’ll have to stay tuned as researchers work this out.

Our Wide Field Infrared Survey Telescope (WFIRST) — planned to launch in the mid-2020s — will be helping with the task of unraveling the mystery of dark energy. WFIRST will map the structure and distribution of matter throughout the cosmos and across cosmic time. It will also map the universe’s expansion and study galaxies from when the universe was a wee 2-billion-year-old up to today. Using these new data, researchers will learn more than we’ve ever known about dark energy. Perhaps even cracking open the case!

You can find out more about the history of dark energy and how a number of different pieces of observational evidence led to its discovery in our Cosmic Times series. And keep an eye on WFIRST to see how this mystery unfolds.

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Look! A cosmic block party 🥳 In this Hubble image, you’ll find 50 spiral and dwarf galaxies hanging out in our cosmic neighborhood. The main focal point of stars is actually a dwarf galaxy. Dwarf galaxies often show a hazy structure, an ill-defined shape and an appearance somewhat akin to a swarm or cloud of stars — and UGC 685 is no exception to this. These data were gathered under Hubble’s Legacy ExtraGalactic UV Survey (LEGUS) program, the sharpest and most comprehensive ultraviolet survey of star-forming galaxies in the nearby universe. Image Credit: ESA/Hubble & NASA; the LEGUS team, B. Tully, D. Calzetti

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Celebrating Women’s Equality Day Across NASA

August 26 is celebrated in the United States as Women’s Equality Day. On this day in 1920, the Nineteenth Amendment was signed into law and American women were granted the constitutional right to vote. The suffragists who fought hard for a woman’s right to vote opened up doors for trailblazers who have helped shape our story of spaceflight, research and discovery. On Women’s Equality Day, we celebrate women at NASA who have broken barriers, challenged stereotypes and paved the way for future generations. This list is by no means exhaustive. 

Rocket Girls and the Advent of the Space Age

In the earliest days of space exploration, most calculations for early space missions were done by “human computers,” and most of these computers were women. These women's calculations helped the U.S. launch its first satellite, Explorer 1. This image from 1953, five years before the launch of Explorer 1, shows some of those women on the campus of the Jet Propulsion Laboratory (JPL).

These women were trailblazers at a time when most technical fields were dominated by white men. Janez Lawson (seen in this photo), was the first African American hired into a technical position at JPL. Having graduated from UCLA with a bachelor's degree in chemical engineering, she later went on to have a successful career as a chemical engineer.

Katherine Johnson: A Champion for Women’s Equality

Mathematician Katherine Johnson, whose life story was told in the book and film "Hidden Figures," is 101 years old today! Coincidentally, Johnson’s birthday falls on August 26: which is appropriate, considering all the ways that she has stood for women’s equality at NASA and the country as a whole.

Johnson began her career in 1953 at the National Advisory Committee for Aeronautics (NACA), the agency that preceded NASA, one of a number of African-American women hired to work as "human computers.” Johnson became known for her training in geometry, her leadership and her inquisitive nature; she was the only woman at the time to be pulled from the computing pool to work with engineers on other programs.

Johnson was responsible for calculating the trajectory of the 1961 flight of Alan Shepard, the first American in space, as well as verifying the calculations made by electronic computers of John Glenn’s 1962 launch to orbit and the 1969 Apollo 11 trajectory to the moon. She was awarded the Presidential Medal of Freedom, the nation's highest civilian honor, by President Barack Obama on Nov. 24, 2015.

JoAnn Morgan: Rocket Fuel in Her Blood 

JoAnn Morgan was an engineer at Kennedy Space Center at a time when the launch room was crowded with men. In spite of working for all of the Mercury, Gemini and Apollo programs, and being promoted to a senior engineer, Morgan was still not permitted in the firing room at liftoff — until Apollo 11, when her supervisor advocated for her because of her superior communication skills. Because of this, Morgan was the instrumentation controller — and the only woman — in the launch room for the Apollo 11 liftoff. 

Morgan’s career at NASA spanned over 45 years, and she continued to break ceiling after ceiling for women involved with the space program. She excelled in many other roles, including deputy of Expendable Launch Vehicles, director of Payload Projects Management and director of Safety and Mission Assurance. She was one of the last two people who verified the space shuttle was ready to launch and the first woman at KSC to serve in an executive position, associate director of the center.

Oceola (Ocie) Hall: An Advocate for NASA Women 

Oceola Hall worked in NASA’s Office of Diversity and Equal Opportunity for over 25 years. She was NASA’s first agency-wide Federal Women’s program manager, from 1974 – 1978. Hall advanced opportunities for NASA women in science, engineering and administrative occupations. She was instrumental in initiating education programs for women, including the Simmons College Strategic Leadership for Women Program.

Hall’s outstanding leadership abilities and vast knowledge of equal employment laws culminated in her tenure as deputy associate administrator for Equal Opportunity Programs, a position she held for five years. Hall was one among the first African-American women to be appointed to the senior executive service of NASA. This photo was taken at Marshall during a Federal Women’s Week Luncheon on November 11, 1977 where Hall served as guest speaker.

Hall was known for saying, “You have to earn your wings every day.”

Sally Ride: Setting the Stage for Women in Space

The Astronaut Class of 1978, otherwise known as the “Thirty-Five New Guys,” was NASA’s first new group of astronauts since 1969. This class was notable for many reasons, including having the first African-American and first Asian-American astronauts and the first women.

Among the first women astronauts selected was Sally Ride. On June 18, 1983, Ride became the first American woman in space, when she launched with her four crewmates aboard the Space Shuttle Challenger on mission STS-7. On that day, Ride made history and paved the way for future explorers.

When those first six women joined the astronaut corps in 1978, they made up nearly 10 percent of the active astronaut corps. In the 40 years since that selection, NASA selected its first astronaut candidate class with equal numbers of women and men, and women now comprise 34 percent of the active astronauts at NASA.

Charlie Blackwell-Thompson: First Female Launch Director 

As a part of our Artemis missions to return humans to the Moon and prepare for journeys to Mars, the Space Launch System, or SLS, rocket will carry the Orion spacecraft on an important flight test. Veteran spaceflight engineer Charlie Blackwell-Thompson will helm the launch team at Kennedy Space Center in Florida. Her selection as launch director means she will be the first woman to oversee a NASA liftoff and launch team.

"A couple of firsts here all make me smile," Blackwell-Thompson said. "First launch director for the world's most powerful rocket — that's humbling. And I am honored to be the first female launch director at Kennedy Space Center. So many amazing women that have contributed to human space flight, and they blazed the trail for all of us.”

The Future of Women at NASA

In this image, NASA astronauts Anne McClain and Christina Koch pose for a portrait inside the Kibo laboratory module on the International Space Station. Both Expedition 59 flight engineers are members of NASA's 2013 class of astronauts.   

As we move forward as a space agency, embarking on future missions to the Moon, Mars and beyond, we reflect on the women who blazed the trail and broke glass ceilings. Without their perseverance and determination, we would not be where we are today.

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Say hello to the Butterfly Nebula 👋

It looks like our Hubble Space Telescope captured an image of a peaceful, cosmic butterfly unfurling its celestial wings, but the truth is vastly more violent. In the Butterfly Nebula, layers of gas are being ejected from a dying star. Medium-mass stars grow unstable as they run out of fuel, which leads them to blast tons of material out into space at speeds of over a million miles per hour!

Streams of intense ultraviolet radiation cause the cast-off material to glow, but eventually the nebula will fade and leave behind only a small stellar corpse called a white dwarf. Our middle-aged Sun can expect a similar fate once it runs out of fuel in about six billion years.

Planetary nebulas like this one aren’t actually related to planets; the term was coined by astronomer William Herschel, who actually discovered the Butterfly Nebula in 1826. Through his small telescope, planetary nebulas looked like glowing, planet-like orbs. While stars that generate planetary nebulas may have once had planets orbiting them, scientists expect that the fiery death throes these stars undergo will ultimately leave any planets in their vicinity completely uninhabitable.

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That star stuff you see here? That's what you're made of. You possess the elements ✨ ⁣

This composite image from our Chandra X-ray Observatory, the Spitzer Space Telescope and the Isaac Newton Telescope shows high-energy X-rays emitted by young, massive stars in the star cluster Cygnus OB2. This year we're celebrating the 20th anniversary of Chandra's launch. Want to dive deeper? Click here

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Five Record-Setting Gamma-ray Bursts!

For 10 years, our Fermi Gamma-ray Space Telescope has scanned the sky for gamma-ray bursts (GRBs), the universe’s most luminous explosions!

Most GRBs occur when some types of massive stars run out of fuel and collapse to create new black holes. Others happen when two neutron stars, superdense remnants of stellar explosions, merge. Both kinds of cataclysmic events create jets of particles that move near the speed of light.

A new catalog of the highest-energy blasts provides scientists with fresh insights into how they work. Below are five record-setting events from the catalog that have helped scientists learn more about GRBs:

1. Super-short burst in Boötes!

The short burst 081102B, which occurred in the constellation Boötes on Nov. 2, 2008, is the briefest LAT-detected GRB, lasting just one-tenth of a second!

2. Long-lived burst!

Long-lived burst 160623A, spotted on June 23, 2016, in the constellation Cygnus, kept shining for almost 10 hours at LAT energies — the longest burst in the catalog.

For both long and short bursts, the high-energy gamma-ray emission lasts longer than the low-energy emission and happens later.

3. Highest energy gamma-rays!

The highest-energy individual gamma ray detected by Fermi’s LAT reached 94 billion electron volts (GeV) and traveled 3.8 billion light-years from the constellation Leo. It was emitted by 130427A, which also holds the record for the most gamma rays — 17 — with energies above 10 GeV.

4. In a constellation far, far away!

The farthest known GRB occurred 12.2 billion light-years away in the constellation Carina. Called 080916C, researchers calculate the explosion contained the power of 9,000 supernovae.

5. Probing the physics of our cosmos!

The known distance to 090510 helped test Einstein’s theory that the fabric of space-time is smooth and continuous. Fermi detected both a high-energy and a low-energy gamma ray at nearly the same instant. Having traveled the same distance in the same amount of time, they showed that all light, no matter its energy, moves at the same speed through the vacuum of space.

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5 of Your Fermi Gamma-ray Space Telescope Questions Answered

The Fermi Gamma-ray Space Telescope is a satellite in low-Earth orbit that detects gamma rays from exotic objects like black holes, neutron stars and fast-moving jets of hot gas. For 11 years Fermi has seen some of the highest-energy bursts of light in the universe and is helping scientists understand where gamma rays come from.

Confused? Don’t be! We get a ton of questions about Fermi and figured we'd take a moment to answer a few of them here.

1. Who was this Fermi guy?

The Fermi telescope was named after Enrico Fermi in recognition of his work on how the tiny particles in space become accelerated by cosmic objects, which is crucial to understanding many of the objects that his namesake satellite studies.

Enrico Fermi was an Italian physicist and Nobel Prize winner (in 1938) who immigrated to the United States to be a professor of physics at Columbia University, later moving to the University of Chicago.

Original image courtesy Argonne National Laboratory

Over the course of his career, Fermi was involved in many scientific endeavors, including the Manhattan Project, quantum theory and nuclear and particle physics. He even engineered the first-ever atomic reactor in an abandoned squash court (squash is the older, English kind of racquetball) at the University of Chicago.

There are a number of other things named after Fermi, too: Fermilab, the Enrico Fermi Nuclear Generating Station, the Enrico Fermi Institute and more. (He’s kind of a big deal in the physics world.)

Fermi even had something to say about aliens! One day at lunch with his buddies, he wondered if extraterrestrial life existed outside our solar system, and if it did, why haven't we seen it yet? His short conversation with friends sparked decades of research into this idea and has become known as the Fermi Paradox — given the vastness of the universe, there is a high probability that alien civilizations exist out there, so they should have visited us by now.  

2. So, does the Fermi telescope look for extraterrestrial life?

No. Although both are named after Enrico Fermi, the Fermi telescope and the Fermi Paradox have nothing to do with one another.

Fermi does not look for aliens, extraterrestrial life or anything of the sort! If aliens were to come our way, Fermi would be no help in identifying them, and they might just slip right under Fermi’s nose. Unless, of course, those alien spacecraft were powered by processes that left behind traces of gamma rays.

Fermi detects gamma rays, the highest-energy form of light, which are often produced by events so far away the light can take billions of years to reach Earth. The satellite sees pulsars, active galaxies powered by supermassive black holes and the remnants of exploding stars. These are not your everyday stars, but the heavyweights of the universe. 

3. Does the telescope shoot gamma rays?

No. Fermi DETECTS gamma rays using its two instruments, the Large Area Telescope (LAT) and the Gamma-ray Burst Monitor (GBM).

The LAT sees about one-fifth of the sky at a time and records gamma rays that are millions of times more energetic than visible light. The GBM detects lower-energy emissions, which has helped it identify more than 2,000 gamma-ray bursts – energetic explosions in galaxies extremely far away.

The highest-energy gamma ray from a gamma-ray burst was detected by Fermi’s LAT, and traveled 3.8 billion light-years to reach us from the constellation Leo.

4. Will gamma rays turn me into a superhero?

Nope. In movies and comic books, the hero has a tragic backstory and a brush with death, only to rise out of some radioactive accident stronger and more powerful than before. In reality, that much radiation would be lethal.

In fact, as a form of radiation, gamma rays are dangerous for living cells. If you were hit with a huge amount of gamma radiation, it could be deadly — it certainly wouldn’t be the beginning of your superhero career.

5. That sounds bad…does that mean if a gamma-ray burst hit Earth, it would wipe out the planet and destroy us all?

Thankfully, our lovely planet has an amazing protector from gamma radiation: an atmosphere. That is why the Fermi telescope is in orbit; it’s easier to detect gamma rays in space!

Gamma-ray bursts are so far away that they pose no threat to Earth. Fermi sees gamma-ray bursts because the flash of gamma rays they release briefly outshines their entire home galaxies, and can sometimes outshine everything in the gamma-ray sky.

If a habitable planet were too close to one of these explosions, it is possible that the jet emerging from the explosion could wipe out all life on that planet. However, the probability is extremely low that a gamma-ray burst would happen close enough to Earth to cause harm. These events tend to occur in very distant galaxies, so we’re well out of reach.

We hope that this has helped to clear up a few misconceptions about the Fermi Gamma-ray Space Telescope. It’s a fantastic satellite, studying the craziest extragalactic events and looking for clues to unravel the mysteries of our universe!

Now that you know the basics, you probably want to learn more! Follow the Fermi Gamma-ray Space Telescope on Twitter (@NASAFermi) or Facebook (@nasafermi), and check out more awesome stuff on our Fermi webpage.

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Chandra X-Ray Observatory, We Appreciate You

On July 23, 1999, the Space Shuttle Columbia blasted off from the Kennedy Space Center carrying the Chandra X-ray Observatory. In the two decades that have passed, Chandra’s powerful and unique X-ray eyes have contributed to a revolution in our understanding of the cosmos.

Since its launch 20 years ago, Chandra's unrivaled X-ray vision has changed the way we see the universe.

Chandra has captured galaxy clusters – the largest gravitationally bound objects in the universe – in the process of merging.

Chandra has shown us the powerful wind and shock fronts that rumble through star-forming systems.

And a star school, so to speak -- home to thousands of the Milky Way's biggest and brightest.

Carl Sagan said, "We are made of star-stuff." It's true. Most of the elements necessary for life are forged inside stars and blasted into interstellar space by supernovas. Chandra has tracked them.

Thank you Chandra X-Ray! To more adventures with you!

Check out Chandra’s 20th anniversary page to see how they are celebrating.

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What Space Weather Means for You

In space, invisible, fast-moving particles from the Sun and other sources in deep space zip around, their behavior shaped by dynamic electric and magnetic fields. There are so few of these particles that space is considered a vacuum, but what’s there packs a punch. Together, we call all of this invisible activity space weather — and it affects our technology both in space and here on Earth.

This month, two new missions are launching to explore two different kinds of space weather.

Scrambled signals

Many of our communications and navigation systems — like GPS and radio — rely on satellites to transmit their signals. When signals are sent from satellites down to Earth, they pass through a dynamic zone on the upper edge of Earth's atmosphere called the ionosphere.

Gases in the ionosphere have been cooked into a sea of positive- and negative-charged particles by solar radiation. These electrically charged particles are also mixed in with neutral gases, like the air we breathe. The charged particles respond to electric and magnetic fields, meaning they react to space weather. Regular weather can also affect this part of the atmosphere.

Influenced by this complicated web of factors, structured bubbles of charged gas sometimes form in this part of the atmosphere, particularly near the equator. When signals pass through these bubbles, they can get distorted, causing failed communications or inaccurate GPS fixes.

Right now, it's hard to predict just when these bubbles will form or how they'll mess with signals. The two tiny satellites of the E-TBEx mission will try to shed some light on this question.

As these CubeSats fly around Earth, they'll send radio signals to receiving stations on the ground. Scientists will examine the signals received in order to see whether — and if so, how much — they were jumbled as they traveled through the upper atmosphere and down to Earth.

All together, this information will give scientists a better idea of how these bubbles form and change and how much they disrupt signals — information that could help develop strategies for mitigating these bubbles' disruptive effects.

Damaged satellites

The high-energy, fast-moving particles that fill space are called radiation. Every single spacecraft — from scientific satellites sprinkled throughout the solar system to the communications satellites responsible for relaying the GPS signals we use every day — must weather the harsh radiation of space.

Strikes from tiny, charged particles can spark memory damage or computer upsets on spacecraft, and over time, degrade hardware. The effects are wide-ranging, but ultimately, radiation can impact important scientific data, or prevent people from getting the proper navigation signals they need.

Space Environment Testbeds — or SET, for short — is our mission to study how to better protect satellites from space radiation.

SET aims its sights on a particular neighborhood of near-Earth space called the slot region: the gap between two of Earth’s vast, doughnut-shaped radiation belts, also known as the Van Allen Belts. The slot region is thought to be calmer than the belts, but known to vary during extreme space weather storms driven by the Sun. How much it changes exactly, and how quickly, remains uncertain.

The slot region is an attractive one for satellites — especially commercial navigation and communications satellites that we use every day — because from about 12,000 miles up, it offers not only a relatively friendly radiation environment, but also a wide view of Earth. During intense magnetic storms, however, energetic particles from the outer belt can surge into the slot region. 

SET will survey the slot region, providing some of the first day-to-day weather measurements of this particular neighborhood in near-Earth space. The mission also studies the fine details of how radiation damages instruments and tests different methods to protect them, helping engineers build parts better suited for spaceflight. Ultimately, SET will help other missions improve their design, engineering and operations to avoid future problems, keeping our space technology running smoothly as possible.

For more on our space weather research, follow @NASASun on Twitter and NASA Sun Science on Facebook.

Meet the other NASA missions launching on the Department of Defense's STP-2 mission and get the latest updates at nasa.gov/spacex.

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Space Telescope Gets to Work

Our latest space telescope, Transiting Exoplanet Survey Satellite (TESS), launched in April. This week, planet hunters worldwide received all the data from the first two months of its planet search. This view, from four cameras on TESS, shows just one region of Earth’s southern sky.

The Transiting Exoplanet Survey Satellite (TESS) captured this strip of stars and galaxies in the southern sky during one 30-minute period in August. Created by combining the view from all four of its cameras, TESS images will be used to discover new exoplanets. Notable features in this swath include the Large and Small Magellanic Clouds and a globular cluster called NGC 104. The brightest stars, Beta Gruis and R Doradus, saturated an entire column of camera detector pixels on the satellite’s second and fourth cameras.

Credit: NASA/MIT/TESS

The data in the images from TESS will soon lead to discoveries of planets beyond our solar system – exoplanets. (We’re at 3,848 so far!)

But first, all that data (about 27 gigabytes a day) needs to be processed. And where do space telescopes like TESS get their data cleaned up? At the Star Wash, of course!

TESS sends about 10 billion pixels of data to Earth at a time. A supercomputer at NASA Ames in Silicon Valley processes the raw data, turning those pixels into measures of a star’s brightness.

And that brightness? THAT’S HOW WE FIND PLANETS! A dip in a star’s brightness can reveal an orbiting exoplanet in transit.

TESS will spend a year studying our southern sky, then will turn and survey our northern sky for another year. Eventually, the space telescope will observe 85 percent of Earth’s sky, including 200,000 of the brightest and closest stars to Earth.

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Dark Matter 101: Looking for the missing mass

Here’s the deal — here at NASA we share all kinds of amazing images of planets, stars, galaxies, astronauts, other humans, and such, but those photos can only capture part of what’s out there. Every image only shows ordinary matter (scientists sometimes call it baryonic matter), which is stuff made from protons, neutrons and electrons. The problem astronomers have is that most of the matter in the universe is not ordinary matter – it’s a mysterious substance called dark matter.  

What is dark matter? We don’t really know. That’s not to say we don’t know anything about it – we can see its effects on ordinary matter. We’ve been getting clues about what it is and what it is not for decades. However, it’s hard to pinpoint its exact nature when it doesn’t emit light our telescopes can see. 

Misbehaving galaxies

The first hint that we might be missing something came in the 1930s when astronomers noticed that the visible matter in some clusters of galaxies wasn’t enough to hold the cluster together. The galaxies were moving so fast that they should have gone zinging out of the cluster before too long (astronomically speaking), leaving no cluster behind.

Simulation credit: ESO/L. Calçada

It turns out, there’s a similar problem with individual galaxies. In the 1960s and 70s, astronomers mapped out how fast the stars in a galaxy were moving relative to its center. The outer parts of every single spiral galaxy the scientists looked at were traveling so fast that they should have been flying apart.

Something was missing – a lot of it! In order to explain how galaxies moved in clusters and stars moved in individual galaxies, they needed more matter than scientists could see. And not just a little more matter. A lot . . . a lot, a lot. Astronomers call this missing mass “dark matter” — “dark” because we don’t know what it is. There would need to be five times as much dark matter as ordinary matter to solve the problem.  

Holding things together

Dark matter keeps galaxies and galaxy clusters from coming apart at the seams, which means dark matter experiences gravity the same way we do.

In addition to holding things together, it distorts space like any other mass. Sometimes we see distant galaxies whose light has been bent around massive objects on its way to us. This makes the galaxies appear stretched out or contorted. These distortions provide another measurement of dark matter.

Undiscovered particles?

There have been a number of theories over the past several decades about what dark matter could be; for example, could dark matter be black holes and neutron stars – dead stars that aren’t shining anymore? However, most of the theories have been disproven. Currently, a leading class of candidates involves an as-yet-undiscovered type of elementary particle called WIMPs, or Weakly Interacting Massive Particles.

Theorists have envisioned a range of WIMP types and what happens when they collide with each other. Two possibilities are that the WIMPS could mutually annihilate, or they could produce an intermediate, quickly decaying particle. In both cases, the collision would end with the production of gamma rays — the most energetic form of light — within the detection range of our Fermi Gamma-ray Space Telescope.

Tantalizing evidence close to home

A few years ago, researchers took a look at Fermi data from near the center of our galaxy and subtracted out the gamma rays produced by known sources. There was a left-over gamma-ray signal, which could be consistent with some forms of dark matter.

While it was an exciting finding, the case is not yet closed because lots of things at the center of the galaxy make gamma rays. It’s going to take multiple sightings using other experiments and looking at other astronomical objects to know for sure if this excess is from dark matter.

In the meantime, Fermi will continue the search, as it has over its 10 years in space. Learn more about Fermi and how we’ve been celebrating its first decade in space.

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Gobble Up These Black (Hole) Friday Deals!

Welcome to our 6th annual annual Black Hole Friday! Check out these black hole deals from the past year as you prepare to head out for a shopping spree or hunker down at home to avoid the crowds.

First things first, black holes have one basic rule: They are so incredibly dense that to escape their surface you’d have to travel faster than light. But light speed is the cosmic speed limit . . . so nothing can escape a black hole’s surface!

Black hole birth announcements

Some black holes form when a very large star dies in a supernova explosion and collapses into a superdense object. This is even more jam-packed than the crowds at your local mall — imagine an object 10 times more massive than the Sun squeezed into a sphere with the diameter of New York City!

Some of these collapsing stars also signal their destruction with a huge burst of gamma rays. Our Fermi Gamma-ray Space Telescope and Neil Gehrels Swift Observatory continuously seek out the signals of these gamma ray bursts — black hole birth announcements that come to us from across the universe.

NICER black holes

There are loads of stellar mass black holes, which are just a few 10s of times the Sun’s mass, in our home galaxy alone — maybe even hundreds of millions of them! Our Neutron Star Interior Composition Explorer, or NICER for short, experiment on the International Space Station has been studying some of those relatively nearby black holes.

Near one black hole called GRS 1915+105, NICER found disk winds — fast streams of gas created by heat or pressure. Scientists are still figuring out some puzzles about these types of wind. Where do they come from, for example? And do they change the way material falls into the black hole? Every new example of these disk winds helps astronomers get closer to answering those questions.

Merging monster black holes

But stellar mass black holes aren’t the only ones out there. At the center of nearly every large galaxy lies a supermassive black hole — one with the mass of millions or billions of Suns smooshed into a region no bigger than our solar system.

There’s still some debate about how these monsters form, but astronomers agree that they certainly can collide and combine when their host galaxies collide and combine. Those black holes will have a lot of gas and dust around them. As that material is pulled into the black hole it will heat up due to friction and other forces, causing it to emit light.  A group of scientists wondered what light it would produce and created this mesmerizing visualization showing that most of the light produced around these two black holes is UV or X-ray light. We can’t see those wavelengths with our own eyes, but many telescopes can. Models like this could help scientists know what to look for to spot a merger.

Black holes power bright gamma ray lights

It also turns out that these supermassive black holes are the source of some of the brightest objects in the gamma ray sky! In a type of galaxy called active galactic nuclei (also called “AGN” for short) the central black hole is surrounded by a disk of gas and dust that’s constantly falling into the black hole.

But not only that, some of those AGN have jets of energetic particles that are shooting out from near the black hole at nearly the speed of light! Scientists are studying these jets to try to understand how black holes — which pull everything in with their huge amounts of gravity — provide the energy needed to propel the particles in these jets. If that jet is pointed directly at us, it can appear super-bright in gamma rays and we call it a blazar. These blazars make up more than half of the sources our Fermi space telescope sees.

Catching particles from near a black hole

Sometimes scientists get a two-for-one kind of deal when they’re looking for black holes. Our colleagues at the IceCube Neutrino Observatory actually caught a particle from a blazar 4 billion light-years away. IceCube lies a mile under the ice in Antarctica and uses the ice itself to detect neutrinos, tiny speedy particles that weigh almost nothing and rarely interact with anything. When IceCube caught a super-high-energy neutrino and traced its origin to a specific area of the sky, they turned to the astronomical community to pinpoint the source.

Our Fermi spacecraft scans the entire sky about every three hours and for months it had observed a blazar producing more gamma rays than usual. Flaring is a common characteristic in blazars, so this didn’t attract special attention. But when the alert from IceCube came through, scientists realized the neutrino and the gamma rays came from the same patch of sky! This method of using two or more kinds of signals to learn about one event or object is called multimessenger astronomy, and it’s helping us learn a lot about the universe.

Get more fun facts and information about black holes HERE and follow us on social media today for other cool facts and findings about black holes!

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Blowing Bubbles in the Gamma-ray Sky

Did you know our Milky Way galaxy is blowing bubbles? Two of them, each 25,000 light-years tall! They extend above and below the disk of the galaxy, like the two halves of an hourglass. We can’t see them with our own eyes because they’re only apparent in gamma-ray light, the highest-energy light in the universe.

We didn’t even know these humongous structures were smack in the middle of our galaxy until 2010. Scientists found them when they analyzed the first two years of data from NASA’s Fermi Gamma-ray Space Telescope. They dubbed them the “Fermi bubbles” and found that in addition to being really big and spread out, they seem to have well-defined edges. The bubbles’ shape and the light they give off led scientists to think they were created by a rapid release of energy. But by what? And when?

One possible explanation is that they could be leftovers from the last big meal eaten by the supermassive black hole at the center of our galaxy. This monster is more than 4 million times the mass of our own Sun. Scientists think it may have slurped up a big cloud of hydrogen between 6 and 9 million years ago and then burped jets of hot gas that we see in gamma rays and X-rays.

Another possible explanation is that the bubbles could be the remains of star formation. There are massive clusters of stars at very the center of the Milky Way — sometimes the stars are so closely packed they’re a million times more dense than in the outer suburb of the galaxy where we live. If there was a burst of star formation in this area a few million years ago, it could have created the surge of gas needed to in turn create the Fermi bubbles.

It took us until 2010 to see these Fermi bubbles because the sky is filled with a fog of other gamma rays that can obscure our view. This fog is created when particles moving near light speed bump into gas, dust, and light in the Milky Way. These collisions produce gamma rays, and scientists had to factor out the fog to unveil the bubbles.

Scientists continue to study the possible causes of these massive bubbles using the 10 years of data Fermi has collected so far. Fermi has also made many other exciting discoveries — like the the collision of superdense neutron stars and the nature of space-time. Learn more about Fermi and how we’ve been celebrating its first decade in space.

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