Space Weather - Blog Posts

Farewell to the Van Allen Probes

After seven years of studying the radiation around Earth, the Van Allen Probes spacecraft have retired.

Originally slated for a two-year mission, these two spacecraft studied Earth's radiation belts — giant, donut-shaped clouds of particles surrounding Earth — for nearly seven years. The mission team used the last of their propellant this year to place the spacecraft into a lower orbit that will eventually decay, allowing the Van Allen Probes to re-enter and burn up in Earth's atmosphere.

Earth's radiation belts exist because energized charged particles from the Sun and other sources in space become trapped in our planet's huge magnetic field, creating vast regions around Earth that teem with radiation. This is one of the harshest environments in space — and the Van Allen Probes survived more than three times longer than planned orbiting through this intense region.

The shape, size and intensity of the radiation belts change, meaning that satellites — like those used for telecommunications and GPS — can be bombarded with a sudden influx of radiation. The Van Allen Probes shed new light on what invisible forces drive these changes — like waves of charged particles and electromagnetic fields driven by the Sun, called space weather. 

Here are a few scientific highlights from the Van Allen Probes — from the early days of the mission to earlier this year:

The Van Allen belts were first discovered in 1958, and for decades, scientists thought there were only two concentric belts. But, days after the Van Allen Probes launched, scientists discovered that during times of intense solar activity, a third belt can form.

The belts are composed of charged particles and electromagnetic fields and can be energized by different types of plasma waves. One type, called electrostatic double layers, appear as short blips of enhanced electric field. During one observing period, Probe B saw 7,000 such blips repeatedly pass over the spacecraft in a single minute!

During big space weather storms, which are ultimately caused by activity on the Sun, ions — electrically charged atoms or molecules — can be pushed deep into Earth’s magnetosphere. These particles carry electromagnetic currents that circle around the planet and can dramatically distort Earth’s magnetic field.

Across space, fluctuating electric and magnetic fields can create what are known as plasma waves. These waves intensify during space weather storms and can accelerate particles to incredible speeds. The Van Allen Probes found that one type of plasma wave known as hiss can contribute greatly to the loss of electrons from the belts.

The Van Allen belts are composed of electrons and ions with a range of energies. In 2015, research from the Van Allen Probes found that, unlike the outer belt, there were no electrons with energies greater than a million electron volts in the inner belt.

Plasma waves known as whistler chorus waves are also common in our near-Earth environment. These waves can travel parallel or at an angle to the local magnetic field. The Van Allen Probes demonstrated the two types of waves cannot be present simultaneously, resulting in greater radiation belt particle scattering in certain areas.

Very low frequency chorus waves, another variety of plasma waves, can pump up the energy of electrons to millions of electronvolts. During storm conditions, the Van Allen Probes found these waves can hugely increase the energy of particles in the belts in just a few hours.  

Scientists often use computer simulation models to understand the physics behind certain phenomena. A model simulating particles in the Van Allen belts helped scientists understand how particles can be lost, replenished and trapped by Earth’s magnetic field.

The Van Allen Probes observed several cases of extremely energetic ions speeding toward Earth. Research found that these ions’ acceleration was connected to their electric charge and not to their mass.

The Sun emits faster and slower gusts of charged particles called the solar wind. Since the Sun rotates, these gusts — the fast wind — reach Earth periodically. Changes in these gusts cause the extent of the region of cold ionized gas around Earth — the plasmasphere — to shrink. Data from the Van Allen Probes showed that such changes in the plasmasphere fluctuated at the same rate as the solar rotation — every 27 days.

Though the mission has ended, scientists will use data from the Van Allen Probes for years to come. See the latest Van Allen Probes science at nasa.gov/vanallen.

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Top 5 Technologies Needed for a Spacecraft to Survive Deep Space

When a spacecraft built for humans ventures into deep space, it requires an array of features to keep it and a crew inside safe. Both distance and duration demand that spacecraft must have systems that can reliably operate far from home, be capable of keeping astronauts alive in case of emergencies and still be light enough that a rocket can launch it.

Missions near the Moon will start when the Orion spacecraft leaves Earth atop the world’s most powerful rocket, the Space Launch System. After launch from Kennedy Space Center in Florida, Orion will travel beyond the Moon to a distance more than 1,000 times farther than where the International Space Station flies in low-Earth orbit, and farther than any spacecraft built for humans has ever ventured. To accomplish this feat, Orion has built-in technologies that enable the crew and spacecraft to explore far into the solar system. Let’s check out the top five: 

Systems to Live and Breathe

As humans travel farther from Earth for longer missions, the systems that keep them alive must be highly reliable while taking up minimal mass and volume. Orion will be equipped with advanced environmental control and life support systems designed for the demands of a deep space mission. A high-tech system already being tested aboard the space station will remove carbon dioxide (CO2) and humidity from inside Orion. The efficient system replaces many chemical canisters that would consume up to 10 percent of crew livable area. To save additional space, Orion will also have a new compact toilet, smaller than the one on the space station.

Highly reliable systems are critically important when distant crew will not have the benefit of frequent resupply shipments to bring spare parts from Earth. Even small systems have to function reliably to support life in space, from a working toilet to an automated fire suppression system or exercise equipment that helps astronauts stay in shape to counteract the zero-gravity environment. Distance from home also demands that Orion have spacesuits capable of keeping astronaut alive for six days in the event of cabin depressurization to support a long trip home.

Proper Propulsion

The farther into space a vehicle ventures, the more capable its propulsion systems need to be in order to maintain its course on the journey with precision and ensure its crew can get home.

Orion’s highly capable service module serves as the powerhouse for the spacecraft and provides propulsion capabilities that enable it to go around the Moon and back on exploration missions. The service module has 33 engines of various sizes. The main engine will provide major in-space maneuvering capabilities throughout the mission such as inserting Orion into lunar orbit and firing powerfully enough to exit orbit for a return trip to Earth. The other 32 engines are used to steer and control Orion on orbit.

In part due to its propulsion capabilities, including tanks that can hold nearly 2,000 gallons of propellant and a back up for the main engine in the event of a failure, Orion’s service module is equipped to handle the rigors of travel for missions that are both far and long. It has the ability to bring the crew home in a variety of emergency situations.

The Ability to Hold Off the Heat

Going to the Moon is no easy task, and it’s only half the journey. The farther a spacecraft travels in space, the more heat it will generate as it returns to Earth. Getting back safely requires technologies that can help a spacecraft endure speeds 30 times the speed of sound and heat twice as hot as molten lava or half as hot as the sun.

When Orion returns from the Moon it will be traveling nearly 25,000 mph, a speed that could cover the distance from Los Angeles to New York City in six minutes. Its advanced heat shield, made with a material called AVCOAT, is designed to wear away as it heats up. Orion’s heat shield is the largest of its kind ever built and will help the spacecraft withstand temperatures around 5,000 degrees Fahrenheit during reentry though Earth’s atmosphere.

Before reentry, Orion also will endure a 700-degree temperature range from about minus 150 to 550 degrees Fahrenheit. Orion’s highly capable thermal protection system, paired with thermal controls, will protect it during periods of direct sunlight and pitch black darkness while its crews comfortably enjoy a safe and stable interior temperature of about 77 degrees Fahrenheit.

Radiation Protection

As a spacecraft travels on missions beyond the protection of Earth’s magnetic field, it will be exposed to a harsher radiation environment than in low-Earth orbit with greater amounts of radiation from charged particles and solar storms. This kind of radiation can cause disruptions to critical computers, avionics and other equipment. Humans exposed to large amounts of radiation can experience both acute and chronic health problems ranging from near-term radiation sickness to the potential of developing cancer in the long-term.

Orion was designed from the start with built in system-level features to ensure reliability of essential elements of the spacecraft during potential radiation events. For example, Orion is equipped with four identical computers that each are self-checking, plus an entirely different backup computer, to ensure it can still send commands in the event of a disruption. Engineers have tested parts and systems to a high standard to ensure that all critical systems remain operable even under extreme circumstances.

Orion also has a makeshift storm shelter below the main deck of the crew module. In the event of a solar radiation event, we developed plans for crew on board to create a temporary shelter inside using materials on board. A variety of radiation sensors will also be on the spacecraft to help scientists better understand the radiation environment far away from Earth. One investigation, called AstroRad, will fly on Exploration Mission-1 and test an experimental vest that has the potential to help shield vital organs and decrease exposure from solar particle events.

Constant Communication and Navigation

Spacecraft venturing far from home go beyond the Global Positioning System (GPS) in space and above communication satellites in Earth orbit. To talk with mission control in Houston, Orion’s communication and navigation systems will switch from our Tracking and Data Relay Satellites (TDRS) system used by the International Space Station, and communicate through the Deep Space Network.

Orion is equipped with backup communication and navigation systems to help the spacecraft stay in contact with the ground and orient itself if its primary systems fail. The backup navigation system, a relatively new technology called optical navigation, uses a camera to take pictures of the Earth, Moon and stars and autonomously triangulate Orion’s position from the photos. Its backup emergency communications system doesn’t use the primary system or antennae for high-rate data transfer.

Keep up with all the latest news on our newest, state-of-the art spacecraft by following NASA Orion on Facebook and Twitter. 

More on our Moon to Mars plans, here. 

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We’re Turning up the Heat on the Artemis I Spacecraft 🔥

The Orion spacecraft for Artemis I is headed to Ohio, where a team of engineers and technicians at our Plum Brook Station stand ready to test it under extreme simulated in-space conditions, like temperatures up to 300°F, at the world’s premier space environments test facility.

Why so much heat? What’s the point of the test? We’ve got answers to all your burning questions.

Here, in the midst of a quiet, rural landscape in Sandusky, Ohio, is our Space Environments Complex, home of the world’s most powerful space simulation facilities. The complex houses a massive thermal vacuum chamber (100-foot diameter and 122-foot tall), which allows us to “test like we fly” and accurately simulate space flight conditions while still on the ground.

Orion’s upcoming tests here are important because they will confirm the spacecraft’s systems perform as designed, while ensuring safe operation for the crew during future Artemis missions.

Tests will be completed in two phases, beginning with a thermal vacuum test, lasting approximately 60 days, inside the vacuum chamber to stress-test and check spacecraft systems while powered on.

During this phase, the spacecraft will be subjected to extreme temperatures, ranging from -250°F to 300 °F, to replicate flying in-and-out of sunlight and shadow in space.

To simulate the extreme temperatures of space, a specially-designed system, called the Heat Flux, will surround Orion like a cage and heat specific parts of the spacecraft during the test. This image shows the Heat Flux installed inside the vacuum chamber. The spacecraft will also be surrounded on all sides by a cryogenic-shroud, which provides the cold background temperatures of space.

We’ll also perform electromagnetic interference tests. Sounds complicated, but, think of it this way. Every electronic component gives off some type of electromagnetic field, which can affect the performance of other electronics nearby—this is why you’re asked to turn off your cellphone on an airplane. This testing will ensure the spacecraft’s electronics work properly when operated at the same time and won’t be affected by outside sources.

What’s next? After the testing, we’ll send Orion back to our Kennedy Space Center in Florida, where it will be installed atop the powerful Space Launch System rocket in preparation for their first integrated test flight, called Artemis I, which is targeted for 2020.

To learn more about the Artemis program, why we’re going to the Moon and our progress to send the first woman and the next man to the lunar surface by 2024, visit: nasa.gov/moon2mars.

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Our Newest Solar Scope Is Ready for a Balloon Ride 🎈

Along with the Korea Astronomy and Space Science Institute, or KASI, we're getting ready to test a new way to see the Sun, high over the New Mexico desert.

A balloon — which looks a translucent white pumpkin, but large enough to hug a football field — will soon take flight, carrying a solar scope called BITSE. BITSE is a coronagraph, a special kind of telescope that blocks the bright face of the Sun to reveal its dimmer atmosphere, called the corona. BITSE stands for Balloon-borne Investigation of Temperature and Speed of Electrons in the corona.

Its goal? Explaining how the Sun spits out the solar wind, the stream of charged particles that blows constantly from the Sun. Scientists generally know it forms in the corona, but exactly how it does so is a mystery.

The solar wind is important because it’s the stuff that fills the space around Earth and all the other planets in our solar system. And, understanding how the solar wind works is key to predicting how solar eruptions travel. It’s a bit like a water slide: The way it flows determines how solar storms barrel through space. Sometimes, those storms crash into our planet’s magnetic field, sparking disturbances that can interfere with satellites and communications signals we use every day, like radio or GPS.

Right now, scientists and engineers are in Fort Sumner, New Mexico, preparing to fly BITSE up to the edge of the atmosphere. BITSE will take pictures of the corona, measuring the density, temperature and speed of negatively charged particles — called electrons — in the solar wind. Scientists need these three things to answer the question of how the solar wind forms.

One day, scientists hope to send an instrument like BITSE to space, where it can study the Sun day in and day out, and help us understand the powerful forces that push the solar wind out to speeds of 1 million miles per hour. BITSE’s balloon flight is an important step towards space, since it will help this team of scientists and engineers fine-tune their tech for future space-bound missions.  

Hours before sunrise, technicians from our Columbia Scientific Balloon Facility’s field site in Fort Sumner will ready the balloon for flight, partially filling the large plastic envelope with helium. The balloon is made of polyethylene — the same stuff grocery bags are made of — and is about as thick as a plastic sandwich bag, but much stronger. As the balloon rises higher into the sky, the gas in the balloon expands and the balloon grows to full size.

BITSE will float 22 miles over the desert. For at least six hours, it will drift, taking pictures of the Sun’s seething hot atmosphere. By the end of the day, it will have collected 40 feature-length movies’ worth of data.

BITSE’s journey to the sky began with an eclipse. Coronagraphs use a metal disk to mimic a total solar eclipse — but instead of the Moon sliding in between the Sun and Earth, the disk blocks the Sun’s face to reveal the dim corona. During the Aug. 21, 2017, total eclipse, our scientists tested key parts of this instrument in Madras, Oregon.

Now, the scientists are stepping out from the Moon’s shadow. A balloon will take BITSE up to the edge of the atmosphere. Balloons are a low-cost way to explore this part of the sky, allowing scientists to make better measurements and perform tests they can’t from the ground.

BITSE carries several important technologies. It’s built on one stage of lens, rather than three, like traditional coronagraphs. That means it’s designed more simply, and less likely to have a mechanical problem. And, it has a couple different sets of specialized filters that capture different kinds of light: polarized light — light waves that bob in certain directions — and specific wavelengths of light. The combination of these images provides scientists with information on the density, temperature and speed of electrons in the corona.

More than 22 miles over the ground, BITSE will fly high above birds, airplanes, weather and the blue sky itself. As the atmosphere thins out, there are less air particles to scatter light. That means at BITSE’s altitude, the sky is dimmer. These are good conditions for a coronagraph, whose goal is taking images of the dim corona. But even the upper atmosphere is brighter than space.

That’s why scientists are so eager to test BITSE on this balloon, and develop their instrument for a future space mission. The solar scope is designed to train its eyes on a slice of the corona that’s not well-studied, and key to solar wind formation. One day, a version of BITSE could do this from space, helping scientists gather new clues to the origins of the solar wind.  

At the end of BITSE’s flight, the crew at the Fort Sumner field site will send termination commands, kicking off a sequence that separates the instrument and balloon, deploys the instrument’s parachute, and punctures the balloon. An airplane circling overhead will keep watch over the balloon’s final moments, and relay BITSE’s location. At the end of its flight, far from where it started, the coronagraph will parachute to the ground. A crew will drive into the desert to recover both the balloon and BITSE at the end of the day.

For more information on how we use balloons for high-altitude science missions, visit: https://www.nasa.gov/scientificballoons

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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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A Tour of Storms Across the Solar System

Earth is a dynamic and stormy planet with everything from brief, rumbling thunderstorms to enormous, raging hurricanes, which are some of the most powerful and destructive storms on our world. But other planets also have storm clouds, lightning — even rain, of sorts. Let’s take a tour of some of the unusual storms in our solar system and beyond.

Tune in May 22 at 3 p.m. for more solar system forecasting with NASA Chief Scientist Jim Green during the latest installment of NASA Science Live: https://www.nasa.gov/nasasciencelive.

1. At Mercury: A Chance of Morning Micrometeoroid Showers and Magnetic ‘Tornadoes’

Mercury, the planet nearest the Sun, is scorching hot, with daytime temperatures of more than 800 degrees Fahrenheit (about 450 degrees Celsius). It also has weak gravity — only about 38% of Earth's — making it hard for Mercury to hold on to an atmosphere.

Its barely there atmosphere means Mercury doesn’t have dramatic storms, but it does have a strange "weather" pattern of sorts: it’s blasted with micrometeoroids, or tiny dust particles, usually in the morning. It also has magnetic “tornadoes” — twisted bundles of magnetic fields that connect the planet’s magnetic field to space.

2. At Venus: Earth’s ‘Almost’ Twin is a Hot Mess

Venus is often called Earth's twin because the two planets are similar in size and structure. But Venus is the hottest planet in our solar system, roasting at more than 800 degrees Fahrenheit (430 degrees Celsius) under a suffocating blanket of sulfuric acid clouds and a crushing atmosphere. Add to that the fact that Venus has lightning, maybe even more than Earth. 

In visible light, Venus appears bright yellowish-white because of its clouds. Earlier this year, Japanese researchers found a giant streak-like structure in the clouds based on observations by the Akatsuki spacecraft orbiting Venus.

3. At Earth: Multiple Storm Hazards Likely

Earth has lots of storms, including thunderstorms, blizzards and tornadoes. Tornadoes can pack winds over 300 miles per hour (480 kilometers per hour) and can cause intense localized damage.

But no storms match hurricanes in size and scale of devastation. Hurricanes, also called typhoons or cyclones, can last for days and have strong winds extending outward for 675 miles (1,100 kilometers). They can annihilate coastal areas and cause damage far inland.

4. At Mars: Hazy with a Chance of Dust Storms

Mars is infamous for intense dust storms, including some that grow to encircle the planet. In 2018, a global dust storm blanketed NASA's record-setting Opportunity rover, ending the mission after 15 years on the surface.

Mars has a thin atmosphere of mostly carbon dioxide. To the human eye, the sky would appear hazy and reddish or butterscotch colored because of all the dust suspended in the air. 

5. At Jupiter: A Shrinking Icon

It’s one of the best-known storms in the solar system: Jupiter’s Great Red Spot. It’s raged for at least 300 years and was once big enough to swallow Earth with room to spare. But it’s been shrinking for a century and a half. Nobody knows for sure, but it's possible the Great Red Spot could eventually disappear.

6. At Saturn: A Storm Chasers Paradise

Saturn has one of the most extraordinary atmospheric features in the solar system: a hexagon-shaped cloud pattern at its north pole. The hexagon is a six-sided jet stream with 200-mile-per-hour winds (about 322 kilometers per hour). Each side is a bit wider than Earth and multiple Earths could fit inside. In the middle of the hexagon is what looks like a cosmic belly button, but it’s actually a huge vortex that looks like a hurricane.

Storm chasers would have a field day on Saturn. Part of the southern hemisphere was dubbed "Storm Alley" by scientists on NASA's Cassini mission because of the frequent storm activity the spacecraft observed there. 

7. At Titan: Methane Rain and Dust Storms

Earth isn’t the only world in our solar system with bodies of liquid on its surface. Saturn’s moon Titan has rivers, lakes and large seas. It’s the only other world with a cycle of liquids like Earth’s water cycle, with rain falling from clouds, flowing across the surface, filling lakes and seas and evaporating back into the sky. But on Titan, the rain, rivers and seas are made of methane instead of water.

Data from the Cassini spacecraft also revealed what appear to be giant dust storms in Titan’s equatorial regions, making Titan the third solar system body, in addition to Earth and Mars, where dust storms have been observed.

8. At Uranus: A Polar Storm

Scientists were trying to solve a puzzle about clouds on the ice giant planet: What were they made of? When Voyager 2 flew by in 1986, it spotted few clouds. (This was due in part to the thick haze that envelops the planet, as well as Voyager's cameras not being designed to peer through the haze in infrared light.) But in 2018, NASA’s Hubble Space Telescope snapped an image showing a vast, bright, stormy cloud cap across the north pole of Uranus.

9. At Neptune: Methane Clouds

Neptune is our solar system's windiest world. Winds whip clouds of frozen methane across the ice giant planet at speeds of more than 1,200 miles per hour (2,000 kilometers per hour) — about nine times faster than winds on Earth.

Neptune also has huge storm systems. In 1989, NASA’s Voyager 2 spotted two giant storms on Neptune as the spacecraft zipped by the planet. Scientists named the storms “The Great Dark Spot” and “Dark Spot 2.”

10. It’s Not Just Us: Extreme Weather in Another Solar System

Scientists using NASA’s Hubble Space Telescope made a global map of the glow from a turbulent planet outside our solar system. The observations show the exoplanet, called WASP-43b, is a world of extremes. It has winds that howl at the speed of sound, from a 3,000-degree-Fahrenheit (1,600-degree-Celsius) day side, to a pitch-black night side where temperatures plunge below 1,000 degrees Fahrenheit (500 degrees Celsius).

Discovered in 2011, WASP-43b is located 260 light-years away. The planet is too distant to be photographed, but astronomers detected it by observing dips in the light of its parent star as the planet passes in front of it.

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Spilling the Sun’s Secrets

You might think you know the Sun: It looks quiet and unchanging. But the Sun has secrets that scientists have been trying to figure out for decades.  

One of our new missions — Parker Solar Probe — is aiming to spill the Sun’s secrets and shed new light on our neighbor in the sky.

Even though it’s 93 million miles away, the Sun is our nearest and best laboratory for understanding the inner workings of stars everywhere. We’ve been spying on the Sun with a fleet of satellites for decades, but we’ve never gotten a close-up of our nearest star.

This summer, Parker Solar Probe is launching into an orbit that will take it far closer to the Sun than any instrument has ever gone. It will fly close enough to touch the Sun, sweeping through the outer atmosphere — the corona — 4 million miles above the surface.

This unique viewpoint will do a lot more than provide gossip on the Sun. Scientists will take measurements to help us understand the Sun’s secrets — including those that can affect Earth.

Parker Solar Probe is equipped with four suites of instruments that will take detailed measurements from within the Sun's corona, all protected by a special heat shield to keep them safe and cool in the Sun's ferocious heat.

The corona itself is home to one of the Sun’s biggest secrets: The corona's mysteriously high temperatures. The corona, a region of the Sun’s outer atmosphere, is hundreds of times hotter than the surface below. That's counterintuitive, like if you got warmer the farther you walked from a campfire, but scientists don’t yet know why that's the case.

Some think the excess heat is delivered by electromagnetic waves called Alfvén waves moving outwards from the Sun’s surface. Others think it might be due to nanoflares — bomb-like explosions that occur on the Sun’s surface, similar to the flares we can see with telescopes from Earth, but smaller and much more frequent. Either way, Parker Solar Probe's measurements direct from this region itself should help us pin down what's really going on.

We also want to find out what exactly accelerates the solar wind — the Sun's constant outpouring of material that rushes out at a million miles per hour and fills the Solar System far past the orbit of Pluto. The solar wind can cause space weather when it reaches Earth — triggering things like the aurora, satellite problems, and even, in rare cases, power outages.

We know where the solar wind comes from, and that it gains its speed somewhere in the corona, but the exact mechanism of that acceleration is a mystery. By sampling particles directly at the scene of the crime, scientists hope Parker Solar Probe can help crack this case.

Parker Solar Probe should also help us uncover the secrets of some of the fastest particles from the Sun. Solar energetic particles can reach speeds of more than 50% the speed of light, and they can interfere with satellites with little warning because of how fast they move. We don't know how they get so fast — but it's another mystery that should be solved with Parker Solar Probe on the case.  

Parker Solar Probe launches summer 2018 on a seven-year mission to touch the Sun. Keep up with the latest on the Sun at @NASASun on Twitter, and follow along with Parker Solar Probe's last steps to launch at nasa.gov/solarprobe.

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Our Sun is More than Meets the Eye

The Sun may look unchanging to us here on Earth, but that’s not the whole story.

In visible light – the light our eyes can see – the Sun looks like an almost featureless orange disk, peppered with the occasional sunspot. (Important note: Never look at the Sun directly, and always use a proper filter for solar viewing – or tune in to our near-real time satellite feeds!)

But in other kinds of light, it’s a different picture. The Sun emits light across the electromagnetic spectrum, including the relatively narrow range of light we can see, as well as wavelengths that are invisible to our eyes. Different wavelengths convey information about different components of the Sun’s surface and atmosphere, so watching the Sun in multiple types of light helps us paint a fuller picture.

Watching the Sun in these wavelengths reveals how active it truly is. This image, captured in a wavelength of extreme ultraviolet light at 131 Angstroms, shows a solar flare. Solar flares are intense bursts of light radiation caused by magnetic events on the Sun, and often associated with sunspots. The light radiation from solar flares can disturb part of Earth’s atmosphere where radio signals travel, causing short-lived problems with communications systems and GPS.

Looking at the Sun in extreme ultraviolet light also reveals structures like coronal loops (magnetic loops traced out by charged particles spinning along magnetic field lines)…

…solar prominence eruptions…

…and coronal holes (magnetically open areas on the Sun from which solar wind rushes out into space).

Though extreme ultraviolet light shows the Sun's true colors, specialized instruments let us see some of the Sun's most significant activity in visible light.

A coronagraph is a camera that uses a solid disk to block out the Sun’s bright face, revealing the much fainter corona, a dynamic part of the Sun’s atmosphere. Coronagraphs also reveal coronal mass ejections, or CMEs, which are explosions of billions of tons of solar material into space. Because this material is magnetized, it can interact with Earth’s magnetic field and trigger space weather effects like the aurora, satellite problems, and even – in extreme cases – power outages.

The Sun is also prone to bursts of energetic particles. These particles are blocked by Earth’s magnetic field and atmosphere, but they could pose a threat to astronauts traveling in deep space, and they can interfere with our satellites. This clip shows an eruption of energetic particles impacting a Sun-observing satellite, creating the 'snow' in the image.

We keep watch on the Sun 24/7 with a fleet of satellites to monitor and better understand this activity. And this summer, we’re going one step closer with the launch of Parker Solar Probe, a mission to touch the Sun. Parker Solar Probe will get far closer to the Sun than any other spacecraft has ever gone – into the corona, within 4 million miles of the surface – and will send back unprecedented direct measurements from the regions thought to drive much of the Sun’s activity. More information about the fundamental processes there can help round out and improve models to predict the space weather that the Sun sends our way.

Keep up with the latest on the Sun at @NASASun on Twitter, and follow along with Parker Solar Probe’s last steps to launch at nasa.gov/solarprobe.

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