Sun Science - Blog Posts

Our Parker Solar Probe Just Touched the Sun!

For the first time in history, a spacecraft has touched the Sun. Our Parker Solar Probe flew right through the Sun’s atmosphere, the corona. (That’s the part of the Sun that we can see during a total solar eclipse.)

This marks one great step for Parker Solar Probe and one giant leap for solar science! Landing on the Moon helped scientists better understand how it was formed. Now, touching the Sun will help scientists understand our star and how it influences worlds across the solar system.

Unlike Earth, the Sun doesn’t have a solid surface (it’s a giant ball of seething, boiling gases). But the Sun does have a superheated atmosphere. Heat and pressure push solar material away from the Sun. Eventually, some of that material escapes the pull of the Sun’s gravity and magnetism and becomes the solar wind, which gusts through the entire solar system.

But where exactly does the Sun’s atmosphere end and the solar wind begin? We’ve never known for sure. Until now!

In April 2021, Parker Solar Probe swooped near the Sun. It passed through a massive plume of solar material in the corona. This was like flying into the eye of a hurricane. That flow of solar stuff — usually a powerful stream of particles — hit the brakes and went into slow-motion.

For the first time, Parker Solar Probe found itself in a place where the Sun’s magnetism and gravity were strong enough to stop solar material from escaping. That told scientists Parker Solar Probe had passed the boundary: On one side, space filled with solar wind, on the other, the Sun’s atmosphere.

Parker Solar Probe’s proximity to the Sun has led to another big discovery: the origin of switchbacks, zig-zag-shaped magnetic kinks in the solar wind.

These bizarre shapes were first observed in the 1990s. Then, in 2019, Parker Solar Probe revealed they were much more common than scientists first realized. But they still had questions, like where the switchbacks come from and how the Sun makes them.

Recently, Parker Solar Probe dug up two important clues. First, switchbacks tend to have lots of helium, which scientists know comes from the solar surface. And they come in patches.

Those patches lined up just right with magnetic funnels that appear on the Sun’s surface. Matching these clues up like puzzle pieces, scientists realized switchbacks must come from near the surface of the Sun.

Figuring out where switchbacks come from and how they form will help scientists understand how the Sun produces the solar wind. And that could clue us into one of the Sun’s biggest mysteries: why the Sun’s atmosphere is much, much hotter than the surface below.

Parker Solar Probe will fly closer and closer to the Sun. Who knows what else we’ll discover?

Make sure to follow us on Tumblr for your regular dose of space!

New Sun Science Stamps from the U.S. Postal Service

To start off the summer, the U.S. Postal Service issued a set of stamps showcasing views of the Sun from our Solar Dynamics Observatory!

Since its launch in 2010, the Solar Dynamics Observatory (or SDO) has kept up a near-constant watch on the Sun from its vantage point in orbit around Earth. SDO watches the Sun in more than 10 different types of light, including some that are absorbed by Earth’s atmosphere so can only be seen from space. These different types of light allow scientists to study different parts of the Sun – from its surface to its atmosphere – and better understand the solar activity that can affect our technology on Earth and in space.

The new set of stamps features 10 images from SDO. Most of these images are in extreme ultraviolet light, which is invisible to human eyes.

Let’s explore the science behind some of the stamps!

Coronal hole (May 2016)

The dark area capping the northern polar region of the Sun is a coronal hole, a magnetically open area on the Sun from which high-speed solar wind escapes into space. Such high-speed solar wind streams can spark magnificent auroral displays on Earth when they collide with our planet’s magnetic field.

Solar flare (August 2011)

The bright flash on the Sun’s upper right is a powerful solar flare. Solar flares are bursts of light and energy that can disturb the part of Earth’s atmosphere where GPS and radio signals travel.

Active Sun (October 2014)

This view highlights the many active regions dotting the Sun’s surface. Active regions are areas of intense and complex magnetic fields on the Sun – linked to sunspots – that are prone to erupting with solar flares or explosions of material called coronal mass ejections.

Plasma blast (August 2012)

These images show a burst of material from the Sun, called a coronal mass ejection. These eruptions of magnetized solar material can create space weather effects on Earth when they collide with our planet’s magnetosphere, or magnetic environment – including aurora, satellite disruptions, and, when extreme, even power outages.

Coronal loops (July 2012)

These images show evolving coronal loops across the limb and disk of the Sun. Just days after these images were taken, the Sun unleashed a powerful solar flare.

Coronal loops are often found over sunspots and active regions, which are areas of intense and complex magnetic fields on the Sun.

Sunspots (October 2014)

This view in visible light – the type of light we can see – shows a cluster of sunspots near the center of the Sun. Sunspots appear dark because they are relatively cool compared to surrounding material, a consequence of the way their extremely dense magnetic field prevents heated material from rising to the solar surface.

For more Sun science, follow NASA Sun on Twitter, on Facebook, or on the web.

Make sure to follow us on Tumblr for your regular dose of space!

June 10 Solar Eclipse in the Northern Hemisphere!

On June 10, people in parts of the northern hemisphere will have the chance to witness a solar eclipse.

Watch the full visualization of the eclipse.

The June 10 eclipse is an annular solar eclipse, meaning that the Sun will never be completely covered by the Moon. The Moon’s orbit around the Earth is not a perfect circle, so throughout each month, the Moon’s distance from Earth varies. During an annular eclipse, the Moon is far enough away from Earth that the Moon appears smaller than the Sun in the sky. Since the Moon does not block the entire view of the Sun, it will look like a dark disk on top of a larger, bright disk. This creates what looks like a ring of fire around the Moon.

People in the narrow path of annularity — which, for this eclipse, cuts through Canada, Greenland, and northern Russia — will see the ring of fire effect as the Moon passes across the Sun.

Credit: Dale Cruikshank

Outside this path of annularity, many people in the northern hemisphere have a chance to see a partial solar eclipse. The partial eclipse will fall on parts of the eastern United States, as well as northern Alaska. Some locations will only see a very small piece of the Sun covered, while locations closer to the path of annularity can see the Moon cover most of the Sun.

To learn which times the eclipse may be visible in certain areas, you can click anywhere on the map here. (Note that the maximum obscuration and maximum eclipse timing noted on this map may occur before sunrise in many locations.)

This solar eclipse is a pair with the total lunar eclipse that happened on May 26.

Both solar and lunar eclipses happen when the Sun, Moon, and Earth line up in the same plane — a lunar eclipse happens when Earth is in the middle and casts its shadow on the Moon, and a solar eclipse happens when the Moon is in the middle and casts its shadow on Earth. The Moon’s orbit is tilted, so it’s usually too high or too low for this alignment to work out.

The May 26 lunar eclipse was a supermoon lunar eclipse, meaning that the full moon happened while the Moon was near its closest point to Earth, making the Moon appear larger in the sky. The solar eclipse happens at the opposite point of the Moon’s orbit, during the new moon — and in this case, the new moon happens near the Moon’s farthest point from Earth, making the Moon appear smaller and resulting in an annular (rather than total) solar eclipse.

How to watch the eclipse

From anywhere: Watch the eclipse online with us! Weather permitting, we’ll be sharing live telescope views of the partial eclipse courtesy of Luc Boulard of the Royal Astronomical Society of Canada Sudbury Centre. Tune in starting at 5 a.m. EDT on June 10 at nasa.gov/live.

From the path of the annular or partial eclipse: Be sure to take safety precuations if you plan to watch in person!

It is never safe to look directly at the Sun's rays, even if the Sun is partly or mostly obscured, like during a partial or annular eclipse — doing so can severely harm your eyes. If you’re planning to watch the eclipse on June 10, you should use solar viewing glasses or an indirect viewing method at all points during the eclipse if you want to face the Sun. Solar viewing glasses, sometimes called eclipse glasses, are NOT regular sunglasses; regular sunglasses are not safe for viewing the Sun.

If you don’t have solar viewing or eclipse glasses, you can use an alternate indirect method like a pinhole projector. Pinhole projectors shouldn’t be used to look at the Sun; instead, they’re an easy way to project an image of the Sun onto a surface. Read more about how to create a pinhole projector.

This is a sunrise eclipse in the contiguous U.S. At locations in the lower 48 states that can see the partial eclipse, the show starts before sunrise, when the Sun is still below the horizon. That means the best chance to see the eclipse in these locations will be during and shortly after sunrise, when the Sun is very low in the sky. In northern Alaska, the eclipse happens in the very early hours of June 10 when the Sun is low on the horizon.

Bottom line: If you’re trying to watch the eclipse in the contiguous U.S., look for a location with a clear view of the horizon to the northeast, and plan to watch starting at sunrise with your solar filter or indirect viewer.

The next two eclipses in the continental U.S. are in 2023 and 2024. The annular solar eclipse of Oct. 14, 2023, will cut from Oregon to Texas, and the total solar eclipse of April 8, 2024, will pass from Texas to Maine. Keep up with the latest on eclipses and eclipse science at nasa.gov/eclipse.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.

25 Years in Space for ESA & NASA’s Sun-Watching SOHO

A quarter-century ago, the Solar and Heliospheric Observatory (SOHO) launched to space. Its 25 years of data have changed the way we think about the Sun — illuminating everything from the Sun’s inner workings to the constant changes in its outermost atmosphere.

SOHO — a joint mission of the European Space Agency and NASA — carries 12 instruments to study different aspects of the Sun. One of the gamechangers was SOHO’s coronagraph, a type of instrument that uses a solid disk to block out the bright face of the Sun and reveal the relatively faint outer atmosphere, the corona. With SOHO’s coronagraph, scientists could image giant eruptions of solar material and magnetic fields, called coronal mass ejections, or CMEs. SOHO’s images revealed shape and structure of CMEs in breathtaking detail.

These solar storms can impact robotic spacecraft in their path, or — when intense and aimed at Earth — threaten astronauts on spacewalks and even disrupt power grids on the ground. SOHO is particularly useful in viewing Earth-bound storms, called halo CMEs — so called because when a CME barrels toward us on Earth, it appears circular, surrounding the Sun, much like watching a balloon inflate by looking down on it.

Before SOHO, the scientific community debated whether or not it was even possible to witness a CME coming straight toward us. Today, SOHO images are the backbone of space weather prediction models, regularly used in forecasting the impacts of space weather events traveling toward Earth.

Beyond the day-to-day monitoring of space weather, SOHO has been able to provide insight about our dynamic Sun on longer timescales as well. With 25 years under its belt, SOHO has observed a full magnetic cycle — when the Sun’s magnetic poles switch places and then flip back again, a process that takes about 22 years in total. This trove of data has led to revolutions in solar science: from revelations about the behavior of the solar core to new insight into space weather events that explode from the Sun and travel throughout the solar system.

Data from SOHO, sonified by the Stanford Experimental Physics Lab, captures the Sun’s natural vibrations and provides scientists with a concrete representation of its dynamic movements.

The legacy of SOHO’s instruments — such as the extreme ultraviolet imager, the first of its kind to fly in orbit — also paved the way for the next generation of NASA solar satellites, like the Solar Dynamics Observatory and STEREO. Even with these newer instruments now in orbit, SOHO’s data remains an invaluable part of solar science, producing nearly 200 scientific papers every year.

Relatively early in its mission, SOHO had a brush with catastrophe. During a routine calibration procedure in June 1998, the operations team lost contact with the spacecraft. With the help of a radio telescope in Arecibo, the team eventually located SOHO and brought it back online by November of that year. But luck only held out so long: Complications from the near loss emerged just weeks later, when all three gyroscopes — which help the spacecraft point in the right direction — failed. The spacecraft was no longer stabilized. Undaunted, the team’s software engineers developed a new program that would stabilize the spacecraft without the gyroscopes. SOHO resumed normal operations in February 1999, becoming the first spacecraft of its kind to function without gyroscopes.

SOHO’s coronagraph have also helped the Sun-studying mission become the greatest comet finder of all time. The mission’s data has revealed more than 4,000 comets to date, many of which were found by citizen scientists. SOHO’s online data during the early days of the mission made it possible for anyone to carefully scrutinize a image and potentially spot a comet heading toward the Sun. Amateur astronomers from across the globe joined the hunt and began sending their findings to the SOHO team. To ease the burden on their inboxes, the team created the SOHO Sungrazer Project, where citizen scientists could share their findings.

Keep up with the latest SOHO findings at nasa.gov/soho, and follow along with @NASASun on Twitter and facebook.com/NASASunScience.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.

Tracking the Sun’s Cycles

Scientists just announced that our Sun is in a new cycle.

Solar activity has been relatively low over the past few years, and now that scientists have confirmed solar minimum was in December 2019, a new solar cycle is underway — meaning that we expect to see solar activity start to ramp up over the next several years.

The Sun goes through natural cycles, in which the star swings from relatively calm to stormy. At its most active — called solar maximum — the Sun is freckled with sunspots, and its magnetic poles reverse. At solar maximum, the Sun’s magnetic field, which drives solar activity, is taut and tangled. During solar minimum, sunspots are few and far between, and the Sun’s magnetic field is ordered and relaxed.

Understanding the Sun’s behavior is an important part of life in our solar system. The Sun's violent outbursts can disturb the satellites and communications signals traveling around Earth, or one day, Artemis astronauts exploring distant worlds. Scientists study the solar cycle so we can better predict solar activity.

Measuring the solar cycle

Surveying sunspots is the most basic of ways we study how solar activity rises and falls over time, and it’s the basis of many efforts to track the solar cycle. Around the world, observers conduct daily sunspot censuses. They draw the Sun at the same time each day, using the same tools for consistency. Together, their observations make up the international sunspot number, a complex task run by the World Data Center for the Sunspot Index and Long-term Solar Observations, at the Royal Observatory of Belgium in Brussels, which tracks sunspots and pinpoints the highs and lows of the solar cycle. Some 80 stations around the world contribute their data.

Credit: USET data/image, Royal Observatory of Belgium, Brussels

Other indicators besides sunspots can signal when the Sun is reaching its low. In previous cycles, scientists have noticed the strength of the Sun’s magnetic field near the poles at solar minimum hints at the intensity of the next maximum. When the poles are weak, the next peak is weak, and vice versa.

Another signal comes from outside the solar system. Cosmic rays are high-energy particle fragments, the rubble from exploded stars in distant galaxies that shoot into our solar system with astounding energy. During solar maximum, the Sun’s strong magnetic field envelops our solar system in a magnetic cocoon that is difficult for cosmic rays to infiltrate. In off-peak years, the number of cosmic rays in the solar system climbs as more and more make it past the quiet Sun. By tracking cosmic rays both in space and on the ground, scientists have yet another measure of the Sun’s cycle.

Since 1989, an international panel of experts—sponsored by NASA and NOAA—meets each decade to make their prediction for the next solar cycle. The prediction includes the sunspot number, a measure of how strong a cycle will be, and the cycle’s expected start and peak. This new solar cycle is forecast to be about the same strength as the solar cycle that just ended — both fairly weak. The new solar cycle is expected to peak in July 2025.

Learn more about the Sun’s cycle and how it affects our solar system at nasa.gov/sunearth.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.

See the Closest Ever Images of the Sun

Solar Orbiter just released its first scientific data — including the closest images ever taken of the Sun.

Launched on February 9, 2020, Solar Orbiter is a collaboration between the European Space Agency and NASA, designed to study the Sun up close. Solar Orbiter completed its first close pass of the Sun on June 15, flying within 48 million miles of the Sun’s surface.

This is already closer to the Sun than any other spacecraft has taken pictures (our Parker Solar Probe mission has flown closer, but it doesn’t take pictures of the Sun). And over the next seven years, Solar Orbiter will inch even closer to the Sun while tilting its orbit above the plane of the planets, to peek at the Sun’s north and south poles, which have never been imaged before.

Here’s some of what Solar Orbiter has seen so far.

The Sun up close

Solar Orbiter’s Extreme Ultraviolet Imager, or EUI, sees the Sun in wavelengths of extreme ultraviolet light that are invisible to our eyes.

EUI captured images showing “campfires” dotting the Sun. These miniature bright spots are over a million times smaller than normal solar flares. They may be the nanoflares, or tiny explosions, long thought to help heat the Sun’s outer atmosphere, or corona, to its temperature 300 times hotter than the Sun’s surface. It will take more data to know for sure, but one thing’s certain: In EUI’s images, these campfires are all over the Sun.

The Polar and Helioseismic Imager, or PHI, maps the Sun’s magnetic field in a variety of ways. These images show several of the measurements PHI makes, including the magnetic field strength and direction and the speed of flow of solar material.

PHI will have its heyday later in the mission, as Solar Orbiter gradually tilts its orbit to 24 degrees above the plane of the planets, giving it a never-before-seen view of the poles. But its first images reveal the busy magnetic field on the solar surface.

Studying space

Solar Orbiter’s instruments don’t just focus on the Sun itself — it also carries instruments that study the space around the Sun and surrounding the spacecraft.

The Solar and Heliospheric Imager, or SoloHi, looks out the side of the Solar Orbiter spacecraft to see the solar wind, dust, and cosmic rays that fill the space between the Sun and the planets. SoloHi captured the relatively faint light reflecting off interplanetary dust known as the zodiacal light, the bright blob of light in the right of the image. Compared to the Sun, the zodiacal light is extremely dim – to see it, SoloHi had to reduce incoming sunlight by a trillion times. The straight bright feature on the very edge of the image is a baffle illuminated by reflections from the spacecraft’s solar array.

This first data release highlights Solar Orbiter’s images, but its in situ instruments also revealed some of their first measurements. The Solar Wind Analyser, or SWA instrument, made the first dedicated measurements of heavy ions — carbon, oxygen, silicon, and iron — in the solar wind from the inner heliosphere.

Read more about Solar Orbiter’s first data and see all the images on ESA’s website.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

Weird Magnetic Behavior in Space

In between the planets, stars and other bits of rock and dust, space seems pretty much empty. But the super-spread out matter that is there follows a different set of rules than what we know here on Earth.

For the most part, what we think of as empty space is filled with plasma. Plasma is ionized gas, where electrons have split off from positive ions, creating a sea of charged particles. In most of space, this plasma is so thin and spread out that space is still about a thousand times emptier than the vacuums we can create on Earth. Even still, plasma is often the only thing out there in vast swaths of space — and its unique characteristics mean that it interacts with electric and magnetic fields in complicated ways that we are just beginning to understand.

Five years ago, we launched a quartet of satellites to study one of the most important yet most elusive behaviors of that material in space — a kind of magnetic explosion that had never before been adequately studied up close, called magnetic reconnection. Here are five of the ways the Magnetospheric Multiscale mission (MMS) has helped us study this intriguing magnetic phenomenon.

1. Seeing magnetic explosions up close

Magnetic reconnection is the explosive snapping and forging of magnetic fields, a process that can only happen in plasmas — and it's at the heart of space weather storms that manifest around Earth.

When the Sun launches clouds of solar material — which is also made of plasma — toward Earth, the magnetic field embedded within the material collides with Earth's huge global magnetic field. This sets off magnetic reconnection that injects energy into near-Earth space, triggering a host of effects — induced electric currents that can harm power grids, to changes in the upper atmosphere that can affect satellites, to rains of particles into the atmosphere that can cause the glow of the aurora.  

Though scientists had theorized about magnetic reconnection for decades, we'd never had a chance to study it on the small scales at which it occurs. Determining how magnetic reconnection works was one of the key jobs MMS was tasked with — and the mission quickly delivered. Using instruments that measured 100 times faster than previous missions, the MMS observations quickly determined which of several 50-year-old theories about magnetic reconnection were correct. It also showed how the physics of electrons dominates the process — a subject of debate before the launch.

2. Finding explosions in surprising new places

In the five years after launch, MMS made over a thousand trips around Earth, passing through countless magnetic reconnection events. It saw magnetic reconnection where scientists first expected it: at the nose of Earth's magnetic field, and far behind Earth, away from the Sun. But it also found this process in some unexpected places — including a region thought to be too tumultuous for magnetic reconnection to happen.

As solar material speeds away from the Sun in a flow called the solar wind, it piles up as it encounters Earth's magnetic field, creating a turbulent region called the magnetosheath. Scientists had only seen magnetic reconnection happening in relatively calm regions of space, and they weren't sure if this process could even happen in such a chaotic place. But MMS' precise measurements revealed that magnetic reconnection happens even in the magnetosheath.  

MMS also spotted magnetic reconnection happening in giant magnetic tubes, leftover from earlier magnetic explosions, and in plasma vortices shaped like ocean waves — based on the mission's observations, it seems magnetic reconnection is virtually ubiquitous in any place where opposing magnetic fields in a plasma meet.  

3. How energy is transferred

Magnetic reconnection is one of the major ways that energy is transferred in plasma throughout the universe — and the MMS mission discovered that tiny electrons hold the key to this process.

Electrons in a strong magnetic field usually exhibit a simple behavior: They spin tight spirals along the magnetic field. In a weaker field region, where the direction of the magnetic field reverses, the electrons go freestyle — bouncing and wagging back and forth in a type of movement called Speiser motion.

Flying just 4.5 miles apart, the MMS spacecraft measured what happens in a magnetic field with intermediate strength: These electrons dance a hybrid, meandering motion — spiraling and bouncing about before being ejected from the region. This takes away some of the magnetic field’s energy.

4. Surpassing computer simulations

Before we had direct measurements from the MMS mission, computer simulations were the best tool scientists had to study plasma's unusual magnetic behavior in space. But MMS' data has revealed that these processes are even more surprising than we thought — showing us new electron-scale physics that computer simulations are still trying to catch up with. Having such detailed data has spurred theoretical physicists to rethink their models and understand the specific mechanisms behind magnetic reconnection in unexpected ways. 

5. In deep space & nuclear reactions

Although MMS studies plasma near Earth, what we learn helps us understand plasma everywhere. In space, magnetic reconnection happens in explosions on the Sun, in supernovas, and near black holes.

These magnetic explosions also happen on Earth, but only under the most extreme circumstances: for example, in nuclear fusion experiments. MMS' measurements of plasma's behavior are helping scientists better understand and potentially control magnetic reconnection, which may lead to improved nuclear fusion techniques to generate energy more efficiently.

This quartet of spacecraft was originally designed for a two-year mission, and they still have plenty of fuel left — meaning we have the chance to keep uncovering new facets of plasma's intriguing behavior for years to come. Keep up with the latest on the mission at nasa.gov/mms.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

Taking Solar Science to New Heights

We're on the verge of launching a new spacecraft to the Sun to take the first-ever images of the Sun's north and south poles!

Credit: ESA/ATG medialab

Solar Orbiter is a collaboration between the European Space Agency (ESA) and NASA. After it launches — as soon as Feb. 9 — it will use Earth's and Venus's gravity to swing itself out of the ecliptic plane — the swath of space, roughly aligned with the Sun’s equator, where all the planets orbit. From there, Solar Orbiter's bird’s eye view will give it the first-ever look at the Sun's poles.

Credit: ESA/ATG medialab

The Sun plays a central role in shaping space around us. Its massive magnetic field stretches far beyond Pluto, paving a superhighway for charged solar particles known as the solar wind. When bursts of solar wind hit Earth, they can spark space weather storms that interfere with our GPS and communications satellites — at their worst, they can even threaten astronauts.

To prepare for potential solar storms, scientists monitor the Sun’s magnetic field. But from our perspective near Earth and from other satellites roughly aligned with Earth's orbit, we can only see a sidelong view of the Sun's poles. It’s a bit like trying to study Mount Everest’s summit from the base of the mountain.

Solar Orbiter will study the Sun's magnetic field at the poles using a combination of in situ instruments — which study the environment right around the spacecraft — and cameras that look at the Sun, its atmosphere and outflowing material in different types of light. Scientists hope this new view will help us understand not only the Sun's day-to-day activity, but also its roughly 11-year activity cycles, thought to be tied to large-scales changes in the Sun's magnetic field.

Solar Orbiter will fly within the orbit of Mercury — closer to our star than any Sun-facing cameras have ever gone — so the spacecraft relies on cutting-edge technology to beat the heat.

Credit: ESA/ATG medialab

Solar Orbiter has a custom-designed titanium heat shield with a calcium phosphate coating that withstands temperatures more than 900 degrees Fahrenheit — 13 times the solar heating that spacecraft face in Earth orbit. Five of the cameras look at the Sun through peepholes in that heat shield; one observes the solar wind out the side.

Over the mission’s seven-year lifetime, Solar Orbiter will reach an inclination of 24 degrees above the Sun’s equator, increasing to 33 degrees with an additional three years of extended mission operations. At closest approach the spacecraft will pass within 26 million miles of the Sun.

Solar Orbiter will be our second major mission to the inner solar system in recent years, following on August 2018’s launch of Parker Solar Probe. Parker has completed four close solar passes and will fly within 4 million miles of the Sun at closest approach.

Solar Orbiter (green) and Parker Solar Probe (blue) will study the Sun in tandem. 

The two spacecraft will work together: As Parker samples solar particles up close, Solar Orbiter will capture imagery from farther away, contextualizing the observations. The two spacecraft will also occasionally align to measure the same magnetic field lines or streams of solar wind at different times.

Watch the launch

The booster of a United Launch Alliance Atlas V rocket that will launch the Solar Orbiter spacecraft is lifted into the vertical position at the Vertical Integration Facility near Space Launch Complex 41 at Cape Canaveral Air Force Station in Florida on Jan. 6, 2020. Credit: NASA/Ben Smegelsky

Solar Orbiter is scheduled to launch on Feb. 9, 2020, during a two-hour window that opens at 11:03 p.m. EST. The spacecraft will launch on a United Launch Alliance Atlas V 411 rocket from Space Launch Complex 41 at Cape Canaveral Air Force Station in Florida.

Launch coverage begins at 10:30 p.m. EST on Feb. 9 at nasa.gov/live. Stay up to date with mission at nasa.gov/solarorbiter!

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

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.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com