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Magnetic Field - Blog Posts
Do You Love the Color of the Sun?
Get dazzled by the true spectrum of solar beauty. From fiery reds to cool blues, explore the vibrant hues of the Sun in a mesmerizing color order. The images used to make this gradient come from our Solar Dynamics Observatory. Taken in a variety of wavelengths, they give scientists a wealth of data about the Sun. Don't miss the total solar eclipse crossing North America on April 8, 2024. (It's the last one for 20 years!) Set a reminder to watch with us.
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.
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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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Completely invisible, yet unbelievably influential. 💫
According to new research from our Stratospheric Observatory for Infrared Astronomy (SOFIA), spiral galaxies like the Milky Way are shaped by magnetic fields. These magnetic fields are invisible to the human eye.
However, by combining imagery from our Hubble Space Telescope, the Nuclear Spectroscopic Array and the Sloan Digital Sky Survey, the magnetic fields become apparent. In this image, scientists measured the magnetic fields along the spiral arms of the galaxy called NGC 1068. The fields are shown as streamlines that closely follow the circling arms.
Image Credit: NASA/SOFIA; NASA/JPL-Caltech/Roma Tre Univ.
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High-Flying Spacecraft Finish 1000th Lap Around Earth!
The quadruplet spacecraft of the Magnetospheric Multiscale mission have just returned from their first adventure into the solar wind — sailing through the most intense winds of their journey so far.
These spacecraft were designed to study Earth’s giant magnetic system, which shields our planet from the majority of the Sun’s constant outflow of material — what we call the solar wind.
Usually, the Magnetospheric Multiscale spacecraft — MMS for short — take their measurements from inside Earth’s protective magnetic environment, the magnetosphere. But in February and March, the MMS spacecraft ventured beyond this magnetic barrier to measure that solar wind directly — a feat that meant they had to change up how they fly in a whole new way.
Outside of Earth's protective magnetic field, the spacecraft were completely immersed in the particles and magnetic fields of the solar wind. As they flew through the stream of material, the spacecraft traced out a wake behind each instrument, just like a boat in a river. To avoid measuring that wake, each spacecraft was tilted into the wind so the instruments could take clean measurements of the pristine solar wind, unaffected by the wake.
Within the magnetosphere, the MMS spacecraft fly in a pyramid-shaped formation that allows them to study magnetic fields in 3D. But to study the solar wind, the mission team aligned spacecraft in a straight line at oddly spaced intervals. This string-of-pearls formation gave MMS a better look at how much the solar wind varies over different scales.
Because the four spacecraft fly so close together, MMS relies on super-accurate navigation from GPS satellites. This venture into the solar wind took the spacecraft even farther from Earth than before, so MMS broke its own world record for highest-ever GPS fix. The spacecraft were over 116,000 miles above Earth — about halfway to the Moon — and still using GPS!
Now, just in time for the 1,000th orbit of their mission — which adds up to 163 million miles flown! — the spacecraft are back in Earth's magnetosphere, flying in their usual formation to study fundamental processes within our planet’s magnetic field.
Keep up with the latest MMS research at nasa.gov/mms, on Twitter @NASASun or with NASA Sun Science on Facebook.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com
5 Facts About Earth's Radiation Donuts 🍩
Did you know that our planet is surrounded by giant, donut-shaped clouds of radiation?
Here's what you need to know.
1. The radiation belts are a side effect of Earth's magnetic field
The Van Allen radiation belts exist because fast-moving charged particles get trapped inside Earth's natural magnetic field, forming two concentric donut-shaped clouds of radiation. Other planets with global magnetic fields, like Jupiter, also have radiation belts.
2. The radiation belts were one of our first Space Age discoveries
Earth's radiation belts were first identified in 1958 by Explorer 1, the first U.S. satellite. The inner belt, composed predominantly of protons, and the outer belt, mostly electrons, would come to be named the Van Allen Belts, after James Van Allen, the scientist who led the charge designing the instruments and studying the radiation data from Explorer 1.
3. The Van Allen Probes have spent six years exploring the radiation belts
In 2012, we launched the twin Van Allen Probes to study the radiation belts. Over the past six years, these spacecraft have orbited in and out of the belts, providing brand-new data about how the radiation belts shift and change in response to solar activity and other factors.
4. Surprise! Sometimes there are three radiation belts
Shortly after launch, the Van Allen Probes detected a previously-unknown third radiation belt, created by a bout of strong solar activity. All the extra energy directed towards Earth meant that some particles trapped in our planet's magnetic field were swept out into the usually relatively empty region between the two Van Allen Belts, creating an additional radiation belt.
5. Swan song for the Van Allen Probes
Originally designed for a two-year mission, the Van Allen Probes have spent more than six years collecting data in the harsh radiation environment of the Van Allen Belts. In spring 2019, we're changing their orbit to bring the perigee — the part of the orbit where the spacecraft are closest to Earth — about 190 miles lower. This ensures that the spacecraft will eventually burn up in Earth's atmosphere, instead of orbiting forever and becoming space junk.
Because the Van Allen Probes have proven to be so hardy, they'll continue collecting data throughout the final months of the mission until they run out of fuel. As they skim through the outer reaches of Earth's atmosphere, scientists and engineers will also learn more about how atmospheric oxygen can degrade satellite measurements — information that can help build better satellites in the future.
Keep up with the latest on the mission on Twitter, Facebook or nasa.gov/vanallenprobes.
Extreme Science: Launching Sounding Rockets from The Arctic
This winter, our scientists and engineers traveled to the world's northernmost civilian town to launch rockets equipped with cutting-edge scientific instruments.
This is the beginning of a 14-month-long campaign to study a particular region of Earth's magnetic field — which means launching near the poles. What's it like to launch a science rocket in these extreme conditions?
Our planet is protected by a natural magnetic field that deflects most of the particles that flow out from the Sun — the solar wind — away from our atmosphere. But near the north and south poles, two oddities in Earth's magnetic field funnel these solar particles directly into our atmosphere. These regions are the polar cusps, and it turns out they're the ideal spot for studying how our atmosphere interacts with space.
The scientists of the Grand Challenge Initiative — Cusp are using sounding rockets to do their research. Sounding rockets are suborbital rockets that launch to a few hundred miles in altitude, spending a few minutes in space before falling back to Earth. That means sounding rockets can carry sensitive instruments above our atmosphere to study the Sun, other stars and even distant galaxies.
They also fly directly through some of the most interesting regions of Earth's atmosphere, and that's what scientists are taking advantage of for their Grand Challenge experiments.
One of the ideal rocket ranges for cusp science is in Ny-Ålesund, Svalbard, off the coast of Norway and within the Arctic circle. Because of its far northward position, each morning Svalbard passes directly under Earth's magnetic cusp.
But launching in this extreme, remote environment puts another set of challenges on the mission teams. These launches need to happen during the winter, when Svalbard experiences 24/7 darkness because of Earth's axial tilt. The launch teams can go months without seeing the Sun.
Like for all rocket launches, the science teams have to wait for the right weather conditions to launch. Because they're studying upper atmospheric processes, some of these teams also have to wait for other science conditions, like active auroras. Auroras are created when charged particles collide with Earth’s atmosphere — often triggered by solar storms or changes in the solar wind — and they're related to many of the upper-atmospheric processes that scientists want to study near the magnetic cusp.
But even before launch, the extreme conditions make launching rockets a tricky business — it's so cold that the rockets must be encased in styrofoam before launch to protect them from the low temperatures and potential precipitation.
When all is finally ready, an alarm sounds throughout the town of Ny-Ålesund to alert residents to the impending launch. And then it's up, up and away! This photo shows the launch of the twin VISIONS-2 sounding rockets on Dec. 7, 2018 from Ny-Ålesund.
These rockets are designed to break up during flight — so after launch comes clean-up. The launch teams track where debris lands so that they can retrieve the pieces later.
The next launch of the Grand Challenge Initiative is AZURE, launching from Andøya Space Center in Norway in March 2019.
For even more about what it's like to launch science rockets in extreme conditions, check out one scientist's notes from the field: https://go.nasa.gov/2QzyjR4
For updates on the Grand Challenge Initiative and other sounding rocket flights, visit nasa.gov/soundingrockets or follow along with NASA Wallops and NASA heliophysics on Twitter and Facebook.
@NASA_Wallops | NASA’s Wallops Flight Facility | @NASASun | NASA Sun Science