The diameter of the sun is approximately 864,575.9 miles. This distance describes a straight line going through the center of the sun, from one side to the next. To get an idea about how massive the sun truly is, the diameter of Earth is 7,917.5 miles.
The Shape and Size of the Sun
The largest object in the solar system is the sun. Approximately 99.8 percent of the system’s mass is held by the sun. You can see by looking at the differences in diameter above that compared to the Earth, the sun is approximately 109 times the diameter. This means that inside the sun, you could fit about one million Earths.
When you look at the shape of the sun, it is almost a perfect sphere. There is only a difference of 6.2 miles between the polar diameter and the equatorial diameter. The total circumference is approximately 2,713,406 miles.
Now, while in this solar system, it is the biggest structure, it is just average in size when you look at other stars elsewhere in space. For example, the star Betelgeuse is nearly 700 times larger than the sun. When it comes to brightness, it is nearly 14,000 times brighter.
Fun Facts About the Sun
The sun is a type of star and it is located approximately 93 million miles from Earth. Its energy travels outward. The core of this start is made up of different dense and hot gases. The temperature is approximately 27 million degrees Fahrenheit.
You can see that the sun is absolutely massive, especially compared to Earth. Compared to the moon associated with Earth that comes in at 2,159 miles in diameter, the sun is certainly one of the largest structures that you can see from where you are on Earth.
On September 6th, September 7th, and the 8th NASA has reported massive solar flares from active regions of the sun.
The solar flares are the most powerful recorded flares since 2006 and are causing minor radio blackouts as well as spectacular aurora visible in locations not normally seen.
Here is the timeline of events for the recent solar flares:
Today (sep 8) the sun emitted a mid-level solar flare that peaked at at 3:49 a.m. EDT. You can see a visualization of that flare below.
On September 7th, our sun showed two mid-level solar flares the first peaked at 6:15 a.m. EDT. The second, larger flare, peaked at 10:36 a.m. EDT. These are the fourth noticeable flares in the same active region since Sept. 4.
You can see how these flares are effecting our planet at NOAA’s Space Weather Prediction Center.
On September 6th, NASA captured the first two significant solar flares, the first peaked at 5:10 a.m. EDT and the second, larger flare, peaked at 8:02 a.m. EDT.
Below you can take a look at how the flares are effecting visible aurora.
The sun is a massive ball of gas and it is hot. When you step outside on a warm summer day, you can feel the heat radiating from it. This often makes it feel closer to Earth than it really is.
Looking at a Trip to the Sun
The sun is approximately 93 million miles away from Earth. To put this into perspective, it would take you about 177 years to reach the sun in a car if you were driving at 60 miles per hour and you did not stop once. It would take about 19 years if you were in a commercial jet that was flying at approximately 550 miles per hour without stopping.
However, due to the fact that the surface of the sun is approximately 10,340 degrees Fahrenheit, it is not possible for humans to make the trip. Since the trip would be long and something a human could not survive and you’d definitely run out of gas with nowhere to stop, scientists have found ways to get digital information about this ball of gas. There are special robotic probes that have been sent to the sun and the surrounding area. This has allowed scientists to monitor the weather patterns and behaviors associated with the sun.
The fastest moving space vehicles are referred to as Helios probes. They have orbited around the sun to gather information about it. These probes travel at approximately 157 miles per hour and they make no stops on the way from Earth to the sun. They reached their destination in about 24.7 days.
Getting to the sun would certainly be an adventure. However, it is not possible due to its composition. No human would be able to survive it and there is no spacecraft so far that would be able to resist the treacherous conditions.
You walk outside during the morning or afternoon and you are greeted with bright light thanks to the sun. However, how much do you know about it? This glowing sphere of hot gas is incredibly interesting and there is so much that people can learn about it.
Does the Sun Rotate?
While at a considerably slower pace than many other solar system elements, the sun does rotate, or spin. However, it does this in a different way because unlike the planets which are solid, the sun is a giant ball of gas. When you compare the poles and the equator of the sun, you will learn that the equator area spins faster than the pole area.
At the equator, the sun rotates approximately one time every 24 days. However, near its poles, it only rotates approximately one time every 35 days. This information is something that scientists learned by examining the sun spots and making an observation concerning their motion. They also gleaned information about this by looking at other solar features and how they moved across the sun.
Why Does the Sun Rotate Differently Than Earth?
The Earth completes one rotation every 24 hours. This means that it moves faster than the sun and this is largely due to the fact that the Earth is solid. Since the sun is basically a flaming gas ball, it is more difficult to pinpoint its rotation. NASA says that this is because the sun does not have to rotate in a rigid manner like the solid moon and planets do.
Now you have more information about some of the basics concerning the sun. With this base of knowledge, it will be easier to build on it and increase how much you know about one of the most important elements in the solar system.
2017’s total solar eclipse came and went within a matter of hours, but it was a spectacle that most who watched will never forget. And one that is causing some issues the day after.
We won’t see our next total solar eclipse again until April 8th 2024, so until then we’ll need to bask in the glory of images produced by yesterday’s lunar/solar event.
Below you can find 19 stunning hand selected images from across the globe.
Google trends often provides hilarious insights. A momentous event like a Total Solar Eclipse was sure to produce a wide variation of search opportunities. The most interesting trend for the eclipse was revealed after the event, rather than before…
Predictably, a large batch of individuals across the world did not heed the advice of scientists; millions across the globe watched the solar eclipse without the aid of protective sunglasses, including the President of The United States.
Spikes in search terms after the eclipse exemplify why you should never look at an eclipse without the aid of proper viewing equipment. Just after August 2017’s total solar eclipse, searches for the term “eclipse headache” peaked in google.
Eclipse headache wasn’t the only fallout for viewers without protection. Google also saw a large spike in the search term for “eyes hurt”, “looking at sun”, “I looked at the sun”, and “I looked at the sun for a few seconds”. All of these are adjacent search terms that show variations of the problem.
If you wondered what’s the worst that could happen if you didn’t use protective glasses, we’ll be blunt; you can damage your retinas beyond repair, so it’s important to never look at the sun without proper protection.
If you did look at the eclipse without glasses, and are experiencing any issues with your eyes you should go see an optometrist.
Captured via high speed camera, in this video you can see the International Space Station transiting the sun during today’s total eclipse.
Station transits sun at 5 miles per second in video taken at 1,500 frames per second with high-speed camera from Banner, Wyoming. pic.twitter.com/x6NNvCc0Af
— Intl. Space Station (@Space_Station) August 21, 2017
Watch NASA’s live stream of the 2017 total solar eclipse as it passes across the country.
Below you can take a look at the path of totality:
Everyone knows that you should not look at the sun!
Not with your naked eye, not with sunglasses and certainly not with binoculars or with a telescope. Our sun might be just an ordinary star, but it’s extremely close to us — about 269,000 times closer than the next nearest star. This makes the sun very, very bright.
Everyone knows that you should not look at the sun. But what about during an eclipse? This situation will confront us on Aug. 21, when the entirety of North America, along with parts of South America, Africa, Europe and eastern Russia, will experience a solar eclipse.
For the vast majority of viewers, including anyone in any part of Canada, the eclipse will be a partial one. This means that the moon will block out part of the face of the sun but leave the rest of it unchanged.
If you’re under the path of the partial eclipse — even somewhere where the sun is 99 per cent concealed — you still should not look at the sun with the unaided eye. Even one-hundredth of the sun’s normal brightness is enough to permanently damage your eyesight.
Instead, you can safely watch the action through special eclipse glasses (make sure they’re ISO certified and from a reliable supplier), through a simple home-made pinhole camera or even by looking at the shadows cast by tree leaves or by a kitchen colander.
For some lucky viewers in parts of 14 U.S. states, a total solar eclipse awaits on Aug. 21. This will be far more exciting than a mere partial eclipse. For maybe as long as two minutes, depending on your exact location, the sun will disappear completely behind the moon. The temperature will drop, the stars will come out, and the birds will think evening has come.
If you are under the path of the total eclipse, you’ll likely have more than an hour of partial eclipse both before and after the exciting moment of totality. During the partial phases, the usual rules apply: Wear your eclipse glasses or use your colander, but don’t look at the sun unaided!
However, when the time finally arrives and when the sky goes dark, it will finally be safe to look. Take off your glasses, stare at the sun with your unaided eyes, and soak up a remarkable cosmic moment.
During the total eclipse, it is completely safe to look at the sun without any equipment at all. And what a sight it will be.
Revealed, just for a moment, will be the sun’s glorious corona, the faint tendrils of ultra-hot gas that stream off the sun’s blazing surface. This is not to be missed. If you leave your eclipse glasses on, you won’t see anything.
After a minute or two, the total eclipse will be over, the skies will lighten and special safety precautions must once again be taken. But those who experience totality will be left with memories of an otherwise hidden view of the Universe, a brief glimpse of our life-giving sun unlike any other.
My favourite science news is the stuff that changes the way I think about the world and our place in the universe. Many dinosaurs were covered in feathers; there’s a planet in the habitable zone around the nearest star in the night sky; the universe is expanding faster and faster but no one yet knows why.
Now there’s a genuinely awe-inspiring and amazing discovery that really has changed the way I think about our solar system. A team of astronomers have discovered that the core of our sun rotates about four times faster than the surface. It’s in the middle of our solar system, on our cosmic doorstep, so how could we have missed that before? And why is it important?
It’s not easy to work out what’s inside the sun – you can’t send a probe inside to fly about. The trick is to use seismology in a similar way that earthquakes are monitored. It’s possible to work out what’s inside the Earth under our feet, right to the core, without digging, by measuring how “seismic waves” (vibrations from earthquakes) pass through the Earth. We know from this that most of it is not liquid, contrary to popular belief, because of the so-called “S-waves”.
These waves wiggle side to side, perpendicular to the direction of travel. They can only exist in a solid, and they pass through most of the Earth. Pressure waves or “P-waves”, where the wiggle is parallel to the direction of travel (like sound), can also go through liquids. From the S-waves and P-waves, we know the Earth has a solid core, a liquid outer core, and a solid mantle and crust.
To work out what’s inside the sun, the ESA/NASA Solar and Heliospheric Observatory (SOHO for short) team has also used seismology to look at waves in the sun. In this context, it’s called helioseismology. However, you can’t stick an earthquake-monitor on the sun’s surface, so scientists use the “Doppler effect” to measure waves at the sun’s surface. The Doppler effect is the stretching or squashing of waves because of motion, whether it’s motion of the thing emitting the wave or motion of the thing receiving the wave.
In this case, sound waves wash through the sun and reach the surface, and so the sun’s surface moves towards or away from SOHO. The sun’s surface also gives off light, and the motion means the light waves are squashed or stretched. This change in wavelength is what the SOHO spacecraft measures, and the team translates this into information about the sound waves that reached the surface.
The SOHO team spent 16 years monitoring the sound waves passing through the sun. Their careful and delicate analysis of the data managed to tease out something else going on: buoyant blobs of gas bobbing around deep inside the sun, in a phenomenon called “G-waves” where G is short for gravity. (These are completely different to the “gravitational waves” from deep space discovered by LIGO, though.)
The sound waves that pass through the sun are subtly changed in pitch by this bobbing around deep inside. The evidence from this data looks very clear: the core of the sun is rotating about once a week, instead of about once a month at the surface.
This was a surprising, unexpected discovery. It’s not yet understood why the sun’s core has this faster spin. Perhaps it’s something that was imprinted into the structure of the sun early in its life, caused by the action of magnetic fields inside the sun moving charged gas along magnetic field lines and redistributing it. This would make the sun’s core a cryptic relic of the ancient history of our solar system, at a time when our planet Earth was still being formed. Understanding this is the next challenge, but either way, there is now a wonderful new way to work out what is happening deep inside the sun.
There’s lots of very good practical reasons for funding space science: it pump-primes very high-tech industry, and every €1 invested in space returns an average €6 to the wider economy. But for me the best rationale isn’t economic, it’s cultural. We seek out this knowledge because it’s intrinsically important, and because it’s beautiful, and because these achievements are what a civilisation is remembered for in the end.
I am confident that we will be remembered as the culture that discovered many dinosaurs were covered in feathers, and that there’s a planet in the habitable zone around the nearest star in the night sky, and that the universe is expanding faster and faster (but no one yet knows why) – and that hidden deep inside our sun, the core is spinning four times faster than its surface.
On July 5, 2017, NASA’s Solar Dynamics Observatory watched an active region — an area of intense and complex magnetic fields — rotate into view on the Sun. The satellite continued to track the region as it grew and eventually rotated across the Sun and out of view on July 17.
With their complex magnetic fields, sunspots are often the source of interesting solar activity: During its 13-day trip across the face of the Sun, the active region — dubbed AR12665 — put on a show for NASA’s Sun-watching satellites, producing several solar flares, a coronal mass ejection and a solar energetic particle event. Watch the video below to learn how NASA’s satellites tracked the sunspot over the course of these two weeks.
Such sunspots are a common occurrence on the Sun, but less frequent at the moment, as the Sun is moving steadily toward a period of lower solar activity called solar minimum — a regular occurrence during its approximately 11-year cycle. Scientists track such spots because they can help provide information about the Sun’s inner workings. Space weather centers, such as NOAA’s Space Weather Prediction Center, also monitor these spots to provide advance warning, if needed, of the radiation bursts being sent toward Earth, which can impact our satellites and radio communications.
On July 9, a medium-sized flare burst from the sunspot, peaking at 11:18 a.m. EDT. Solar flares are explosions on the Sun that send energy, light and high-speed particles out into space — much like how earthquakes have a Richter scale to describe their strength, solar flares are also categorized according to their intensity. This flare was categorized as an M1. M-class flares are a tenth the size of the most intense flares, the X-class flares. The number provides more information about its strength: An M2 is twice as intense as an M1, an M3 is three times as intense and so on.
Days later, on July 14, a second medium-sized, M2 flare erupted from the Sun. The second flare was long-lived, peaking at 10:09 a.m. EDT and lasting over two hours.
This was accompanied by another kind of solar explosion called a coronal mass ejection, or CME. Solar flares are often associated with CMEs — giant clouds of solar material and energy. NASA’s Solar and Heliospheric Observatory, or SOHO, saw the CME at 9:36 a.m. EDT leaving the Sun at speeds of 620 miles per second and eventually slowing to 466 miles per second.
Following the CME, the turbulent active region also emitted a flurry of high-speed protons, known as a solar energetic particle event, at 12:45 p.m. EDT.
Research scientists at the Community Coordinated Modeling Center — located at NASA’s Goddard Space Flight Center in Greenbelt, Maryland — used these spacecraft observations as input for their simulations of space weather throughout the solar system. Using a model called ENLIL, they are able to map out and predict whether the solar storm will impact our instruments and spacecraft, and send alerts to NASA mission operators if necessary.
By the time the CME made contact with Earth’s magnetic field on July 16, the sunspot’s journey across the Sun was almost complete. As for the solar storm, it took this massive cloud of solar material two days to travel 93 million miles to Earth, where it caused charged particles to stream down Earth’s magnetic poles, sparking enhanced aurora.
The sun is a middle-aged star at the center of our solar system. Everything in our known solar system revolves around the sun. Planets, asteroids, comets and more. It formed approximately 4.6 billon years ago and is expected to remain stable for the next five billion years.
How Far Is The Sun From Earth
On average the sun is 149.6 million km (or 92 million miles) from Earth. We say ‘average’ because the orbit of the star varies it’s distance from our home planet. When it is at it’s closest, the sun is 147.1 million km (91.4 million miles) from Earth. In the winter, the Sun is at it’s closest to the planet, in the northern hemisphere. This is known as the perihelion. At it’s furthest, it’s 152.1 million km (94.5 million miles) from us. This occurs during the beginning of July and is known as the aphelion.
The Earth’s Elliptical Orbit
The Earth has an elliptical orbit. This causes the varied distances described above. You can describe this orbit as more of an oval or an ellipse, rather than a stable circle.
How Close Could You Get To The Sun And Survive?
Here’s an interesting fun fact for you. Technically, with today’s current technology, we could get safely within 1.3 million miles of the sun. That’s an astounding 96% of the distance from here to our host star. And here’s how we would do it:
The space shuttle has a heat shield resistant up to 4,700° fahrenheit to allow it to re-enter earth safely and survive the frictions of our atmosphere. If we were to cover the shuttle entirely in this material, that would allow us to come within 1.3 million miles safely. At 1.3 million miles the temperature of the sun is approximately equivalent to the heat shield’s resistance. At the sun’s surface however, the coolest temperatures exceed 9,940°F, and that’s really hot.
This summer, a flight will track the solar eclipse as it moves across the country. Alaskan Airlines is poised to provide a unique experience for astronomy enthusiasts according to Sangita Woerner, Alaska’s vice president of marketing; “As an airline, we are in a unique position to provide a one-of-a-kind experience for astronomy enthusiasts. Flying high above the Pacific Ocean will not only provide one of the first views, but also one of the best.”
On August 21st, an Alaskan Airlines flight will take off from Portland, Oregon at 7:30 am local time and fly south down the west coast of the U.S. giving viewers a once in a lifetime view of the solar eclipse. This isn’t the first time the airline has done something of the sort; last year it flew passengers over Honolulu to watch a similar eclipse.
Currently the flight is in ‘invite-only’ status, but Alaskan Airlines will be offering up seats as prizes to followers of it’s social accounts.
“As an airline, we are in a unique position to provide a one-of-a-kind experience for astronomy enthusiasts. Flying high above the Pacific Ocean will not only provide one of the first views, but also one of the best.”
Admittedly, it will be a long-shot to get a chance to view the eclipse from the flight, but thankfully the 2017 eclipse is predicted to be visible across most of the U.S. as you can see in the diagram below.
It is the first coast-to-coast total eclipse since 1918.
Weather permitting, astronomy enthusiasts can watch as the moon’s 70-mile (113-km) wide shadow crosses the country, starting at 10:15 a.m. PDT (1715 GMT) around Lincoln Beach, Oregon, and ending at 2:49 p.m. EDT (1849 GMT) in McClellanville, South Carolina.
CAPE CANAVERAL, Fla. (Reuters) – Two months before the first total solar eclipse to cross the continental United States in a century, NASA is expected to detail its plans to study and promote a celestial show that will darken skies from Oregon to South Carolina.
During the Aug. 21 eclipse, the moon will pass between the sun and Earth, blocking the face of the sun and leaving only its outer atmosphere, or corona, visible in the sky.
It is the first coast-to-coast total eclipse since 1918.
Weather permitting, astronomy enthusiasts can watch as the moon’s 70-mile (113-km) wide shadow crosses the country, starting at 10:15 a.m. PDT (1715 GMT) around Lincoln Beach, Oregon, and ending at 2:49 p.m. EDT (1849 GMT) in McClellanville, South Carolina.
The U.S. National Aeronautics and Space Administration will discuss several solar physics and Earth science experiments to be conducted during the eclipse in a news conference on Wednesday afternoon. The agency also plans live broadcasts during the eclipse from dozens of locations along the path.
Total solar eclipses occur somewhere on Earth every year or so, but most cast their shadow over oceans or remote land. The last time a part of the contiguous U.S. saw a total eclipse was in 1979.
All of North America will experience a partial eclipse, though the difference between a full and partial eclipse is “literally the difference between night and day,” said astronomer Rick Fienberg of the American Astronomical Society.
He noted that even a 99 percent eclipse will not reveal the sun’s corona. And during a total eclipse, the temperature drops and the horizon is ringed by the colors of sunset.
“The sky gets deep twilight blue and bright stars and planets come out,” Fienberg said. “Animals and birds behave strangely, like it’s the end of the day.”
More than 12 million Americans live in the path of the full eclipse, said astronomer Angela Speck, who heads the society’s eclipse public outreach campaign.
The entire U.S. population, except for northern Maine, lives within 900 miles of the full eclipse’s path.
Travel groups and many scientists will be heading to Oregon’s northwest desert, which has the best odds of favorable weather for viewing, according to the website eclipsophile.com.
Experts caution that the only safe time to look at the sun without special eclipse glasses is during totality when the surface of the sun is completely blocked by the moon.
(By Irene Klotz, Editing by Letitia Stein and Phil Berlowitz)
CAPE CANAVERAL, Fla. (Reuters) – A U.S. spacecraft set to launch next year will make a series of unprecedented dives in the sun’s scorching atmosphere to see how the star works and what can be done to better predict space weather events on Earth, scientists said on Wednesday.
The Parker Solar Probe will have to survive temperatures as high as 2,500 Fahrenheit (1,371 Celsius), impacts by supersonic particles and powerful radiation as it circles as close as 4 million miles (7 million km) to the sun.
Data sent back to Earth some 89 million miles (1.4 billion km) away will help scientists figure out why the sun’s atmosphere, or corona, is hotter than its surface.
“We’re going to be seven times closer (to the sun) than any other mission has ever been,” project scientist Nicola Fox, with Johns Hopkins University Applied Physics Laboratory in Maryland, said during a broadcast on NASA TV.
The mission, formerly known as the Solar Probe Plus, was approved in 2014. On Wednesday, the spacecraft was renamed to honor University of Chicago physicist Eugene Parker, who in 1958 correctly predicted the existence of the solar wind, a continuous stream of charged particles that come off the sun and permeate the solar system.
“It was a fundamental insight that forever changed the way in which we understood the sun, the heliosphere and in general interplanetary space,” said Eric Isaacs, executive vice president for research, innovation and national laboratories at the University of Chicago.
The spacecraft, designed and built by the Johns Hopkins University laboratory, is scheduled to launch in July 2018 and fly around Venus seven times to get itself into orbit around the sun in December 2024. NASA is paying about $1.5 billion to build and launch the spacecraft.
The probe is expected to orbit the sun 24 times, edging closer on each pass. The size of a small car, it will be outfitted with five science instruments to measure and sample the sun’s corona.
In addition to expanding knowledge of stellar physics, the information is expected to help engineers design better instruments and techniques for predicting solar storms and other events that can cripple satellites, disrupt power grids and affect aircraft travel on Earth.
“We want to measure the environment there and find what the heating processes really are that make the corona hot and accelerate the solar wind,” said NASA chief scientist Thomas Zurbuchen.
(Reporting by Irene Klotz; Editing by Colleen Jenkins and Lisa Shumaker)
Tomorrow, at 11 a.m. EDT, NASA will be making an announcement about a groundbreaking mission to fly directly into our Sun’s atmosphere.
NASA will be launching a probe named ‘Solar Probe Plus‘ in 2018. It will orbit within four million miles of the sun’s surface and face the most extreme conditions any spacecraft has ever encountered. While in orbit, it will face temperatures of 1,370°C (2,500°F), it’s able to do this by making use of a 4.5 inch thick heat resistant carbon composite shield.
In NASA’s words, the purpose of the mission is to ‘explore the sun’s outer atmosphere and make critical observations that will answer decades-old questions about the physics of how stars work. The resulting data will improve forecasts of major space weather events that impact life on Earth, as well as satellites and astronauts in space.’
Understanding the Sun is also an economic issue, one recent study by the National Academy of Sciences estimated that without advance warning a huge solar event could cause two trillion dollars in damage in the US alone, and the eastern seaboard of the US could be without power for a year.
Be sure to tune in tomorrow for the announcement. Below you can find a diagram of Solar Probe Plus’ proposed orbit and functionality.
For 15 days, dating back to March 7th, our sun has been spotless as observed by NASA’s Solar Dynamics Observatory (SDO).
A NASA statement notes “this is the longest stretch of spotlessness since the last solar minimum in April 2010, indicating the solar cycle is marching on toward the next minimum, which scientists predict will occur between 2019-2020.”
Our Sun goes through cycles, specifically 11 year solar cycles between “solar maximums” and “solar minimums”. At its most active (during a solar maximum period) our sun can have hundreds of sunspots. During a minimum, such as the one we’re observing at the current moment, there can be none.
Sunspots are temporary phenomena on the photosphere of the Sun that appear as dark spots compared to surrounding regions. They are areas of reduced surface temperature caused by concentrations of magnetic field flux that inhibit convection. Sunspots usually appear in pairs of opposite magnetic polarity.
We’ve yet to understand the solar cycle’s significance, but what we do know about it is that it can effect the Sun’s activity and thus the particles it sends towards Earth. This can effect aurorae here on our planet, being less vibrant during solar minimums, and more vibrant during maximums (during maximums, aurorae can appear red).
We’ve been measuring the solar cycle since Johann Rudolf Wolf in 1755. We’re currently in the 24th recorded solar cycle which is believed the be the weakest cycle since 1906.
An international science team says NASA’s Fermi Gamma-ray Space Telescope has observed high-energy light from solar eruptions located on the far side of the sun, which should block direct light from these events. This apparent paradox is providing solar scientists with a unique tool for exploring how charged particles are accelerated to nearly the speed of light and move across the sun during solar flares.
“Fermi is seeing gamma rays from the side of the sun we’re facing, but the emission is produced by streams of particles blasted out of solar flares on the far side of the sun,” said Nicola Omodei, a researcher at Stanford University in California. “These particles must travel some 300,000 miles within about five minutes of the eruption to produce this light.”
Omodei presented the findings on Monday, Jan. 30, at the American Physical Society meeting in Washington, and a paper describing the results will be published online in The Astrophysical Journal on Jan. 31.
Fermi has doubled the number of these rare events, called behind-the-limb flares, since it began scanning the sky in 2008. Its Large Area Telescope (LAT) has captured gamma rays with energies reaching 3 billion electron volts, some 30 times greater than the most energetic light previously associated with these “hidden” flares.
Thanks to NASA’s Solar Terrestrial Relations Observatory (STEREO) spacecraft, which were monitoring the solar far side when the eruptions occurred, the Fermi events mark the first time scientists have direct imaging of beyond-the-limb solar flares associated with high-energy gamma rays.
“Observations by Fermi’s LAT continue to have a significant impact on the solar physics community in their own right, but the addition of STEREO observations provides extremely valuable information of how they mesh with the big picture of solar activity,” said Melissa Pesce-Rollins, a researcher at the National Institute of Nuclear Physics in Pisa, Italy, and a co-author of the paper.
The hidden flares occurred Oct. 11, 2013, and Jan. 6 and Sept. 1, 2014. All three events were associated with fast coronal mass ejections (CMEs), where billion-ton clouds of solar plasma were launched into space. The CME from the most recent event was moving at nearly 5 million miles an hour as it left the sun. Researchers suspect particles accelerated at the leading edge of the CMEs were responsible for the gamma-ray emission.
Large magnetic field structures can connect the acceleration site with distant part of the solar surface. Because charged particles must remain attached to magnetic field lines, the research team thinks particles accelerated at the CME traveled to the sun’s visible side along magnetic field lines connecting both locations. As the particles impacted the surface, they generated gamma-ray emission through a variety of processes. One prominent mechanism is thought to be proton collisions that result in a particle called a pion, which quickly decays into gamma rays.
In its first eight years, Fermi has detected high-energy emission from more than 40 solar flares. More than half of these are ranked as moderate, or M class, events. In 2012, Fermi caught the highest-energy emission ever detected from the sun during a powerful X-class flare, from which the LAT detected highenergy gamma rays for more than 20 record-setting hours.
The dynamic space environment that surrounds Earth – the space our astronauts and spacecraft travel through – can be rattled by huge solar eruptions from the sun, which spew giant clouds of magnetic energy and plasma, a hot gas of electrically charged particles, out into space. The magnetic field of these solar eruptions are difficult to predict and can interact with Earth’s magnetic fields, causing space weather effects.
A new tool called EEGGL – short for the Eruptive Event Generator (Gibson and Low) and pronounced “eagle” – helps map out the paths of these magnetically structured clouds, called coronal mass ejections or CMEs, before they reach Earth. EEGGL is part of a much larger new model of the corona, the sun’s outer atmosphere, and interplanetary space, developed by a team at the University of Michigan. Built to simulate solar storms, EEGGL helps NASA study how a CME might travel through space to Earth and what magnetic configuration it will have when it arrives. The model is hosted by the Community Coordinated Modeling Center, or CCMC, at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
The new model is known as a “first principles” model because its calculations are based on the fundamental physics theory that describes the event – in this case, the plasma properties and magnetic free energy, or electromagnetics, guiding a CME’s movement through space.
Such computer models can help researchers better understand how the sun will affect near-Earth space, and potentially improve our ability to predict space weather, as is done by the U.S. National Oceanic and Atmospheric Administration.
Taking into account the magnetic structure of a CME from its initiation at the sun could mark a big step in CME modeling; various other models initiate CMEs solely based on the kinematic properties, that is, the mass and initial velocity inferred from spacecraft observations. Incorporating the magnetic properties at CME initiation may give scientists a better idea of a CME’s magnetic structure and ultimately, how this structure influences the CME’s path through space and interaction with Earth’s magnetic fields – an important piece to the puzzle of the sun’s dynamic behavior.
The model begins with real spacecraft observations of a CME, including the eruption’s initial speed and location on the sun, and then projects how the CME could travel based on the fundamental laws of electromagnetics. Ultimately, it returns a series of synthetic images, which look similar to those produced of actual observations from NASA and ESA’s SOHO or NASA’s STEREO, simulating the CME’s propagation through space.
A team led by Tamas Gombosi at the University of Michigan’s Department of Climate and Space Sciences and Engineering developed the model as part of its Space Weather Modeling Framework, which is also hosted at the CCMC. All of the CCMC’s space weather models are available for use and study by researchers and the public through runs on request. In addition, EEGGL, and the model it supports, is the first “first principles” model to simulate CMEs including their magnetic structure open to the public.
Originally published at NASA
Powerful solar storms can charge up the soil in frigid, permanently shadowed regions near the lunar poles, and may possibly produce “sparks” that could vaporize and melt the soil, perhaps as much as meteoroid impacts, according to NASA-funded research. This alteration may become evident when analyzing future samples from these regions that could hold the key to understanding the history of the moon and solar system.
As you watch the Moon over the course of a month, you’ll notice that different features are illuminated by the Sun at different times. However, there are some parts of the Moon that never see sunlight. These areas are called permanently shadowed regions, and they appear dark because unlike on the Earth, the axis of the Moon is nearly perpendicular to the direction of the sun’s light. The result is that the bottoms of certain craters are never pointed toward the Sun, with some remaining dark for over two billion years. However, thanks to new data from NASA’s Lunar Reconnaissance Orbiter, we can now see into these dark craters in incredible detail.
Credits: NASA Goddard/LRO mission
The moon has almost no atmosphere, so its surface is exposed to the harsh space environment. Impacts from small meteoroids constantly churn or “garden” the top layer of the dust and rock, called regolith, on the moon. “About 10 percent of this gardened layer has been melted or vaporized by meteoroid impacts,” said Andrew Jordan of the University of New Hampshire, Durham. “We found that in the moon’s permanently shadowed regions, sparks from solar storms could melt or vaporize a similar percentage.” Jordan is lead author of a paper on this research published online in Icarus August 31, 2016.
Explosive solar activity, like flares and coronal mass ejections, blasts highly energetic, electrically charged particles into space. Earth’s atmosphere shields us from most of this radiation, but on the moon, these particles — ions and electrons — slam directly into the surface. They accumulate in two layers beneath the surface; the bulky ions can’t penetrate deeply because they are more likely to hit atoms in the regolith, so they form a layer closer to the surface while the tiny electrons slip through and form a deeper layer. The ions have positive charge while the electrons carry negative charge. Since opposite charges attract, normally these charges flow towards each other and balance out.
In August 2014, however, Jordan’s team published simulation results predicting that strong solar storms would cause the regolith in the moon’s permanently shadowed regions (PSRs) to accumulate charge in these two layers until explosively released, like a miniature lightning strike. The PSRs are so frigid that regolith becomes an extremely poor conductor of electricity. Therefore, during intense solar storms, the regolith is expected to dissipate the build-up of charge too slowly to avoid the destructive effects of a sudden electric discharge, called dielectric breakdown. The research estimates the extent that this process can alter the regolith.
“This process isn’t completely new to space science — electrostatic discharges can occur in any poorly conducting (dielectric) material exposed to intense space radiation, and is actually the leading cause of spacecraft anomalies,” said Timothy Stubbs of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, a co-author of the paper. The team’s analysis was based on this experience. From spacecraft studies and analysis of samples from NASA’s Apollo lunar missions, the researchers knew how often large solar storms occur. From previous lunar research, they estimated that the top millimeter of regolith would be buried by meteoroid impacts after about a million years, so it would be too deep to be subject to electric charging during solar storms. Then they estimated the energy that would be deposited over a million years by both meteoroid impacts and dielectric breakdown driven by solar storms, and found that each process releases enough energy to alter the regolith by a similar amount.
“Lab experiments show that dielectric breakdown is an explosive process on a tiny scale,” said Jordan. “During breakdown, channels could be melted and vaporized through the grains of soil. Some of the grains may even be blown apart by the tiny explosion. The PSRs are important locations on the moon, because they contain clues to the moon’s history, such as the role that easily vaporized material like water has played. But to decipher that history, we need to know in what ways PSRs are not pristine; that is, how they have been weathered by the space environment, including solar storms and meteoroid impacts.”
The next step is to search for evidence of dielectric breakdown in PSRs and determine if it could happen in other areas on the moon. Observations from NASA’s Lunar Reconnaissance Orbiter spacecraft indicate that the soil in PSRs is more porous or “fluffy” than other areas, which might be expected if breakdown was blasting apart some of the soil grains there. However, experiments, some already underway, are needed to confirm that breakdown is responsible for this. Also, the lunar night is long — about two weeks — so it can become cold enough for breakdown to occur in other areas on the moon, according to the team. There may even be “sparked” material in the Apollo samples, but the difficulty would be determining if this material was altered by breakdown or a meteoroid impact. The team is working with scientists at the Johns Hopkins University Applied Physics Laboratory on experiments to see how breakdown affects the regolith and to look for any tell-tale signatures that could distinguish it from the effects of meteoroid impacts.
NASA funded the research through the Lunar Reconnaissance Orbiter (LRO) mission and the Solar System Exploration Research Virtual Institute (SSERVI) Dynamic Response of the Environments at Asteroids, the Moon, and Mars 2 (DREAM2) center at NASA Goddard. SSERVI is headquartered out of NASA’s Ames Research Center, Moffett Field, California. LRO is managed by NASA Goddard as a project under NASA’s Discovery Program. The Discovery Program is managed by NASA’s Marshall Spaceflight Center in Huntsville, Alabama, for the Science Mission Directorate at NASA Headquarters in Washington.
On April 17, 2016, an active region on the sun’s right side released a mid-level solar flare, captured here by NASA’s Solar Dynamics Observatory. This solar flare caused moderate radio blackouts, according to NOAA’s Space Weather Prediction Center. Scientists study active regions – which are areas of intense magnetism – to better understand why they sometimes erupt with such flares. This video was captured in several wavelengths of extreme ultraviolet light, a type of light that is typically invisible to our eyes, but is color-coded in SDO images for easy viewing.
Credit: Goddard Media