heliosphere!

Eclipse 2017 From Space

On Aug. 21, 2017, a total solar eclipse passed over North America. People throughout the continent captured incredible images of this celestial phenomenon. We and our partner agencies had a unique vantage point on the eclipse from space. Here are a few highlights from our fleet of satellites that observe the Sun, the Moon and Earth.

Our Solar Dynamics Observatory, or SDO, which watches the Sun nearly 24/7 from its orbit 3,000 miles above Earth, saw a partial eclipse on Aug. 21.

SDO sees the Moon cross in front of the Sun several times a year. However, these lunar transits don’t usually correspond to an eclipse here on Earth, and an eclipse on the ground doesn’t guarantee that SDO will see anything out of the ordinary. In this case, on Aug. 21, SDO did see the Moon briefly pass in front of the Sun at the same time that the Moon’s shadow passed over the eastern United States. From its view in space, SDO only saw 14 percent of the Sun blocked by the Moon, while most U.S. residents saw 60 percent blockage or more.

Six people saw the eclipse from the International Space Station. Viewing the eclipse from orbit were NASA’s Randy Bresnik, Jack Fischer and Peggy Whitson, the European Space Agency’s Paolo Nespoli, and Roscosmos’ Commander Fyodor Yurchikhin and Sergey Ryazanskiy. The space station crossed the path of the eclipse three times as it orbited above the continental United States at an altitude of 250 miles.

From a million miles out in space, our Earth Polychromatic Imaging Camera, or EPIC, instrument captured 12 natural color images of the Moon’s shadow crossing over North America. EPIC is aboard NOAA’s Deep Space Climate Observatory, or DSCOVR, where it photographs the full sunlit side of Earth every day, giving it a unique view of the shadow from total solar eclipses. EPIC normally takes about 20 to 22 images of Earth per day, so this animation appears to speed up the progression of the eclipse.

A ground-based image of the total solar eclipse – which looks like a gray ring – is superimposed over a red-toned image of the Sun’s atmosphere, called the corona. This view of the corona was captured by the European Space Agency and our Solar and Heliospheric Observatory, or SOHO. At center is an orange-toned image of the Sun’s surface as seen by our Solar Dynamics Observatory in extreme ultraviolet wavelengths of light.

During a total solar eclipse, ground-based telescopes can observe the lowest part of the solar corona in a way that can’t be done at any other time, as the Sun’s dim corona is normally obscured by the Sun’s bright light. The structure in the ground-based corona image — defined by giant magnetic fields sweeping out from the Sun’s surface — can clearly be seen extending into the outer image from the space-based telescope. The more scientists understand about the lower corona, the more they can understand what causes the constant outward stream of material called the solar wind, as well as occasional giant eruptions called coronal mass ejections.

As millions of Americans watched the total solar eclipse that crossed the continental United States, the international Hinode solar observation satellite captured its own images of the awe-inspiring natural phenomenon. The images were taken with Hinode’s X-ray telescope, or XRT, as it flew above the Pacific Ocean, off the west coast of the United States, at an altitude of approximately 422 miles. Hinode is a joint endeavor by the Japan Aerospace Exploration Agency, the National Astronomical Observatory of Japan, the European Space Agency, the United Kingdom Space Agency and NASA.

During the total solar eclipse our Lunar Reconnaissance Orbiter, or LRO, in orbit around the Moon, turned one of its instruments towards Earth to capture an image of the Moon’s shadow over a large region of the United States.

As LRO crossed the lunar south pole heading north at 3,579 mph, the shadow of the Moon was racing across the United States at 1,500 mph. A few minutes later, LRO began a slow 180-degree turn to look back at Earth, capturing an image of the eclipse very near the location where totality lasted the longest. The spacecraft’s Narrow Angle Camera began scanning Earth at 2:25:30 p.m. EDT and completed the image 18 seconds later.

Sensors on the polar-orbiting Terra and Suomi NPP satellites gathered data and imagery in swaths thousands of miles wide. The Moderate Resolution Imaging Spectroradiometer, or MODIS, sensor on Terra and Visible Infrared Imaging Radiometer Suite, or VIIRS, on Suomi NPP captured the data used to make this animation that alternates between two mosaics. Each mosaic is made with data from different overpasses that was collected at different times.

This full-disk geocolor image from NOAA/NASA’s GOES-16 shows the shadow of the Moon covering a large portion of the northwestern U.S. during the eclipse.

Our Interface Region Imaging Spectrograph, or IRIS, mission captured this view of the Moon passing in front of the Sun on Aug. 21.  

Check out nasa.gov/eclipse to learn more about the Aug. 21, 2017, eclipse along with future eclipses, and follow us on Twitter for more satellite images like these: @NASASun, @NASAMoon, and @NASAEarth.

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

TOPSY-TURVY MOTION CREATES LIGHT SWITCH EFFECT AT URANUS:
UNLIKE EARTH, THIS ICY PLANET’S MAGNETOSPHERE OPENS & CLOSES EVERY DAY

More than 30 years after Voyager 2 sped past Uranus, Georgia Institute of Technology researchers are using the spacecraft’s data to learn more about the icy planet. Their new study suggests that Uranus’ magnetosphere, the region defined by the planet’s magnetic field and the material trapped inside it, gets flipped on and off like a light switch every day as it rotates along with the planet. It’s “open” in one orientation, allowing solar wind to flow into the magnetosphere; it later closes, forming a shield against the solar wind and deflecting it away from the planet.

This is much different from Earth’s magnetosphere, which typically only switches between open and closed in response to changes in the solar wind. Earth’s magnetic field is nearly aligned with its spin axis, causing the entire magnetosphere to spin like a top along with the Earth’s rotation. Since the same alignment of Earth’s magnetosphere is always facing toward the Sun, the magnetic field threaded in the ever-present solar wind must change direction in order to reconfigure Earth’s field from closed to open. This frequently occurs with strong solar storms.

But Uranus lies and rotates on its side, and its magnetic field is lopsided – it’s off-centered and tilted 60 degrees from its axis. Those features cause the magnetic field to tumble asymmetrically relative to the solar wind direction as the icy giant completes its 17.24-hour full rotation.

Rather than the solar wind dictating a switch like here on Earth, the researchers say Uranus’ rapid rotational change in field strength and orientation lead to a periodic open-close-open-close scenario as it tumbles through the solar wind.

“Uranus is a geometric nightmare,” said Carol Paty, the Georgia Tech associate professor who co-authored the study. “The magnetic field tumbles very fast, like a child cartwheeling down a hill head over heels. When the magnetized solar wind meets this tumbling field in the right way, it can reconnect and Uranus’ magnetosphere goes from open to closed to open on a daily basis.”

Paty says this solar wind reconnection is predicted to occur upstream of Uranus’ magnetosphere over a range of latitudes, with magnetic flux closing in various parts of the planet’s twisted magnetotail.

Reconnection of magnetic fields is a phenomenon throughout the solar system. It occurs when the direction of the interplanetary magnetic field – which comes from the Sun and is also known as the heliospheric magnetic field – is opposite a planet’s magnetospheric alignment. Magnetic field lines are then spliced together and rearrange the local magnetic topology, allowing a surge of solar energy to enter the system.

Magnetic reconnection is one reason for Earth’s auroras. Auroras could be possible at a range of latitudes on Uranus due to its off-kilter magnetic field, but the aurora is difficult to observe because the planet is nearly 2 billion miles from Earth. The Hubble Space Telescope occasionally gets a faint view, but it can’t directly measure Uranus’ magnetosphere.

The Georgia Tech researchers used numerical models to simulate the planet’s global magnetosphere and to predict favorable reconnection locations. They plugged in data collected by Voyager 2 during its five-day flyby in 1986. It’s the only time a spacecraft has visited.

The researchers say learning more about Uranus is one key to discovering more about planets beyond our solar system.

“The majority of exoplanets that have been discovered appear to also be ice giants in size,” said Xin Cao, the Georgia Tech Ph.D. candidate in Earth and atmospheric sciences who led the study. “Perhaps what we see on Uranus and Neptune is the norm for planets: very unique magnetospheres and less-aligned magnetic fields. Understanding how these complex magnetospheres shield exoplanets from stellar radiation is of key importance for studying the habitability of these newly discovered worlds.”

Voyager: The Space Between

Our Voyager 1 spacecraft officially became the first human-made object to venture into interstellar space in 2012. 

Whether and when our Voyager 1 spacecraft broke through to interstellar space, the space between stars, has been a thorny issue. 

In 2012, claims surfaced every few months that Voyager 1 had “left our solar system.” Why had the Voyager team held off from saying the craft reached interstellar space until 2013?

Basically, the team needed more data on plasma, which is an ionozied gas that exists throughout space. (The glob of neon in a storefront sign is an example of plasma).

Plasma is the most important marker that distinguishes whether Voyager 1 is inside the solar bubble, known as the heliosphere.  The heliosphere is defined by the constant stream of plasma that flows outward from our Sun – until it meets the boundary of interstellar space, which contains plasma from other sources.

Adding to the challenge: they didn’t know how they’d be able to detect it.

No one has been to interstellar space before, so it’s  like traveling with guidebooks that are incomplete.

Additionally, Voyager 1’s plasma instrument, which measures the density, temperature and speed of plasma, stopped working in 1980, right after its last planetary flyby.

When Voyager 1 detected the pressure of interstellar space on our heliosphere in 2004, the science team didn’t have the instrument that would provide the most direct measurements of plasma. 

Voyager 1 Trajectory

Instead, they focused on the direction of the magnetic field as a proxy for source of the plasma. Since solar plasma carries the magnetic field lines emanating from the Sun and interstellar plasma carries interstellar magnetic field lines, the directions of the solar and interstellar magnetic fields were expected to differ.

Voyager 2 Trajectory

In May 2012, the number of galactic cosmic rays made its first significant jump, while some of the inside particles made their first significant dip. The pace of change quickened dramatically on July 28, 2012. After five days, the intensities returned to what they had been. This was the first taste test of a new region, and at the time Voyager scientists thought the spacecraft might have briefly touched the edge of interstellar space.

By Aug. 25, when, as we now know, Voyager 1 entered this new region for good, all the lower-energy particles from inside zipped away. Some inside particles dropped by more than a factor of 1,000 compared to 2004. However, subsequent analysis of the magnetic field data revealed that even though the magnetic field strength jumped by 60% at the boundary, the direction changed less than 2 degrees. This suggested that Voyager 1 had not left the solar magnetic field and had only entered a new region, still inside our solar bubble, that had been depleted of inside particles.

Then, in April 2013, scientists got another piece of the puzzle by chance. For the first eight years of exploring the heliosheath, which is the outer layer of the heliosphere, Voyager’s plasma wave instrument had heard nothing. But the plasma wave science team had observed bursts of radio waves in 1983 and 1984 and again in 1992 and 1993. They determined these bursts were produced by the interstellar plasma when a large outburst of solar material would plow into it and cause it to oscillate.

It took about 400 days for such solar outbursts to reach interstellar space, leading to an estimated distance of 117 to 177 AU (117 to 177 times the distance from the Sun to the Earth) to the heliopause.

Then on April 9, 2013, it happened: Voyager 1’s plasma wave instrument picked up local plasma oscillations. Scientists think they probably stemmed from a burst of solar activity from a year before. The oscillations increased in pitch through May 22 and indicated that Voyager was moving into an increasingly dense region of plasma.

The above soundtrack reproduces the amplitude and frequency of the plasma waves as “heard” by Voyager 1. The waves detected by the instrument antennas can be simply amplified and played through a speaker. These frequencies are within the range heard by human ears.

When they extrapolated back, they deduced that Voyager had first encountered this dense interstellar plasma in Aug. 2012, consistent with the sharp boundaries in the charged particle and magnetic field data on Aug. 25.

In the end, there was general agreement that Voyager 1 was indeed outside in interstellar space, but that location comes with some disclaimers. They determined the spacecraft is in a mixed transitional region of interstellar space. We don’t know when it will reach interstellar space free from the influence of our solar bubble.

Voyager 1, which is working with a finite power supply, has enough electrical power to keep operating the fields and particles science instruments through at least 2020, which will make 43 years of continual operation.

Voyager 1 will continue sending engineering data for a few more years after the last science instrument is turned off, but after that it will be sailing on as a silent ambassador. 

In about 40,000 years, it will be closer to the star AC +79 3888 than our own Sun.

And for the rest of time, Voyager 1 will continue orbiting around the heart of the Milky Way galaxy, with our Sun but a tiny point of light among many.

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

A Fresh Bouquet Ch17 Preview

“You can come over and say hi,” Poppy murmurs, refusing to tear her eyes away from the tiny little being that is now the centre of her heliosphere, the very core of what her entire life will now revolve around. 

She doesn’t know how Regulus will really respond to Sol; it’s not like they’d gotten much chance to discuss him while they were downstairs. And like hell is she spending her baby’s precious few hours awake to talk to Regulus. She might be open to the concept of a relationship (whatever kind of relationship that ends up being, well, they will see), but he comes second to Sol. 

“It’s not like he will be able to comprehend what I’m saying to him,” Regulus objects, even as he moves closer, just until he’s standing right beside her. 

“Not right now, but he’ll hear your voice and come to familiarise himself with it… you are planning on-” 

“Of course I’m planning on sticking around,” Regulus snaps and the glare he sends her is glacial.

This composite image shows a coronal mass ejection, a type of space weather linked to solar energetic particles, as seen from two space-based solar observatories and one ground-based instrument. The image in gold is from NASA’s Solar Dynamics Observatory, the image in blue is from the Manua Loa Solar Observatory’s K-Cor coronagraph, and the image in red is from ESA and NASA’s Solar and Heliospheric Observatory.

Our constantly-changing sun sometimes erupts with bursts of light, solar material, or ultra-fast energized particles — collectively, these events contribute to space weather. A new study shows that the warning signs of one type of space weather event can be detected tens of minutes earlier than with current forecasting techniques – critical extra time that could help protect astronauts in space. 

Credits: NASA/ESA/SOHO/SDO/Joy Ng and MLSO/K-Cor

Magnetosphere of Jupiter

The magnetosphere of Jupiter is the cavity created in the solar wind by the planet’s magnetic field. Extending up to seven million kilometers in the Sun’s direction and almost to the orbit of Saturn in the opposite direction, Jupiter’s magnetosphere is the largest and most powerful of any planetary magnetosphere in the Solar System, and by volume the largest known continuous structure in the Solar System after the heliosphere. Wider and flatter than the Earth’s magnetosphere, Jupiter’s is stronger by an order of magnitude, while its magnetic moment is roughly 18,000 times larger. The existence of Jupiter’s magnetic field was first inferred from observations of radio emissions at the end of the 1950s and was directly observed by the Pioneer 10 spacecraft in 1973.

Image Credit: NASA/JPL

2

The Voyager Golden Records are phonograph records that were included aboard both Voyager spacecraft launched in 1977.  The records contain sounds and images selected to portray the diversity of life and culture on Earth, and are intended for any intelligent extraterrestrial life form, or for future humans, who may find them.

Photos: NASA

—-

It was 40 years ago, on Aug. 20 and Sept. 5, 1977, that a pair of robots named Voyager were dispatched to explore the outer solar system and the vast darkness beyond.

The Voyager 1 probe is currently the farthest human made object from Earth. Voyager 1 has reached interstellar space, the region between stars where the galactic plasma is present.

Voyager 2 is currently in the “Heliosheath” – the outermost layer of the heliosphere where the solar wind is slowed by the pressure of interstellar gas.

5

Solar spectacular seen from Earth and space

While ground-based observers experienced the awe-inspiring view of a total solar eclipse yesterday, astronauts aboard the International Space Station, and our Sun-watching satellites, enjoyed unique perspectives of this spectacular sight from space.

Thanks to a quirk of our cosmos, the Moon’s average distance from Earth is just right for it to appear as the same size in the sky as the significantly larger Sun: the Sun’s diameter is 400 times wider than the Moon’s, but it is also 400 times farther away.


When the two align such that the Moon slides directly between Earth and the Sun, it appears to cover our star completely, temporarily blocking out its light and creating a total solar eclipse for those along the narrow path cast by the Moon’s shadow.

Yesterday, 21 August, observers situated along a 115 km-wide swath stretching from Oregon to South Carolina in the US were under this path of totality. The eclipse shadow took about 1.5 hours to cross the continent, with the peak totality lasting for about 2 minutes 40 seconds.

A team of astronomers from ESA imaged the eclipse from the US and captured phenomena such as beads of light shining through gaps in the lunar terrain, and the glittering ‘diamond ring’ effect as the last and first slither of sunlight glints through immediately before and after totality.

They also imaged the Sun’s extended atmosphere, the corona, which is visible to the naked eye only during totality when the rest of the Sun’s light is blocked out.

Astronomers at ESA’s Spaceport in Kourou, French Guiana, enjoyed a partial eclipse after totality had finished in North America. On the north-eastern coast of South America, it was one of the last places to observe the eclipse before it ended worldwide.

Lucky observers in the westernmost parts of Europe also captured a few moments of the partial eclipse at sunset, including astronomers observing from ESA’s European Space Astronomy Centre near Madrid, in Spain.


Meanwhile, from their unique vantage point about 400 km above Earth, astronauts aboard the International Space Station, including ESA’s Paolo Nespoli, viewed partial eclipses and the Moon’s fuzzy shadow on the surface of the planet. The space station traversed across the path of totality three times on its 90 minute-long orbits around the Earth.


Also orbiting Earth 14.5 times a day in its 800 km altitude polar orbit is ESA’s Proba-2 satellite, which was predicted to see the Moon pass four times through its field-of-view, with three partial eclipses.

Further away, some 1.5 million kilometres from Earth towards the Sun, the ESA/NASA Solar and Heliospheric Observatory, SOHO, captured views of the Sun’s activity and extended coma.

For SOHO, eclipses are business as usual: it permanently blocks out the light from the Sun’s disc in order to see fine details in the corona and features in the Sun’s extended atmosphere.


These space-based images provide useful context for the ground-based astronomers, offering wide views of the corona and the Sun’s activity at the time of the eclipse, and at a range of wavelengths. This helps to link the features seen at a range of scales, giving an insight into the Sun’s dynamic activity.


TOP IMAGE….The total solar eclipse seen from Casper, Wyoming (US), by a team of ESA astronomers. The image shows the moment of totality, when the Moon passed directly in front of the Sun, blocking its light and revealing the details of the Sun’s atmosphere, its corona. Copyright ESA/M.P. Ayucar, CC BY-SA 3.0 IGO

UPPER IMAGE….Astronomers observing from ESA’s Spaceport in Kourou enjoyed views of the partial eclipse yesterday. The image here was taken during the maximum extent of the partial eclipse. Sunspots are also visible on the solar disc. Copyright Cédric Laffay (2017)

CENTRE INMAGE….ESA astronaut Paolo Nespoli took this picture during the total solar eclipse of the Sun over the US on 21 August 2017.
From their unique vantage point 400 km above Earth’s surface, astronauts aboard the International Space Station saw the Moon’s fuzzy shadow on the surface of our planet during the eclipse. The space station crossed the path of the eclipse three times on its 90 minute-long orbits around the Earth. Copyright ESA/NASA

LOWER IMAGE….As the US enjoyed a total solar eclipse on 21 August 2017, ESA’s Sun-watching Proba-2 satellite captured partial eclipses from its viewpoint, 800 km above Earth. Proba-2 orbits Earth about 14.5 times per day, and thanks to the constant change in viewing angle, it can dip in and out of the Moon’s shadow several times during a solar eclipse. This still image shows one of the first images available from today’s eclipse, taken at 17:08 GMT. The image was taken by the SWAP imager, and shows the solar disc in extreme-ultraviolet light to capture its turbulent surface and swirling corona corresponding to temperatures of about a million degrees. Copyright ESA/Royal Observatory Belgium

BOTTOM IMAGE….This composite image of the Sun and its corona was taken by the ESA/NASA SOHO satellite and ESA’s Proba-2 satellite yesterday, during the time of Earth’s total solar eclipse. The central image shows an extreme-ultraviolet image of the solar disc taken by Proba-2 at 18:55 GMT, while the corona and extended atmospheric features are seen by SOHO in the red image from 2–6 solar radii, and beyond in blue (SOHO can see up to about 32 solar radii) at 18:48 and 19:06 GMT, respectively. The black circular region corresponds to an occulting mask to cut out direct sunlight that would otherwise obscure the details close to the Sun – similar to the effect of the Moon in a total solar eclipse. As such, these images provide important context for images captured during the eclipse by ground-based astronomers.
The image was composed using JHelioviewer. Copyright SOHO (ESA & NASA); Proba-2: ESA/Royal Observatory of Belgium

NASA's Cassini, Voyager missions suggest new picture of Sun's interaction with galaxy

New data from NASA’s Cassini mission, combined with measurements from the two Voyager spacecraft and NASA’s Interstellar Boundary Explorer, or IBEX, suggests that our sun and planets are surrounded by a giant, rounded system of magnetic field from the sun – calling into question the alternate view of the solar magnetic fields trailing behind the sun in the shape of a long comet tail.

The sun releases a constant outflow of magnetic solar material – called the solar wind – that fills the inner solar system, reaching far past the orbit of Neptune. This solar wind creates a bubble, some 23 billion miles across, called the heliosphere. Our entire solar system, including the heliosphere, moves through interstellar space. The prevalent picture of the heliosphere was one of comet-shaped structure, with a rounded head and an extended tail. But new data covering an entire 11-year solar activity cycle show that may not be the case: the heliosphere may be rounded on both ends, making its shape almost spherical. A paper on these results was published in Nature Astronomy on April 24, 2017.

Keep reading

youtube

Where is the Edge of the Solar System? 

Where does the solar system end?

It all depends on the criteria you are using.

Based on where the planets end, you could say it’s Neptune and the Kuiper Belt. If you measure by edge of the sun’s magnetic fields, the end is the heliosphere. If you judge by the stopping point of sun’s gravitational influence, the solar system would end at the Oort Cloud.

Credit: NASA’s Goddard Space Flight Center/Genna Duberstein

With its C2 coronagraph instrument, SOHO captured a blossoming coronal mass ejection as it roared into space from the right side of the Sun (Dec. 28, 2013). SOHO also produces running difference images and movies of the Sun’s corona in which the difference between one image and the next (taken about 10 minutes apart) is highlighted.

This technique strongly emphasizes the changes that occurred. Here we have taken a single white light frame and shift it back and forth with a running difference image taken at the same time to illustrate the effect.

Credit: SOHO (ESA & NASA)

anonymous asked:

If space colonies were built at the Lagrange Points, would life be able to survive?

Short answer: yes.

Long answer: Lagrange Points are totally awesome places to hang out!

What’s a Lagrange Point you might ask? A Lagrange Point is an area between two orbiting bodies where the gravitational pull between the bodies are balanced along with the centripetal forces of the objects in orbit.

In other words, they’re places between two orbiting bodies where a satellite will maintain a stable relation with the other two bodies.

Here’s a diagram showing the five Lagrange Points between Earth and the Sun. Any two orbiting bodies will have these same five Lagrange Points between them.

L1, L2, and L3 are all in a line intersecting the center of mass of the two bodies. They are also the least stable off the five points. Satellites parked in these three places have a tendency to wander off after a while and require the occasional rocket burn to stay.

We actually have a couple of space probes at our L1 point with the Sun. Because L1 gets an totally uninterrupted view of the sun, NASA put their Solar and Heliospheric Observatory and NOAA’s Deep Space Climate Observatory there. Our solar L2 is currently occupied by NASA’s Wilkinson Microwave Anisotropy Probe which is measuring the cosmic background radiation left over from the Big Bang. This is also where the James Webb Space Telescope will be placed in 2018. 

L4 and L5 are 60 degrees ahead and behind the Earth and are much more stable. L4 precedes it’s planet in orbit, while L5 trails. Satellites there will kinda drift around a bit but stay in the general area.

Because L4 and L5 are stable, cosmic dust and debris tend to gather and stay there. Asteroids that hang out at a planet’s L4 or L5 points are called Trojans by astronomers. Jupiter has a number of Trojans in it’s L4 and L5 points. And by ‘a number’, I mean a cosmic truckload.


Even Earth has at least one trojan in it’s L4 point. There’s probably a few more, we just haven’t seen them yet.

Asteroids are classified into three broad types - C, S, and X. Each type has a number of subtypes, but in general C-types are carbonaceous and include asteroids with a lots of ices, S-types are primarily stone or rock, while X-types include asteroids with high amounts of metals and other stuff.

So, not only are the L4 and L5 points stable places for your space colony, they’re also a good source of asteroids to mine for the metals you need to build the colony and the and ices (for water and other gasses) you need to survive.

Closer to home, there are also five Lagrange points between the Earth and our Moon.



These L4 and L5 points with our Moon are also very stable places to put your closer-to-Earth space colonies.

Edit: I attached the wrong graphic for the Earth-Moon Lagrange points. I fixed it.

The Solar and Heliospheric Observatory (SOHO) has been watching the Sun for almost 20 years. In that time it has seen solar activity ramp up and die down repeatedly. Its Extreme ultraviolet Imaging Telescope has taken images of the resulting waxing and waning of the Sun’s corona – its atmosphere – that are impossible to record from the ground.

Brighter images show times when there was more activity on the Sun. This activity is driven by the Sun’s magnetic field and follows a cycle of about 11 years. 

credit: SOHO (ESA&NASA)

20 Years of the Solar and Heliospheric Observatory

The Solar and Heliospheric Observatory, SOHO for short, has captured the imagination of scientists and the public alike for two decades now. We teamed up with the European Space Agency (ESA) on SOHO, which observes the sun from space. It was launched 20 years ago this week, on Dec. 2, 1995, with the mission to study the internal structure of our neighborhood star, its atmosphere and the origin of the solar wind. SOHO sends spectacular data daily, and has led scientists to a wealth of understanding.

Here are the top 5 things you need to know about SOHO, the sun and other solar observation missions:

1. SOHO Set Out for Space with an Ambitious Mission

SOHO was designed to answer three fundamental scientific questions about the sun: What are the structure and dynamics of the solar interior? Why does the solar corona exist and how is it heated to such an extremely high temperature? Where is the solar wind produced and how is it accelerated? Clues about the solar interior come from studying seismic waves that appear as ripples on the sun’s surface, a technique called helioseismology.

2. SOHO Enjoys a Great View

SOHO commands an uninterrupted view of the sun, while always staying within easy communication range of controllers at home. The space-based observatory moves around the sun in step with the Earth, by slowly orbiting around a unique point in space called the First Lagrangian Point (L1). There, the combined gravity of the Earth and sun keep SOHO in a position that’s always between the sun and the Earth. The L1 point is about 1 million miles (about 1.5 million kilometers) away from Earth (about four times the distance to the Moon).

3. Bonus Discoveries: Lots of Comets

Besides watching the sun, SOHO has become the most prolific discoverer of comets in astronomical history. In September 2015, SOHO found its 3000th comet. Sometimes the spacecraft’s instruments capture comets plunging to their death as they collide with the sun.

4. Extra Innings

SOHO was meant to operate until 1998, but it was so successful that ESA and NASA decided to prolong its life several times and endorsed several mission extensions. Because of this, the mission has been able to observe an entire 11-year solar cycle and much of the next.

5. Keep Your Eye (Safely) on the Sun

You can see what SOHO sees, almost in real time. The latest images from the spacecraft, updated several times daily, are available online. Take a look HERE

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