Could Cassini See You On “The Day The Earth Smiled?”

The face of Earth aimed toward Cassini during imaging on July 19, 2013

So along with the rest of the world, you smiled. You waved. You went outside on July 19, wherever you were, and looked upwards and out into the solar system knowing that our robotic representative Cassini would be capturing a few pixels’ worth of photons bouncing off our planet when they eventually reached Saturn, 900 million miles away. But did Cassini actually capture any photons coming from where you were? The image above will tell you.

Assembled by the Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo (where the enormous 305-meter radio telescope is located) this image shows what side of Earth was facing Cassini when its “pale blue dot” images were obtained, at approximately 22:47 UTC (Cassini time.)

Didn’t make it into Cassini’s photo? That’s ok… maybe MESSENGER had already caught you earlier that very same day:

The view of Earth seen by MESSENGER from Mercury on July 19, 2013
The view of Earth seen by MESSENGER from Mercury on July 19, 2013

Before Cassini took its images — several hours before, in fact — the MESSENGER spacecraft was holding some photo shoots of its own from 61 million miles in the other direction!

The image above shows the side of Earth that was facing Mercury on the morning of July 19, 2013, when MESSENGER was acquiring images in our direction during a hunt for any possible satellites of the innermost planet.

Earth was as bright (-4.8 magnitude) as the maximum brightness of Venus at the moment the image was taken from Mercury.

Of course, in both series of images specific details of our planet can’t be made out — Earth was barely more than a pixel in size (regardless of any bloom caused by apparent brightness.) Clouds, countries, continents, oceans… the entire population of our world, reduced to a single point of light — a “mote of dust suspended in a sunbeam.”

For both portrayals, high-resolution black and white images from the GOES East and Meteosat meteorological satellites were combined with color information from NASA Visible Earth to generate true-color images of our planet as it would have looked to each respective imaging spacecraft… if they had the impossibly-precise optics to resolve Earth from such distances, of course.

But it’s ok that they don’t… we can still use our imaginations.

Read more here on the PHL’s news release.

Earth from the geostationary weather satellite GOES East on July 19, 2013 at 5 PM EST. This is approximately the view that Cassini would have had of Earth during imaging.
Earth from the geostationary weather satellite GOES East on July 19, 2013 at 5 PM EST. This is approximately the view that Cassini would have had of Earth during imaging.

Image credits: PHL @ UPR Arecibo, NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington, NERC Satellite Station, Dundee University, Scotland. Thanks to Prof. Abel Méndez (PHL/UCR) for the heads-up on these.

What Can You Do With a Cubesat?

Three small CubeSats are deployed from the International Space Station on October 4, 2012. Credit: NASA

We’ve had several articles recently cubesats — low-cost satellites that seem to be the wave of the future. As technology becomes miniaturized, this allows for inexpensive and quick-to-build satellites. Additionally, they can tag along on launches already scheduled for other things. All this enables students and smaller companies to send equipment and experiments into space.

But the people from DIY Space Exploration say don’t let the small size of a cubesat fool you. The types of missions Cubesats can perform may surprise you and they’re becoming the satellite of choice for anyone looking for a low cost quick response option.

If you visit the DIY Space Exploration website, they have tutorials on how you can put your own cubesat together, and lots of other information. They’ve also put together a great infograhic about what all you can do with a cubesat:

Why are We Driven to Explore?

Why do we explore? Is it the desire to break through boundaries, or to probe the perimeters of possibilities? With his lightning-fast mind, self-professed wonder junkie Jason Silva can quickly list all the great quotes about space exploration and why it is important for the human species to explore; and he does it in this new video from his “Shots of Awe” series on You Tube.

Strap in and enjoy the fast ride that is Jason Silva!
Continue reading “Why are We Driven to Explore?”

Space Debris: A Tale of Two Satellites

Artist's concept of a GOES spacecraft in orbit. (Credit: NOAA.gov).

It’s sometimes tough being a satellite in Earth orbit these days.

An interesting commentary came our way recently via NASA’s Orbital Debris Program Office’s Orbital Debris Quarterly News. The article, entitled High-Speed Particle Impacts Suspected in Two Spacecraft Anomalies, highlights a growing trend in the local space environment.

The tale begins with GOES 13 located in geostationary orbit over longitude 75° West. Launched on May 24th, 2006 atop a Delta IV rocket, GOES 13 is an integral part of the U.S. National Oceanic and Atmospheric Administration (NOAA’s) Geostationary Operational Environmental Satellite network.

The problems began when GOES-13 began to suffer an “attitude disturbance of unknown origin” on May 22nd of this year, causing it to drift about two degrees per hour off of its required nadir (the opposite of zenith) pointing.

The anomaly was similar to a problem encountered by the NOAA 17 spacecraft on November 20th, 2005. At the time, the anomaly was suspected to be due to a micrometeoroid impact. The Leonid meteors, which peak right around the middle of November, were a chief suspect. However, NOAA 17 suffered a second failure 18 days later, which was later traced down to a hydrazine leak from its errant thrusters.

GOES-13 has weathered hard times before.  Back in December of 2006, GOES-13’s Solar X-Ray Imager suffered damage after being struck by a solar flare shortly after initial deployment.   GOES-13 also began returning degraded imagery in September 2012, forcing it into backup status for Hurricane Sandy.

GOES-13 was restored to functionality last month. Current thinking is that the satellite was struck by a micrometeorite. No major meteor showers were active at the time.

Loss of a GOES satellite would place a definite strain on our weather monitoring and Earth observing capability. Begun with the launch of GOES-1 in 1975, currently six GOES satellites are in operation, including one used to relay data for PeaceSat (GOES-7) and one used as a communications relay for the South Pole research station (GOES-3).

The GOES program cost NOAA billions in cost overruns to execute. The next GOES launch is GOES-R scheduled in 2015.

But the universe seems to love coincidences.

NEE-01 Pegaso before deployment. (Credit:
NEE-01 Pegaso before deployment. (Credit: Wikimedia Commons image in the Public Domain).

Less than 26 hours after the GOES 13 anomaly, Ecuador’s first satellite, NEE-01 Pegaso began to have difficulties keeping a stable attitude. The event happened shortly after passage near an old Soviet rocket booster (NORAD designation 1986-058B) which launched Kosmos 1768 on August 2nd, 1986. The U.S. Joint Space Operations Center had warned the fledgling Ecuadorian Space Agency that conjunction was imminent, but of course, there’s not much that could’ve been done to save the tiny CubeSat.

Although the main mass passed Pegaso at a safe distance, current thinking is that the discarded booster may have left a cloud of debris in its wake. Researchers have tracked small “debris clouds” around objects it orbit before- the collision of Iridium 33 and the defunct Kosmos 2251 on February 10th, 2009 left a ring of debris in its wake, and the Chinese anti-satellite test carried out on January 11th, 2007 showered low-Earth orbit with debris for years to come.

The loss represents a blow to Ecuador and their first bid to become a space-faring nation. Launched less than a month prior atop a Long March 2D rocket, Pegaso was a small 10 centimetre nanosatellite equipped with solar panels and dual infrared and visible Earth imaging systems.

A translation from the Ecuadorian Space Agencies site states that;

 “The NEE-01 survived the crash and remains in orbit; however it has entered uncontrolled rotation due to the event.

 Due to this rotation, (the satellite) cannot point its antenna correctly and stably to the Earth station and although still transmitting and running, the signal cannot be decoded. The Ecuadorian Civilian Space Agency is working tirelessly to stabilize the NEE-01 and recover the use of their signal.

The PEGASUS aired for 7 days your signal to the world via EarthCam, millions could see the Earth seen from space in real time, many for the first time, the files in those 7 days have been published after transmission.”

Ecuador plans to launch another CubeSat, NEE 02 Krysaor later in 2013. A carrier has not yet been named.

While both events suffered by the GOES-13 and NEE-01 Pegaso satellites were unrelated, they underscore problems with space junk and space environmental hazards that are occurring with a higher frequency.

Gabbard diagram displaying a sample disintegration of a Long March 4 booster in 2000. (Credit: the NASA Orbital Debris Office).
Gabbard diagram displaying a sample disintegration of a Long March 4 booster in 2000. (Credit: the NASA Orbital Debris Office).

Such is the modern hazardous environment of low Earth orbit that new satellites must face. With a growing amount of debris, impact threats are becoming more common. The International Space Station must perform frequent debris avoidance maneuvers to avoid hazards, and more than once, the crew has waited out a pass in their Soyuz escape modules should immediate evacuation become necessary.  Punctures from micro-meteoroids or space junk have even been seen recently on the ISS solar panel arrays.

Plans are on the drawing board to deal with space junk, involving everything from “space nets” to lasers and even more exotic ideas. Probably the most immediate solution that can be implemented is to assure new payloads have a way to “self-terminate” via de-orbit at the end of their life span.  Solar sail technologies, such as NanoSailD2 launched in 2010 have already demonstrated this capability.

Expect reentries also pick up as we approach the peak of solar cycle #24 at the end of 2013 and the beginning of 2014. Increased solar activity energizes the upper atmosphere and creates increased drag on low Earth satellites.

It’s a brave new world “up there,” and hazards, both natural and man-made, are something that space faring nations will have to come to terms with.

-Read and subscribe to the latest edition of NASA’s Orbital Debris Quarterly News for free here.

 

Spacesuit Water Leak Prompts NASA Mishap Investigation

Italian astronaut Luca Parmitano during a spacesuit fit check before his mission. Credit: NASA

In the wake of a spacesuit water leak that sent two astronauts back to the airlock early during a spacewalk last week, NASA has convened a board to look at “lessons learned” from the mishap.

The cause of the leak, which filled Luca Parmitano’s helmet with water, is still being investigated. Some media reports say it may have been a fault within the spacesuit’s cooling system. NASA stated it plans to “develop a set of lessons learned from the incident and suggest ways to prevent a similar problem in the future.”

Chairing the board will be Chris Hansen, the International Space Station’s chief engineer at NASA’s Johnson Space Center in Houston. The other four members, who are all from NASA, include:

  • Mike Foreman, NASA astronaut, Johnson Space Center;
  • Richard Fullerton, International Space Station safety and mission assurance lead, Office of Safety and Mission Assurance, NASA headquarters;
  • Sudhakar Rajula, human factors specialist, Johnson Space Center;
  • Joe Pellicciotti, chief engineer, NASA Engineering and Safety Center, Goddard Space Flight Center.

The July 16 spacewalk stopped early at 1 hour, 32 minutes, far shorter than the crew’s planned 6.5-hour outing. All of the tasks can be easily pushed off to another time, NASA has said. The astronauts were preparing data cables and power for a Russian laboratory module that should reach the station by early 2014, among other tasks.

ISS Astronauts had to scramble to get Luca Parmitano out of his spacesuit after water leaked inside the suit, covering his face. Via NASA TV.
ISS Astronauts had to scramble to get Luca Parmitano out of his spacesuit after water leaked inside the suit, covering his face. Via NASA TV.

During and immediately after the spacewalk, NASA said the crew was in no immediate danger. A few days afterwards, Parmitano reassured officials at the European Space Agency. “Guys, I am doing fine and thanks for all the support. I am really okay and ready to move on,” he said, as reported in an ESA blog post.

Still, there was so much water inside the helmet that after a time, Parmitano had trouble hearing and communicating with his crewmates. “Squeeze my hand if you’re fine,” fellow EVA member Chris Cassidy said to Parmitano during the spacewalk.

NASA also noted there is an engineering analysis happening that is “focused on resolving equipment trouble in an effort to enable U.S. spacewalks to resume.” The board, by contrast, will be looking at aspects such as quality assurance, flight control, operations and maintenance with an eye to improving NASA human spaceflight activities in general.

NASA did not immediately release a date by which it expects the investigation to finish. Meanwhile, at least one news outlet reported that the agency is rushing some spacesuit repair tools on to a Russian Progress supply ship that will leave Kazakhstan for the International Space Station on Saturday.

Source: NASA

Sneak Peeks of the Earth and Saturn Panorama from Cassini on July 19

The Day the Earth Smiled: Sneak Preview. In this rare image taken on July 19, 2013, the wide-angle camera on NASA's Cassini spacecraft has captured Saturn's rings and our planet Earth and its moon in the same frame. Image Credit: NASA/JPL-Caltech/Space Science Institute

The Day the Earth Smiled: Sneak Preview
In this rare image taken on July 19, 2013, the wide-angle camera on NASA’s Cassini spacecraft has captured Saturn’s rings and our planet Earth and its moon in the same frame. Image Credit: NASA/JPL-Caltech/Space Science Institute
See below our wider context mosaic of the Earth, Saturn and its majestic rings[/caption]

Breathtaking raw images of the Earth and Saturn system snapped by NASA’s Cassini spacecraft on July 19 during the worldwide ‘Wave at Saturn’ campaign are streaming back across 1 billion miles of interplanetary space.

Science team members are now busily processing the images to create individual color composites and a panoramic view of the ‘pale blue dot’ and the entire Saturnian system.

NASA just released the first individual color composite focusing on Earth – see above. And its spectacular!

See below our preliminary mosaic showing the Earth in context with nearly half of Saturn and floating in between its incomparably majestic rings.

Partial context mosaic of the Earth and Saturn taken by NASA’s Cassini orbiter on July 19, 2013.   This mosaic was assembled from five wide angle camera raw images.  Credit: NASA/JPL-Caltech/Ken Kremer/Marco Di Lorenzo
Partial context mosaic of the Earth and Saturn taken by NASA’s Cassini orbiter on July 19, 2013. This mosaic was assembled from five wide angle camera raw images and offers a sneak peek of the complete panorama. Credit: NASA/JPL-Caltech/Ken Kremer/Marco Di Lorenzo

To capture all of Saturn and its wide swath of rings, Cassini’s wide angle camera snapped a mosaic of 33 footprints.

“At each footprint, images were taken in different spectral filters for a total of 323 images,” says Carolyn Porco, Cassini Imaging Team leader of the Space Science Institute in Boulder, Colo.

Cassini took the pictures of Earth between 2:27 and 2:42 p.m. PDT on Friday, July 19 from a distance of about 898 million miles (1.44 billion kilometers) away from the home to every human being that has ever lived.

The images show the Earth and the Moon as dots barely about a pixel wide but do reveal the ‘pale blue dot’ that is home to all of humanity and our whitish colored neighbor.

Coincidentally, the first humans (Neil Armstrong and Buzz Aldrin) set foot on the Moon 44 years ago nearly to the day of Cassini’s new images on July 20, 1969.

Distant views of the Earth from our robotic explorers, especially from the outer reaches of our Solar System, are few and far between, and are therefore events for space and astronomy enthusiasts and everyone else to savor.

“One of the most exciting Cassini events in 2013 will be the unusual opportunity on July 19 to image the whole Saturn system as it is backlit by the sun,” explained Linda Spilker, Cassini project scientist of NASA’s Jet Propulsion Laboratory, Pasadena, Calif.

“With Saturn covering the harsh light of the sun, we will be gathering unique ring science and also catching a glimpse of our very own home planet.”

Cassini previously took an absolutely fabulous mosaic of Saturn and Earth back in 2006 that stands as one of the landmark images of the space age.

Besides being picturesque, such mosaics also serve science. For example, the 2006 image “revealed that the dusty E ring, which is fed by the water-ice plume of the moon Enceladus, had unexpectedly large variations in brightness and color around its orbit,” says Spilker.

“We’ll want to see how that looks seven Earth years and a Saturnian season later, giving us clues to the forces at work in the Saturn system. We’ll do this analysis by collecting data from our visual and infrared mapping spectrometer, composite infrared mapping spectrometer and ultraviolet imaging spectrograph in addition to the imaging cameras.”

This simulated view from NASA's Cassini spacecraft shows the expected positions of Saturn and Earth on July 19, 2013, around the time Cassini will take Earth's picture. Cassini will be about 898 million miles (1.44 billion kilometers) away from Earth at the time. That distance is nearly 10 times the distance from the sun to Earth. Image credit: NASA/JPL-Caltech
This simulated view from NASA’s Cassini spacecraft shows the expected positions of Saturn and Earth on July 19, 2013, around the time Cassini will take Earth’s picture. Cassini will be about 898 million miles (1.44 billion kilometers) away from Earth at the time. That distance is nearly 10 times the distance from the sun to Earth. Image credit: NASA/JPL-Caltech

“July 19 marked the first time people on Earth had advance notice their planet’s portrait was being taken from interplanetary distances,” says NASA.

I waved fondly at Saturn and hope you had the chance to wave at Saturn from all across the globe. NASA reports that nearly 20,000 participated in organized events. Countless others waved too.

Cassini was launched in 1997 and achieved orbit at Saturn in 2004. The mission is scheduled to continue until 2017 when it will commit a suicide death dive into the gas giant.

“We can’t see individual continents or people in this portrait of Earth, but this pale blue dot is a succinct summary of who we were on July 19,” said Spilker in a NASA statement.

“Cassini’s picture reminds us how tiny our home planet is in the vastness of space, and also testifies to the ingenuity of the citizens of this tiny planet to send a robotic spacecraft so far away from home to study Saturn and take a look-back photo of Earth.”

Ken Kremer

JPL Waves at Saturn As NASA's Cassini spacecraft turned its imaging cameras to Earth, scientists, engineers and visitors at NASA's Jet Propulsion Laboratory, Pasadena, Calif., gathered to wave at our robotic photographer in the Saturn system on July 19, 2013. Credit: NASA/JPL-Caltech
JPL Waves at Saturn
As NASA’s Cassini spacecraft turned its imaging cameras to Earth, scientists, engineers and visitors at NASA’s Jet Propulsion Laboratory, Pasadena, Calif., gathered to wave at our robotic photographer in the Saturn system on July 19, 2013. Credit: NASA/JPL-Caltech

The Latest from Mars: Dried up Riverbed May Have Flowed into an Ancient Ocean

An artist's rendition of what water on Mars may have looked like. Source Credit: NASA

When it comes to Mars, the hot topic of study is water – a prerequisite for life.

While liquid water is currently not stable on the surface of Mars, there is extensive evidence that it may have been in the past. Astronomers have discovered dried up riverbeds, lake deltas, and evidence of widespread glaciers – to name but a few examples.

However, evidence for a massive standing body of water, such as an ocean, is hard to come by. Early climate models struggle to create circumstances under which liquid water would be stable at all. Nonetheless, an ocean spanning the northern lowlands (approximately one third of the planet) has been long hypothesized.

Scientists at Caltech may have just now confirmed this long-held hope in finding recent evidence for a vast Martian ocean.

The region under investigation is known as Aeolis Dorsa – a plain located at the border between the northern lowlands and the southern highlands. This plain contains many ridges, which are interpreted as ancient river channels.

“These ‘inverted’ channels are now elevated because the coarse sand and gravel carried by the channels is more resistant to erosion than the surrounding mud and silt making up the floodplain material,” Dr. Roman DiBiase, lead author on the study, told Universe Today.

Satellite images of Aeolis Dorsa were collected using the HiRISE camera aboard the Mars Reconnaissance Orbiter.  The resolution was so precise scientists could distinguish features as small as 25 centimeters – an impressive feat even when compared to images of the Earth.

For certain locations “repeat pictures taken with a slight offset enable the creation of stereo-images from which we can determine the relative elevations of features on the planet’s surface,” explains DiBiase. This impressive technique led to high-resolution topographic models, allowing the team to analyze the geometry and patterns of these inverted channels in unprecedented detail.

Not only do the channels spread out toward the end, they also slope steeply downward, forming a delta – a sedimentary deposit that forms where rivers flow into lakes or oceans.

While deltas have been identified on Mars before, all lie within distinct topographic boundaries, such as an impact crater. This is the most compelling evidence for a delta leading into an unconfined region – an ocean.

Final proof of a Martian ocean will advance our knowledge of the intricate interplay between water, climate, and life. “The history of water on Mars has implications not only for the evolution of Martian climate, but also for learning about the early evolution of Earth and Earth’s climate,” explains DiBiase.

As always, further research is needed. Perhaps in the nearby future the Mars Reconnaissance Orbiter and Curiosity will compliment each other quite well – the orbiter taking images from above while Curiosity plays in the dirt, gathering samples in the riverbed.

The study was published in the Journal of Geophysical Research and may be found here.

Super-Moon Monday: The 3rd (& Final?) Act

The gibbous Moon rising rising over the Andes Mountains in Chile. (Credit: @WladimirPulgarG/Flickr).

“Once more into the breach, my dear friends…”

Such a quip may be deemed appropriate as we endured the media onslaught this past weekend for the third and final perigee Full Moon of 2013.

Tonight, on Monday, July 22nd, the Moon reaches Full at 18:15 Universal Time (UT)/4:15 PM EDT. This is only 21.9 hours after reaching perigee, or the closest point in its orbit at 358,401 kilometres from the Earth on the Sunday evening at 20:28 UT. Continue reading “Super-Moon Monday: The 3rd (& Final?) Act”

Expedition 37/38’s Tips For Surviving Long Voyages in Space

Russian cosmonaut Oleg Kotov (left), Expedition 37 flight engineer and Expedition 38 commander; along with NASA astronaut Michael Hopkins (center) and Russian cosmonaut Sergey Ryazanskiy, both Expedition 37/38 flight engineers. Credit: NASA

NASA wants to bring its astronauts outside of Earth. It recently recruited a new astronaut class for deep space voyages. It’s talking about picking up asteroids and possibly heading to the moon or Mars in the distant future. But there are a heck of a lot of steps to do before anyone can head into space for long periods of time.

The agency and Roscosmos are preparing for a one-year voyage to the International Space Station in 2015 that will add to the limited set of data on people being in space consecutively for a year, or longer. You can bet there will be reams of information collected on sleep habits, bone loss, muscle shrinkage, eye pressure and other health factors of concern.

How about the psychological side? The next space station crew to launch gave some hints about how their training prepares them to live cheek-by-jowl in a tiny space for six months.

The mission’s main goal:

The main goal is to put the station in a good condition, and also for the Russian segment, to [install] the new module, MLM (Multipurpose Laboratory Module.) We’re all targeted to this job. Me especially, being the commander of the station, I have the responsibility of the whole crew and their success and also for their psych [psychological] atmosphere. That’s really what I want to do. — Oleg Kotov, Expedition 37 flight engineer, Expedition 38 commander and preparing for his third spaceflight

Receiving advice from past crews:

Sometimes it’s the little things in terms of how to deal with, for example … the food and your clothes and supplies. Other times it’s trying to make sure you’re focusing on the critical items, and not necessarily getting caught up in all the little details [because] you’re going to be there for such a long amount of time.  — Michael Hopkins, Expedition 37/38 flight engineer and rookie astronaut

The Mars 500 long-duration mission vs. flying to the space station:

Mars 500 was really aimed at science. Most of the station [work] is mostly of the safety of the crew and the safety of the station, and then the [next priority is] science. But it also was a great experience to see, psychologically, the space station can be isolating, and how great the influence of this psychology is on the crew. So that was really the experience. Being commander there helps me a lot in my training for real flight.” — Sergey Ryzansky, commander of a 105-day segment as part of phase two of the Mars 500 program, Expedition 37/38 flight engineer and rookie cosmonaut

Michael Hopkins, Expedition 37/38 flight engineer, during spacewalk training. Credit: NASA
Michael Hopkins, Expedition 37/38 flight engineer, during spacewalk training. Credit: NASA

Communications with Mission Control:

Sometimes you ask a question or an item from the ground, and just realizing that you’re not always going to get that answer right away. Sometimes it takes some time for them to determine what the right answer is. — Hopkins

The challenge for other planets:

[I study] how to develop countermeasure means for flights on another planets. After 200 days, for example, flying in space, then we need human beings to work in a spacesuit on the surface of other planets, in different gravity. — Ryzansky

How Hot is the Sun?

How Hot is the Sun?

The Sun is hot, really hot. How hot hot really is, depends on which part you’re talking about:

The sun has a core, a middle, a surface, and an atmosphere.

Starting from the inside out…

There’s the core, where the pressure and temperature are so great that atoms of hydrogen are fused into helium. Every second, 600 million tons of material go through this conversion, releasing vast amounts of gamma radiation. This is the hottest natural place in the Solar System, reaching temperatures of 15 million degrees Celsius. Photons generated at the core of the Sun are emitted and absorbed countless times over thousands of years on their journey to reach the surface.

Outside the core is the radiative zone. Here, temperatures dip down to where fusion reactions can no longer occur, ranging from 7 million down to 2 million degrees Celsius.

Next on our journey outwards from the centre of the Sun, is the convective zone, where bubbles of plasma carry the heat to the surface like a giant lava lamp. Temperatures at the bottom of the convective zone are 2 million degrees.

Finally, the surface, the part of the star that we can see. This is where the temperature is a relatively cool 5,500 degrees Celsius.

Here’s the strange part, as you move further away from the Sun into its atmosphere, the temperature rises again. Above the surface is the chromosphere, where temperatures rise back up to 20,000 degrees Celsius.

Solar CoronaThen there is the corona, the Sun’s outer atmosphere. The corona as a wispy halo around the Sun, visible during eclipses, that stretches millions of kilometres out into space. In the corona, the gases from the Sun are superheated to more than a million degrees – some parts of can even rise to 10 million degrees Celsius.

How can the atmosphere of the Sun get hotter than regions inside it? Astronomers aren’t really sure, but there are two competing theories. It’s possible that waves of energy are released from the surface of the Sun, sending their energy high into the solar atmosphere. Or perhaps the Sun’s magnetic field releases energy into the corona as currents collapse and reconnect.

There are space missions in the works right now to help answer this baffling mystery, so we might have an answer soon.

Stars can get much hotter or colder than our Sun. From the coldest, dimmest red dwarf stars to the hottest blue giants; it’s an amazing Universe out there.

References:
Solar Probe Plus Mission
Solar Orbiter Mission