Posted on by Jason Major

How Did Comet Lovejoy Survive Its Trip Around The Sun?

Comet Lovejoy re-emerging from behind the Sun on Dec. 15, 2011. (NASA/SDO)

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It was just about three months ago that the astronomy world watched in awe as the recently-discovered comet Lovejoy plummeted toward the Sun on what was expected to be its final voyage, only to reappear on the other side seemingly unscathed! Surviving its solar visit, Lovejoy headed back out into the solar system, displaying a brand-new tail for skywatchers in southern parts of the world (and for a few select viewers above the world as well.)

How did a loosely-packed ball of ice and rock manage to withstand such a close pass through the Sun’s blazing corona, when all expectations were that it would disintegrate and fizzle away? A few researchers from Germany have an idea.

Scientists from the Max Planck Institute for Extraterrestrial Physics and the Braunschweig University of Technology have hypothesized that Comet Lovejoy managed to hold itself together through the very process that, to most people, defines a comet: the outgassing of sublimated icy material.

As a comet near the Sun, the increased heating from solar radiation causes the frozen materials within the nucleus to sublimate — go directly and suddenly from solid to gas, skipping the liquid middle stage — and, in doing so, burst through the surface of the comet and create the long, hazy reflective tail that is so often associated with them.

Overview of the forces acting on sungrazing comets. (Illustration from paper.)

In the case of Lovejoy, which was on a direct path toward the Sun, the sublimation itself may have provided enough outward force across its surface to literally keep it together, according to the team’s research.

“The reaction force caused by the strong outgassing (sublimation) of the nucleus near the Sun acts to keep the nucleus together and to overcome the tidal disruption,” the paper claims.

In addition, the team states that the size of the comet’s nucleus can be derived using an equation that takes into consideration the combined forces of outgassing, the material composition of the comet’s nucleus, the comet’s own gravity and the tidal forces exerted by the comet’s close proximity to the Sun (i.e., the Roche limit).

Using that equation, the team concluded that the diameter of Comet Lovejoy’s nucleus is anywhere between 0.2 km and 11 km (.125 miles and 6.8 miles). Any smaller and it would have lost too much material during its pass (and had too little gravity); any larger and it would have been too thick for outgassing to provide enough counterbalancing force.

If this hypothesis is correct, taking a trip around the Sun may not mean the end for all comets… at least not those of a certain size!

Watch the video of Lovejoy’s Dec. 15 solar swing below:

The paper was submitted to the journal Icarus on March 8, 2012 by Bastian Gundlach. See the full text here.

Posted on by Jason Major

Giant Sunspot Seen Through Dusty Skies

Sunspot region 1429 photographed from New Mexico. © David Tremblay.

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The enormous sunspot region responsible for all the recent fuss and flares was easily visible from Earth yesterday… easily visible, that is, with the help of a natural filter provided by a New Mexico dust storm!

Photographer David Tremblay captured this image on March 7 through the dust-laden sky of Alto, New Mexico. Active Region 1429 can be seen on the upper right side of the Sun’s disk. Many times the size of Earth, this sunspot region has already erupted with several X-class solar flares and sent numerous CMEs our way — with potential for more to come!

“Blowing dust from the Tularosa Basin is so very dense that observing the sun was possible with the naked eye this evening,” noted David on SpaceWeather.com, where you can see more of his solar photos taken about the same time.

The image above was captured at 560mm with a Canon MKlll ESO1D.

View more of David’s photography here.

Image © David Tremblay. All rights reserved. Used with permission.

Posted on by Nancy Atkinson

A Close-up Look at the Massive Solar Storm that Shook the Sun

Here’s a close look at the large X5.4 solar flare that erupted on the Sun on March 7, 2012 at 00:28 UT, (7:28 PM EST on March 6). These high-definition views from the Solar Dynamics Observatory also show the subsequent solar tsunami that rippled across the Sun, appearing as though the Sun ‘shook’ from the force of the flare.

This storm is heading our way and will likely give Earth’s atmosphere and magnetosphere a little shake as well, but solar physicists aren’t sure yet what the full impact will be. NASA Goddard’s Space Weather Lab and NOAA Space Weather Prediction Center say surely there will be aurorae from this blast. Other potential impacts include some radio blackouts, single-event upsets to satellite operations, and airplane passengers in high latitude, high altitude flights may experience increased radiation exposures.
Continue reading “A Close-up Look at the Massive Solar Storm that Shook the Sun”

Posted on by Jason Major

Sun Releases a Powerful X5 Flare

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Active Region 1429 unleashed an X5.4-class solar flare early this morning at 00:28 UT, as seen in this image by NASA’s Solar Dynamics Observatory (AIA 304). The eruption belched out a large coronal mass ejection (CME) into space but it’s not yet known exactly how it will impact Earth — it may just be a glancing blow.

Solar flares are categorized by a scale according to their x-ray brightness. X is the strongest class, followed by M and then C-class. Within each class the numbers 1 through 9 subdivide the flares’ intensity.

A run-in with an X5-class flare is a major geomagnetic event that can cause radio blackouts on Earth and disrupt satellite operations, as well as intensify auroral activity.

The GOES satellite data for the March 7 flare is below:

The CME is expected to impact Earth sometime on the 8th or 9th. Check back here or at Spaceweather.com for updates on the storm (and any subsequent aurora photos!)

Also, check out the video below, assembled by the SDO team. Just after the X5.4-class flare another smaller X1-class flare occurred, sending a visible wave cross the Sun.


Image courtesy NASA, SDO and the AIA science team. And thanks to Camilla Corona SDO for all the updates!

Posted on by Nancy Atkinson

Sun Unleashes Powerful X-Class Solar Flare

The Sun has been quiet recently but early today (04:13 UTC on March 5, 2012) it unleashed a powerful X1-class solar flare and coronal mass ejection. The latest estimates indicate the CME will probably miss Earth, but hit Mercury and Venus. Even so, the science team from the Solar Dynamics Observatory says that high-latitude skywatchers should still be alert for auroras in the nights ahead. There was also an M2-class eruption from the same big and active sunspot, Active Region 1429, on March 4th which produced another, wider CME that might yet intersect Earth. The cloud is expected to deliver a glancing blow to our planet’s magnetic field on March 6th at 04:30 UT (+/- 7 hrs).

Check the latest forecast of the CME’s arrival from the NASA Goddard Space Weather Lab, which includes a great animation.

So, what’s the difference in the classes of solar flares and how could they affect us on Earth?
Continue reading “Sun Unleashes Powerful X-Class Solar Flare”

Posted on by Jason Major

A Mardi Gras Moon Crossing

SDO AIA image of the Sun and Moon at 14:11 UT on Feb. 21, 2012

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The Sun seems to be glowing in traditional Mardi Gras colors in this image, made from three AIA channels taken today at approximately 14:11 UT (about 9:11 a.m. EST) as the Moon passed between it and the Solar Dynamics Observatory spacecraft. Looks like it’s that time of year again!

During portions of the year, the Moon transits the Sun on a regular basis from the perspective of NASA’s SDO spacecraft, which lies within the Moon’s orbit. When this happens we are treated to an improvised eclipse… and it gives SDO engineers a way to fine-tune the observatory’s calibration as well.

Here are more AIA views of the same event captured in different wavelengths:

Lunar transit on 2-21-12; AIA 304
Lunar transit on 2-21-12; AIA 193
Lunar transit on 2-21-12; AIA 4500

…and here’s an interesting image taken in HMI Dopplergram:

HMI Dopplergram image of transit

While the AIA (Atmospheric Imaging Assembly) images the Sun in light sensitive to different layers of its atmosphere, the Helioseismic and Magnetic Imager (HMI) studies oscillations in the Sun’s magnetic field at the surface layer.

Watch a video of the path of this lunar transit, posted by the SDO team here.

And if you happen to be reading this as of the time of this writing (appx. 10:06 a.m. EST) you can keep up with the latest images coming in on the SDO site at http://sdo.gsfc.nasa.gov/.

It’s Mardi Gras and the Moon doesn’t want to miss out on any of the fun!

Images courtesy of NASA/SDO and the AIA, EVE, and HMI science teams. Hat-tip to Mr. Stu Atkinson who called the AIA alert on Twitter.

Posted on by Nancy Atkinson

Freaky Dancing Plasma on the Sun

Normally plasma from the Sun either shoots off into space or loops back on the Sun’s surface. But the Solar Dynamics Observatory captured some plasma that couldn’t make up its mind. Here, darker, cooler plasma slid and shifted back and forth above the Sun’s surface for 30 hours on February 7-8, 2012. The view is shown in extreme ultraviolet light. As a backdrop, an active region just rotating into view shows bright plasma gyrating into streams — normally how the plasma behaves. SDO scientists say the darker particles are being pulled back and forth by competing magnetic forces, tracking along strands of magnetic field lines.

And by the way, tomorrow is SDO’s 2nd anniversary! It launched two years ago on February 11, 2010. Happy anniversary, SDO and thanks for all the great videos and data so far! We wish you many more!

Posted on by Paul Scott Anderson

New Computer Simulations Show Earth’s Spaghetti-Like Magnetosphere

Supercomputer simulation showing the tangled magnetosphere surrounding Earth. Credit: OLCF

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A new computer simulation is showing Earth’s magnetosphere in amazing detail – and it looks a lot like a huge pile of tangled spaghetti (with the Earth as a meatball). Or perhaps a cosmic version of modern art.

The magnetosphere is formed by the Sun’s magnetic field interacting with Earth’s own magnetic field. When charged particles from a solar storm, also known as a coronal mass ejection (CME), impact our magnetic field, the results can be spectacular, from powerful electrical currents in the atmosphere to beautiful aurorae at high altitudes. Space physicists are using the new simulations to better understand the nature of our magnetosphere and what happens when it becomes extremely tangled.

Using a Cray XT5 Jaguar supercomputer, the physicists can better predict the effects of space weather, such as solar storms, before they actually hit our planet. According to Homa Karimabadi, a space physicist at the University of California-San Diego (UCSD), “When a storm goes off on the sun, we can’t really predict the extent of damage that it will cause here on Earth. It is critical that we develop this predictive capability.” He adds: “With petascale computing we can now perform 3D global particle simulations of the magnetosphere that treat the ions as particles, but the electrons are kept as a fluid. It is now possible to address these problems at a resolution that was well out of reach until recently.”

It helps that the radiation from solar storms can take 1-5 days to reach Earth, providing some lead time to assess the impact and any potential damage.

The previous studies were done using the Cray XT5 system known as Kraken; with the new Cray XT5 Jaguar supercomputer, they can perform simulations three times as large. The earlier simulations contained a “resolution” of about 1 billion individual particles, while the new ones contain about 3.2 trillion, a major improvement.

So next time you are eating that big plate of spaghetti, look up – the universe has its own recipes as well.

The original press release from Oak Ridge National Laboratory is here.

Posted on by Nancy Atkinson

“Bad Boy” Sunspot Unleashes Powerful X-Class Flare

The active region on the Sun that created all the hubbub and aurorae earlier this week put out one last shot before that area of the Sun turns away from Earth’s view. And that shot was a biggie. At 18:37 UT (1:37 pm EST) today (January 27, 2012) sunspot 1402 unleashed an X-class flare, the largest and most powerful category of flares. This flare was measured as an X2, which is at the low end of the highest powered flares, but still, this is the most powerful flare so far this year. It was not directed at Earth, but scientists from the Solar Dynamics Observatory say the energetic protons accelerated by the blast are now surrounding our planet and a S1-class radiation storm is in progress. S1-class is the lowest of 5 (S1 to S5) and has no biological impact, no satellite operations are impacted but some minor impact on HF radio could be experienced.

With all the activity from the Sun, you might need a refresher course in solar flares. Here’s a guide from SDO, and what all the different classifications are:
Continue reading ““Bad Boy” Sunspot Unleashes Powerful X-Class Flare”