Zombie ISON ‘Behaving Like A Comet’, Stunned Astronomers Say

Talk about the Comeback Kid. After Comet C/2012 S1 ISON rounded the sun yesterday afternoon, professional astronomers around the world looked at the faded debris and concluded it was an “ex-comet.” NASA wrapped up an hours-long Google+ Hangout with that news. The European Space Agency declared it was dead on Twitter.

But the remnants — or whatever ISON is now — kept brightening and brightening and brightening in images from the NASA/European Space Agency Solar and Heliospheric Observatory. The pictures are still puzzling astronomers right now, almost a day after ISON’s closest encounter with the sun.

 

You can follow our liveblogged confusion yesterday, capped by a gobsmacking announcement from the Naval Research Laboratory’s Karl Battams, “We believe some small part of ISON’s nucleus has SURVIVED perihelion,” he said on Twitter. Since then, Battams wrote a detailed blog post, referring to images from the Large Angle and Spectrometric Coronagraph (LASCO) aboard SOHO:

“Matthew [Knight] and I are ripping our hair out right now as we know that so many people in the public, the media and in science teams want to know what’s happened. We’d love to know that too! Right now, here’s our working hypothesis: As comet ISON plunged towards to the Sun, it began to fall apart, losing not giant fragments but at least a lot of reasonably sized chunks. There’s evidence of very large dust in the form of that long thin tail we saw in the LASCO C2 images.

After its closest approach to to the sun on Nov. 28 (left), Comet ISON appeared a dim shadow of its former self (at right). "The comet may still be intact," NASA wrote on Nov. 29. Images from the Solar and Heliospheric Observatory. Credit: ESA/NASA/SOHO/Jhelioviewer
After its closest approach to to the sun on Nov. 28 (left), Comet ISON appeared a dim shadow of its former self (at right). “The comet may still be intact,” NASA wrote on Nov. 29. Images from the Solar and Heliospheric Observatory. Credit: ESA/NASA/SOHO/Jhelioviewer

Then, as ISON plunged through the corona, it continued to fall apart and vaporize, and lost its coma and tail completely just like Lovejoy did in 2011. (We have our theories as to why it didn’t show up in the SDO images but that’s not our story to tell – the SDO team will do that.) Then, what emerged from the Sun was a small but perhaps somewhat coherent nucleus, that has resumed emitting dust and gas for at least the time being. In essence, the tail is growing back, as Lovejoy’s did.

So while our theory certainly has holes, right now it does appear that a least some small fraction of ISON has remained in one piece and is actively releasing material. We have no idea how big this nucleus is, if there is indeed one. If there is a nucleus, it is still too soon to tell how long it will survive. If it does survive for more than a few days, it is too soon to tell if the comet will be visible in the night sky. If it is visible in the night sky, it is too soon to say how bright it will be…

This morning (EST), Battams succinctly summarized the latest images he saw: “Based on a few more hours of data, comet #ISON appears to be… well, behaving like a comet!”, he wrote on Twitter.

NASA issued a status update this morning saying it’s unclear if this leftover is debris or an actual nucleus, but added that “late-night analysis from scientists with NASA’s Comet ISON Observing Campaign suggest that there is at least a small nucleus intact.” NASA, as well as Battams, pointed out that comet has behaved unpredictably throughout the 15 months scientists and amateurs have been observing it.

Mike Hankey of Monkton, Maryland took this photo of Comet ISON in outburst this morning Nov. 14. The tail now shows multiple streamers. Click to enlarge. Credit: Mike Hankey
Mike Hankey of Monkton, Maryland took this photo of Comet ISON in outburst Nov. 14. The tail showed multiple streamers. Click to enlarge. Credit: Mike Hankey

Throughout the year that researchers have watched Comet ISON – and especially during its final approach to the sun – the comet brightened and dimmed in unexpected ways.  Such brightness changes usually occur in response to material boiling off the comet, and different material will do so at different temperatures thus providing clues as to what the comet is made of.  Analyzing this pattern will help scientists understand the composition of ISON, which contains material assembled during the very formation of the solar system some 4.5 billion years ago.

Slate Bad Astronomy blogger Phil Plait jokingly threw out phrases like “What the what?” on Twitter yesterday, but added in a late-night update: “If you haven’t figured this out yet: We are *loving* this. The Universe surprises us yet again! How awesome!” He continued with his astonishment in a blog post:

For those keeping score at home, it got bright, then it faded, then it got all smeared out, then it came around the Sun smeared out, and then it seemed to get its act together again. At this point, I refuse to make any further conclusions about this comet; it seems eager to confuse. I’ve been hearing from comet specialists who are just as baffled… which is fantastic! If we knew what was going on, there’d be nothing more to learn.

Science confusion: Comet ISON made its closest approach to the sun Nov. 28. Although it showed up again in images from the Solar and Heliospheric Observatory, scientists could not spot it using the ESA PROBA-2 spacecraft (view pictured). ISON's composition or proximity to the sun may have caused this. Credit: PROBA-2 Science Centre
Science confusion: Comet ISON made its closest approach to the sun Nov. 28. Although it showed up again in images from the Solar and Heliospheric Observatory, scientists could not spot it using the ESA PROBA-2 spacecraft (view pictured). ISON’s composition or proximity to the sun may have caused this. Credit: PROBA-2 Science Centre

In a series of Twitter posts this morning, the European Space Agency’s science feed offered this take from Gerhard Schwehm, ESA’s head of planetary science:

From my initial look at ISON in today’s SOHO images, it seems nucleus has mostly disintegrated. Will only know if part of ISON nucleus has survived by continuing observations and performing more analysis. Bright fan-shape implies lots of material was released and travelling along ISON orbit, not confined in a traditional tail. Would be interesting to learn more about composition of debris to help us piece together what’s happened, but we need more time.

Other spacecraft searching for ISON were not able to spot it. For ESA’s PROBA-2, it may have been because of its composition or proximity to the sun, but scientists are unsure. It was also invisible in NASA’s Solar Dynamics Observatory; “scientists are still looking at the data to figure out why,” an agency Twitter update stated this morning.

So to sum up: no one’s quite sure of what is happening now, or what is happening next, but we will keep you posted and let you know if and when you can see ISON again in your home telescopes.

One of the finest pictures to date of Comet ISON by ace astrophotographer Damian Peach taken on Oct. 27.
One of the finest pictures to date of Comet ISON by ace astrophotographer Damian Peach taken on Oct. 27.

Spacecraft Witnesses Solar Eclipse x 3

On the ground, the total solar eclipse of November 13/14, 2012 was only visible to only to observers in northern Australia. But ESA’s Sun-watching satellite Proba-2 enjoyed three partial eclipses from its vantage point in space.

During a total solar eclipse, the Moon moves in front of the Sun as seen from Earth, their alignment and separation such that the much closer Moon appears large enough to block out the light from the much more distant Sun.

Since Proba-2 orbits Earth about 14.5 times per day, it can dip in and out of the Moon’s shadow around the time of a solar eclipse. The constant change in viewing angle of Proba-2 meant that the satellite passed through the shadow three times during the eclipse yesterday, as shown in the video above.

ESA says the apparent noise in the movie results from high energy particles hitting Proba-2’s electronics as the spacecraft passes through the South Atlantic Anomaly. The dimming in the movie is an effect as part of the satellite’s orbit passes through the shadow of the Earth.

Proba-2 image of the solar disc taken during the total eclipse of July 2010, combined with ground-based images taken at the same time to reveal the exquisite details of the solar corona. Credit: ESA

Read more about Proba-2’s day of eclipses from ESA.

Stunning Timelapse: Spacecraft Capture the Transit of Venus

Here’s the entire 7-hour transit of Venus across the face of the Sun – shown in several views — in just 39 seconds, as seen by the Solar Dynamics Observatory on June 5, 2012. This view is in the 171 Angstrom wavelength, so note also the the bright active region in the northern solar hemisphere as Venus passes over, with beautiful coronal loops visible. The transit produced a silhouette of Venus on the Sun that no one alive today will likely see again. With its specialized instruments SDO’s high-definition view from space provides a solar spectacular!

Scott Wiessinger from NASA Goddard’s Scientific Visualization Studio wrote this morning to tell us, “If you have the space and the bandwidth, I really recommend downloading this large file on the SVS to view. YouTube compression is hard on solar footage, so it looks even better when you watch it at true full quality.”

Below is a composite image from SDO of Venus’ path across the Sun, as well as another great timelapse view from ESA’s PROBA-2 microsatellite:

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This movie shows the transit of Venus as seen from SWAP, a Belgian solar imager onboard ESA’s PROBA2 microsatellite. SWAP, watching the Sun in EUV light, observes Venus as a small, black circle, obscuring the EUV light emitted from the solar outer atmosphere – the corona – from 19:45UT onwards (seen on the running timer on the video). At 22:16UT – Venus started its transit of the solar disk.

Venus appears to wobble thanks to the slight up-down motion of Proba-2 and the large distance between the satellite and the Sun.

The bright dots all over the image, looking almost like a snow storm, are energetic particles hitting the SWAP detector when PROBA2 crosses the South Atlantic Anomaly, a region where the protection of the Earth magnetic field against space radiation is known to be weaker.

And as if the Sun is just showing off, a Coronal Mass Ejection is visible as well towards the end of the video, seen as a big, dim inverted-U-shape moving away from the Sun towards the bottom-right corner. This is a coronal mass ejection bursting out from the Sun.

The May 2012 Annular Eclipse as Seen From Space

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Here’s a few unique vantage points of seeing the annular solar eclipse on May 20/21 2012. Above, one of the geostationary satellites called MTSAT (Multi-Functional Transport Satellite) built by Japan was able to capture the shadow over Earth near the maximum of the eclipse of May 20-21, 2012. It’s rather amazing how small the shadow is! “This image was generated during a color test of our Visible Daily-Earth project,” wrote Abel Mendez Torres on the [email protected] Arecibo website “and was taken by the MTSAT on May 21, 2012 @ 000 UTC (May 20, 2012 @ 8:00 PM EDT). Color correction was based on NASA Visible Earth datasets.” The Planetary Habitability Laboratory (PHL) is a research and educational virtual laboratory that studies of the habitability of Earth, the Solar System, and extrasolar planets, and @ProfAbelMendez is a very interesting person to follow on Twitter.

Below are a couple of videos: even though you are not supposed to look directly at the Sun during an eclipse, the PROBA-2 satellite did with an awesome result, and astronaut Don Pettit’s exceptional view of the eclipse from the International Space Station, as well as a view from the Hinode and Terra satellites:

ESA’s space weather microsatellite Proba-2 observed the solar eclipse on the evening of May 20, 2012. It passed through the Moon’s shadow a total of four times, imaging a sequence of partial solar eclipses in the process. The first contact was made on Sunday May 20 at 21:09 GMT. The last contact finished at 03:04 GMT.

Don Pettit’s view:

The joint JAXA/NASA Hinode mission captured this images of an annular eclipse of the Sun on May 20, 2012. Credit: Hinode/JAXA/NASA

Also, the JAXA/NASA Hinode mission captured this video of the eclipse.

Here’s a view of the eclipse over the North Pacific Ocean as see by the Terra satellite:

Credit: NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team

The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Terra satellite captured this true-color image of the annular solar eclipse over the North Pacific Ocean on May 20, 2012. Credit: NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team

Make sure you check out our gallery of eclipse images from around the world, too!

Great View! January 4 Solar Eclipse As Seen From Space

Here’s a unique view of the January 4 partial solar eclipse: ESA’s sun-watching microsatellite Proba-2 captured the conjunction of the spheres as the Sun, Moon and Earth all lined up in front of it. Shortly after the Moon partially blocked Proba-2’s view of the Sun, the satellite flew into Earth’s shadow. At that point – when the video seen here goes dark – the Sun, Moon, Earth and Proba-2 were all on the same line in space.

“This is a notable event,” said Bogdan Nicula of the Royal Observatory of Belgium (ROB), who calculated where and when this double-eclipse would happen. “It is a nice exercise to model the orbit and relative positions of all three celestial bodies.”
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