Wednesday, August 31, 2011

Comet Elenin Gets Hit By A CME & Appears To Be Breaking Apart.

SO MUCH FOR DOOMSDAY: Comet Elenin (C/2010 X1), widely known for inaccurate reports of its threat to Earth, appears to be breaking apart. Observations by amateur astronomer Michael Mattiazzo of Castlemaine, Australia show a marked dimming and elongation of the comet's nucleus over a ten day period:
The behavior of Comet Elenin is akin to that of Comet LINEAR (C/1999 S4), which disintegrated when it approached the sun in back in 2000. Mattiazzo witnessed that event, too. "Yes I did observe the breakup of C/1999 S4 in July 2000," he recalls. "It was quite spectacular watching the nucleus spread out into a cigar shape over a period of days. The apparent breakup of C/2010 X1 is similar, although less visually spectacular."
Comets are fragile objects, easily disrupted by solar heat. As a result, the possible breakup of Comet Elenin, while unexpected, comes as no surprise. Readers with pertinent images are invited to submit them here.

CME 0036: three days before collsion with comet Elenin

Coronal mass ejections, which will collide with comet Elenin three days later. This images taken by coronagraphs COR2, which installed on the STEREO spacecrafts.

Interaction between comet Elenin and coronal mass ejection from the Sun

The real truth about comet Elenin

The long ion tail observed behind the comet Elenin

T. Lovejoy
On the picture taken by the well-known Australian astronomy amateur, Terry Lovejoy, which discovered his comet in 2007, is clearly visible long and thin ion tail stretching almost one degree! Which corresponds to the length of the tail is more than 3,000,000 km! Although this is not a record, the sodium tail of comet Hale-Bopp had a length of nearly 50 million kilometers! Comet Elenin will pass closest to the Earth on October 16 at distance about 35 million kilometers from our planet.

The diameter of the comet Elenin’s coma confirmed by visual observations from the Earth

M. Mattiazzo
My estimate the size of the comet Elenin coma was confirmed by visual observations of an experienced Australian amateur astronomer Michael Mattiazzo. August 19, he estimated the angular size of the coma as 4 arc minutes, which equal to  213,500 km in the linear size. The image of the comet, taken by Michael, on August 19 as you can see on the left and on own author’s site.
I remind, that in the next few days,  we have chances to see the comet C/2010 X1 (Elenin) in the coronagraph COR2 field of view, which mounted on the STEREO spacecrafts.

Comet Elenin Could Be Disintegrating

by Nancy Atkinson on August 29, 2011

C/2010 X1 Elenin, on Aug 29, 2011. Credit: Michael Mattiazzo. Used by permission
Astronomers monitoring Comet Elenin have noticed the comet has decreased in brightness the past week, and the coma is now elongating and diffusing. Some astronomers predict the comet will disintegrate and not survive perihelion, its closest approach to the Sun.

On August 19, a massive solar flare and coronal mass ejection hit the comet, which may have been the beginning of the end for the much ballyhooed lump of ice and dirt.

Comet Elenin as seenby the STEREO HI1-B on Aug. 6, 2011, from about 7 million kilometers from the spacecraft. Credit: NASA/STEREO
“We’ve been following it in the STEREO spacecraft images and a number of amateurs have been following it in their telescopes,” said Australian amateur astronomer Ian Musgrave, author of the Astroblog website. “Shortly after the coronal mass ejection the comet flared up and you could see some beautiful details in the tail, with the tail was twisting about in the solar wind. But shortly after that Earth- bound amateurs reported a huge decrease in the intensity of the comet. We think it may presage a falling apart of the comet.”

One journalist joked that maybe Comet Elenin just couldn’t take all the doomsday talk and publicity.
“It really has been a beautiful little comet and it deserves a better fate than to be overhyped by doom-sayers,” said Musgrave.

Elenin is a long period comet originating from the outer edges of our solar system, and Musgrave noted that comets coming from the Oort cloud which are making their first pass through the solar system tend to be under-performers in terms of brightness. “They don’t brighten as quickly as comets that come around more than once,” he said, “and in looking at the relationship between the brightness and the distance from the Sun, we find empirically that comets that brighten on roughly the same speed as Elenin tend to be likely to fall apart at perihelion.”

However, Musgrave added, each comet is unique. “Some comets will survive and some won’t. The fact that this comet decreased in brightness after the CME, possibly indicates that the comet will not survive. Another possibility is that merely the CME wiped away the coma — the bright cloud of particles around the comet — and the volatiles of the comet might take awhile to come back and recreate the coma, if it does survive.”

Elenin’s mass is smaller than average and its trajectory will take it no closer than 34 million km (21 million miles) of Earth as it circles the Sun. It will make its closest approach to Earth on October 16th, but be closest to the Sun on Sept. 10.

Animation of 5 images taken Aug 19,22,23,27,29 displaying the nucleus of Comet Elenin in the process of disintegrating. Credit: Michael Mattiazzo. Used by permission
Another Australian amateur Michael Mattiazzo has been taking images of the comet (see his website, Southern Comets) and he has noticed that the nucleus appears to be elongating. When that occurs, usually the comet disintegrates or splits apart. Above is an animation Mattiazzo created from images he took of Comet Elenin on August 19, 22, 23, 27 & 29.

You can see a wide-field view of the comet by astrophotographer Rob Kaufmanns, comparing the view from August 19, 23 and 26 at this link.

A similar process took place just a few weeks ago with another comet, 213P Van Ness.
Do comets break apart often?

“You don’t see it it that often, but it happens surprisingly more than people think,” Musgrave said. “Van Ness just happened, but ever couple of years there is a comet that visibly breaks up into fragments, maybe about 6 comets in the last 10 years — excluding the Kreutz-sun-grazer family of comets which split and vaporize on a regular basis.”

A closeup photo of the breakup of Comet S4 LINEAR taken on August 6, 2000 by the European Very Large Telescope (VLT) in Chile. Credit: ESO
Unfortunately, the likely demise of Comet Elenin hasn’t put a lid on the doomsdayers who have predicted earthquakes or three days of darkness or a collision with Earth.

“The doomsdayers are just saying that more bad things will happen!” laughed Musgrave. “But you have to remember that when a comet breaks up, the fragments stay in the same orbit. If it evaporates, you’ll have a mass of rubble and gas on the same orbit. People don’t seem to get that space is big, really big, and when a comet breaks up it follows Newtons Laws and the fragments will slowly draw apart, but over the timescale that we see them, the difference will be so miniscule.”

Sources: Conversation with Ian Musgrave, Astroblog, AstroBob, Southern Comets, STEREO 

Comet double feature: Comets Elenin & Garradd now showing in night sky

Some comets are like old friends, they keep coming back at regular intervals to visit. These are called periodic comets; Comet Halley was the first such comet to be identified, by Edmond Halley back in 1705. It returns to the inner solar system every 75 to 76 years; its last appearance was in 1986 and its next will be in 2061. At present Halley is out just beyond Neptune’s orbit.

Other comets are one-time visitors: they come in to visit us from the Oort Cloud, warm themselves for a few months by the sun, and then head back out to the farthest reaches of the solar system.

There two comets currently visiting the inner solar system — comet Elenin and comet Garradd — so the next two months will provide some excellent opportunities to observe these unusual visitors. 

All comets share one characteristic: they are like "dirty snowballs" in their makeup. Their nucleus of rock and ice, when warmed by the sun, sheds its ice which forms a graceful tail as it’s swept away by the solar wind. Because it’s the solar wind that drives the gas and vapor away, comet’s tails always point away from the sun.

In the sky, many comets appear like ghostly fingers pointing down towards Earth. That is one reason why comets have traditionally been viewed as harbingers of death and disaster. 

The truth about Comet Elenin is that it is a quite ordinary, fairly small comet discovered on Dec. 10, 2010 by Russian amateur astronomer Leonid Elenin using a remote controlled telescope in Arizona.

This comet will pass closest to the sun on Sept. 10 (45 million miles or 72 million kilometers) and closest to Earth on Oct. 16 at a distance of 22 million miles (35 million km.)

Despite the fact that this is a really tiny body, 3 or 4 km. in diameter which will miss the Earth by 22 million miles, the purveyors of gloom and doom have seized upon it as bringing disaster upon the Earth. Please don’t take them seriously, instead try to spot this interesting little object.

At present, comet Elenin is too close to the sun to be viewed from the Northern Hemisphere, though observers south of the equator may catch it low in the western sky after sunset. 

Northern observers' turn will come after the comet passes the sun and starts back out towards the Oort Cloud.

In the last few days of September, Elenin will separate from the sun in our morning sky. It will be visible in binoculars in the morning sky for all of October, and we will publish finder maps then.

        ----Unusual opportunity to observe this comet 

Comet Garradd C/2009 P1 Crossing M71 Globular Cluster in Sagitta Video

by Tammy Plotner on August 29, 2011

Comet Garradd Passes M71 Credit: John Chumack
For the observing weekend warriors, the last few days have been a very exciting time. Not only have we been treated to a supernova event in Messier 101, but we’ve had the opportunity to watch Comet C/2009 P1 Garradd silently slip by Messier 71! Wish you were there? Step inside and you can be…

A few days ago we brought you a “live” broadcast of the comet thanks to Bareket Observatory. Thousands of UT readers had the opportunity to view and enjoy for a full six hours and – thankfully – the weather cooperated. Want to see the results? You can check out the comet video here.

On Friday, August 27th, comet Garradd had another “picturesque” moment… It swept by an often over-looked Messier object – M71.

But it didn’t pass by John Chumack!

At a distance of 1.402 AU from Earth and 2.193 AU from the Sun, Comet Garradd continues to brighten and will reach perihelion on December 23, 2011. ..
Many thanks to John Chumack of Galactic Images for sharing this incredible video with us!

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