Comet Goes Bye-bye As Sun Goes Boom

The picture at left was taken with the C2 coronagraph aboard the space-based SOHO telescope and shows the comet just before it slid behind the occulting disk (red circle). Could the brightening in its tail be disintegrating fragments from the comet's head vaporizing in the solar heat? The right side photo, taken a few hours later, shows a spectacular CME. Credit: NASA/ESA

Our bright little comet didn’t make it yesterday, but its death was marked in spectacular fashion by a coincidental CME or coronal mass ejection from the sun’s eastern hemisphere very near the time of the comet’s perihelion, or in this case, its final end. Too bad no one could see this comet visually because of how close it was to the sun, but thanks to SOHO, we can watch its demise frame by frame. Check it out the action at this link. You’ll want to scroll down to the pictures marked either C2 (narrower, more magnified view of the sun and corona) or C3 (wide field). A good place to start is with the picture labeled 20111001_1330_c3.gif

A sketch made at the time of Comet Tewfik, also known as the "Eclipse Comet", near the eclipsed sun.

I like to think that had there been a total solar eclipse yesterday, the view of the brilliant comet so near the sun would have been an unforgettable sight. This actually happened on May 17, 1882 when a team of astronomers gathered in Egypt to observe and photograph a total eclipse of the sun. During the middle of totality observers noted a “luminous streak” near the sun about the brightness of the corona. There were no coronagraphs in those days, and no one was expecting a comet, so it came as a surprise. One observer noted that the nucleus or central brightening inside the comet’s coma was sharply defined and the tail curved. Read more about Comet Tewfik HERE.

Right around the time of the comet’s impact or vaporization by the sun, a large coronal mass ejection (CME) erupted from the left or eastern side of the sun. CMEs are huge bubbles of gas threaded with bits and pieces of the sun’s magnetic field often associated with eruptions of solar flares. If directed toward Earth – and this one wasn’t – CMEs can affect radio communications, damage sensitive satellite electronic components, kick-start an awesome display of northern lights or overload unprotected power grids causing blackouts.

What’s curious is the timing. Half a dozen CMEs can happen every day, so it’s most likely a coincidence that this one occurred at nearly the same time as the comet’s destruction. After all, the comet was somewhere in the range of 100 feet across while the sun is 864,000 miles in diameter –  too much even for a replay of David and Goliath. Since fragments of this group of Kreutz comets rain down on the sun regularly without a CME to show for their sacrifice, it’s hard to assert a connection, yet astronomers have observed more than a few coincidental pairings. Perhaps future studies may show a relationship.

Use this map to help you identify the four most prominent lunars seas tonight. Can you still see the dimly-lit left side of the moon. It's illuminated by sunlight reflected off the Earth. Created with Stellarium

Let’s cool things down a notch and take a look at the thick crescent moon this evening. It will hang low in the southern sky along the Scorpius-Sagittarius border. The dark patches you’ll see are called lunar “seas” or “maria” (MAH-ree-uh) in Latin. Can you spot all four with your naked eye? If so, your vision is excellent. If not, binoculars will show them plainly. The seas are vast plains of solidified lavas that oozed and bubbled their way to the surface filling the large basins left by earlier asteroid impacts. The surrounding white-toned areas are called the lunar highlands and are the remainder of the moon’s original crust, now saturated with impact craters from bombardments four billion years ago.

9 Responses

  1. Inverse

    Bob, on Saturday in the southern hemisphere it was cloudy and it looked like two suns shining through the clouds. One large (the real sun) and a smaller one just to the right (to far over to be shining from the same source). I thought maybe it was a daytime moon shining through the cloud but could it have been the comet? It was early in the day about 8:30am Australasia.

    1. astrobob

      Inverse,
      It would be nice, but I don’t think so. The comet would have been rather faint at that time, and even at brightest, would have been too close to the sun to see with the naked eye. Even Venus at magnitude -4 (considerably brighter than the comet) would be impossible to see with the naked eye so close to the sun. Is it possible you saw a sundog? Another possibility is that the sun was “split” by that intervening cloud bank. I’ve seen videos showing this in a striking way.

  2. gin

    This woman in facebook has all her friends riled up over this.. i’m sure you can imagine.
    Anyway, she says one source told her it is directed at earth. Can you give us some more detail on that?
    I’m not overly worried but i’m a little tired of panic driven nonsense and chicken little syndrome.
    Thanks!

    1. astrobob

      Gin,
      No need to be riled one way or the other. The CME that occurred at the same time when the comet vaporized away was off to the left or east side of the sun and not directed toward Earth. However other CMEs connected to large sunspot groups closer to the center of the sun’s face (groups 1302 and 1305) have been directed our way and have been responsible for some of the auroras we’ve had of late.

  3. gin

    One major issue is her worry over the earth frying on the 4th…. I think that part has upset people the most.

    1. astrobob

      Gin,
      You may have missed this detail in the blog, but CMEs happen about six times per day. They are part of the sun’s routine. Some are larger, some smaller. Some can have effects on Earth in terms of the effects I wrote about in the blog. Others miss the Earth completely and have no effect.

  4. Simon

    Bob,

    Your info may be incorrect. There were multiple CMEs triggered, and there is indeed a large Earthbound CME from sunspot 1305 heading towards us. Expected impact in the next day or so.

    1. astrobob

      Hi Simon,
      The CMEs you refer to happened at different times in different sunspot groups near the center of the sun’s disk. Since those face the Earth, they did send material in our direction. They’re unrelated to the CME that happened at the same time the comet disappeared. That one popped off the far eastern limb of the sun and was not Earth-directed. That was the only CME I was referring to in the blog.

  5. Inverse

    Bob, think you are right about the split in clouds, thinking about it the edge of the smaller area of bright cloud was white so may have created a strange reflection. It was not a sun dog as I doubt that would have the brightness to shine through reasonably thick cloud.

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