Hi everyone,

APOD today carries a magnificent picture of the comet as seen from the Southern hemisphere and taken by the discoverer from a sight in Australia
http://antwrp.gsfc.nasa.gov/apod/astropix.html

My questions are:
1. Why is the tail curved to such an extent?
2. What causes the breakup of the tail?

I have tried to answer my own questions as follows:

The tail is curved because the comet is moving away across the solar wind direction. The tail lags behind as it is still driven by the solar wind and unrelated to the direction of the movement of the comet..
The tail is broken up by the solar wind.
I would value your thougths on this.

Phil

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As I undertsand it, the reason for the tail streaching behind he comet the way it does is similar to the effect the way the water comes out of a hosepipe that is moved sideways suddenly.

The broken-up appearance of the tail presumably is connected with the effect of the comet's core rotating and when "softer" parts point towards the Sun, the boil-off increases. Also, if the nucleas is highly oval, it will see different exposure to the Sun as it rotates, boiling off different amount out gas.

Truly a Great Comet!
Willie

What you are seeing is the dust tail, not the plasma tail, so it does indeed follow the movement of the comet.

How come we only see the comet going away in everybody's pictures?

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What do you mean by "going away"?

Going in the opposite direction of the photographer.

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Nikon D200
Nikon D50
Nikon 300mm F4D ED-IF AF-S
Nikon 50mm F1.8
Sigma 70-200mm F2.8EX DG Macro
Sigma 24-70mm F2.8EX DG Macro

How can you tell which way it is going from a single photograph?

Yeh, it's an illusion that the comet appears to be moving away. Remember that the tail will always point away from the sun so it's possible that the comet could be moving into it's tail. In fact I believe it is at the moment.

As far as I understand it, the comet has already gone around the sun and is heading back out into space. When the comet came close to the sun, frozen gasses heated up and were thrown out by the solar wind. This process continued to occur up until now. That's why you can see such a large tail in the photograph. It's all the particles and gas thrown out by the solar wind from when the comet approached the sun, swung around it and started heading back out.

Actually, a comet has two tails. The ion tail will always point away from the sun, as it is affected by the solar wind. The dust tail points somewhat away from the sun, as the dust particles are affected by solar radiation, but tend to drift behind the comet in its orbit.


See, for example, http://antwrp.gsfc.nasa.gov/apod/ap001227.html

APOD (February 1st) features a discussion on the fascinating tail of the comet.

http://antwrp.gsfc.nasa.gov/apod/astropix.html

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