What happens to the comet coma?

[brellis]

One of the reasons we rushed New Horizons into space when we did was in order to catch Pluto before its atmosphere of sublimated ice freezes back onto the surface.<br /><br />Does something similar happen to comets? When a comet travels inside 1AU, much of the material is boiled off and gone for good. Does some of the material close to the nucleus refreeze and fall back to the surface? <div class="Discussion_UserSignature"> <p><font size="2" color="#ff0000"><em><strong>I'm a recovering optimist - things could be better.</strong></em></font> </p> </div>

 

[MeteorWayne]

Some does, but probably very little. At 1 AU, the sublimation of ice into gas ejects dust at ~10-100 meters/sec. Those particles and gas are the swept further away by the solar wind and light pressure, forming the tails (dust=sun colored, ionized gas=blue) quickly removing them from the gravity well of the tiny comet nucleus. Of course, a very small percentage does wind up back on the surface <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>