FreeLists / az-observing / [AZ-Observing] Re: Virtual Observing of Comet Bradfield C/200 4 F4

["Tom Polakis" <tpolakis@xxxxxxx>]

Jack Jones wrote:

> Why isn't the tail pointing away from the sun like in animations? Looks 
like a flyby.


I think it's because the velocity of the comet when it is so close in to 
the sun has a much larger effect than the solar wind.  The solar wind 
blows a dust particle back, but it is "left behind" as the comet whistles 
past the sun.  Look closely, and you can see a bit of a curved, parabolic 
trajectory to the tail.  We typically see comets much farther out than 0.2 
a.u., so the solar wind effect dominates over their velocity.


Here's what John Bortle wrote about it on another list:

Attempting to keep things in the simplest terms I can, comets that 
pass very close to the Sun (Bradfield is currently about 0.2 AU out) 
display very strongly curved tails that follow far behind the 
imaginary line joining the Sun and comet. In Bradfield's case we also 
have the situation that we are observing the comet's orbital plane 
almost edge-on so our view is extremely oblique...in fact, almost 
looking down the tail's root. The two situations combine to produce 
most of the observed seeming distortion.

More striking, however, has been the dramatic, and very rare, forward-
scattering event seen during the past 72 hours, temporarily 
brightening the comet by 3 magnitudes or more over predictions!

John Bortle

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