Quote:
Originally Posted by petermcgain  There's some really interesting info on this thread, but I have a couple more queries, if only to answer people who are asking me questions simply because I keep telling them there's a comet in the sky and they should be looking at it! It hasn't appeared to move very much in relation to Perseus - how fast is it actually travelling and in which direction is it going and for how long will it remain visible? Sorry, that's three questions. |
First-off
How long will it be visible?
Well - as it disperses, it's getting dimmer - still naked-eye, but may not be for much longer. Will probably be a binocular/small telescope object for at least a few weeks after that though.
I made this little chart more than a week ago - it shows Holmes' track against the sky - it is currently MUCH closer to Mirfak than in that chart, VERY close now, and expected to pass 'above' Mirfak on 19th/20th Nov (tonight/tomorrow)
It'll probably no longer be naked-eye by the time it gets much beyond the end of the dotted line on that chart.
As for it's ACTUAL speed - not sure, but a quick work-out.........
Average orbital radius - about 3.6 AU (335 million miles)
*1AU is the average distance of Earh from the Sun - about 93 million miles*
(335 million x 2) multiplied by 'pi' gives the distance it travels in one orbit....
2105 million miles
One orbit takes about 6.9 years - so 2105 / 6.9 = 305 million miles per year
305 mil / 365 = 835,000 miles a day
Or roughly 35,000 mph
***important note***
These figures are by no means accurate - they are only a rough 'ball-park' estimate.
Above figures are all worked out from averages - comets have an elliptical orbit, and travel faster when near 'perihelion' (nearest point to the Sun - and slower at 'aphelion' (furthest point)
Holmes is currently headed out towards aphelion, so should be going slower than that 35,000 mph.