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Comets "running on the spot"

Posted: 24 Dec 2018 03:49
by SpacyLuke
1) Why do comets like: Halley and Halley Bopp "run on the spot" and dont even change their location in space ? 
(other comets ive seen do change their location)
When you speed up time they just spin very fast in the same place .
2) Why do those comets mentioned above not have nice shiny tails like some of the others in SE ?

log:

Comets "running on the spot"

Posted: 24 Dec 2018 05:03
by Mosfet
Halley's comet has nearly reached aphelion right now, which is the most distant point from the Sun of its orbit. Kepler's third law shows how in a very elongated elliptical orbit, as it's typical with periodic comets, the orbital velocity near its aphelion is very low. Hale-Bopp it's moving towards its aphelion which is even farther than Halley's.
So, they're not fixed in its orbits, they're just extremely slow, as you can see if you accelerate time speed 10[sup]6[/sup] times.

Comet tails are the result of dust particles and gases, heated by solar radiation. The amount of energy that those comets receive when they are far from the Sun is not enough to make that tail apparent, in fact we could say that there's a direct correlation between their distance from the Sun and their tail appearance, also depending on the relative composition of the comet.
SpaceEngine depicts that.

Comets "running on the spot"

Posted: 24 Dec 2018 05:24
by SpacyLuke
Ok. Thank you for the explanation.
If you celebreate Christmas: Merry Christmas ! :)

Comets "running on the spot"

Posted: 24 Dec 2018 13:55
by Julian
Set the date to July 28, 2061 if you want to see the next perihelion of Halley's Comet.

Comets "running on the spot"

Posted: 24 Dec 2018 20:54
by SpacyLuke
Wow !  Nice one Julian ! :) 
Looks beautiful !