What makes an asteroid an asteroid and not a comet

In summary, comets are objects with highly elliptical orbits that spend a significant amount of time far from the sun, allowing their gasses and ices to remain intact and form a tail when they approach the sun. On the other hand, asteroids have more circular orbits and are closer to the sun, causing them to lose their gasses and ices and not form a tail. The distinction between the two is primarily based on their appearance and can be arbitrary, as any rock can potentially become either depending on its interactions. The Oort cloud is a possible explanation for the origin of comets, which are essentially asteroids with little to no volatiles on their surface.
  • #1
raknath
61
0
Hi all


Have been thinking about this for sometime, what is the fundamental difference that makes an asteroid an object orbitting around the star at a lesser speed and not a comet?

Hope my question is clear, framing it otherwise why do asteroids not turn into raging comets or comets into sedate asteroids?

Thanks again :smile:
 
Astronomy news on Phys.org
  • #2
raknath said:
Hi all


Have been thinking about this for sometime, what is the fundamental difference that makes an asteroid an object orbitting around the star at a lesser speed and not a comet?

Hope my question is clear, framing it otherwise why do asteroids not turn into raging comets or comets into sedate asteroids?

Thanks again :smile:

Comets are almost exclusively in highly elliptical orbits (why we only see them every hundred years). This is thought to be because they were objects ejected (by some form of gravitational pertubation) from the Kuiper belt or Oort Cloud. An object in such a highly elliptical orbit spends a comparatively low amount of its life near enough to the sun to remove any gasses and melt any ices (what we observe as the comet's tail). An asteroid close enough to the sun would be stripped of these elements within a fairly short period of time.

Though, the distinction is based almost solely on their appearance. Certainly an asteroid in the outer solar system could have the same composition as a comet which streaks through the solar system with a fairly long period. The difference is, because the asteroid is in a (much more) circular orbit, there is no perceptible change in its appearance (increase in luminosity), so they go undiscovered. If someone were to magically throw it towards the inner solar system, it would appear the same.
 
  • #3
What you are basically saying is that random gravitational perturbances cause the asteroid/stellar body to assume some extra velocity which in turn is added on by the gravitational pull of the star near it and hence it becomes a comet

Am i correct then in assuming that the flip-flop between an asteroid and comet is a matter of pure chance?
 
  • #4
raknath said:
Am i correct then in assuming that the flip-flop between an asteroid and comet is a matter of pure chance?
It's an arbitrary definition, like the split between a planet and an asteroid.
Any rock can become either depending on it's interactions.
 
  • #5
mgb_phys said:
It's an arbitrary definition, like the split between a planet and an asteroid.
Any rock can become either depending on it's interactions.

comets have more ice or frozen gas to form a tail
and fewer hard high melting stuff in them
a rocky or metal asteroid will not form a tail
unless it gets so close to the sun to melt
the rock or metal

has there ever been a rock or metal comet without ice
 
  • #6
ray b said:
comets have more ice or frozen gas to form a tail
and fewer hard high melting stuff in them
what does a comet become when all it's ice has evaporated?

has there ever been a rock or metal comet without ice
Most of them, it only takes a few 1000s orbits for most to lose all their volatiles.
 
  • #7
mgb_phys said:
what does a comet become when all it's ice has evaporated?


Most of them, it only takes a few 1000s orbits for most to lose all their volatiles.

but at that point it is no longer a comet!
but a asteroid with a odd orbit
 
  • #8
The Oort cloud, as Nabeshin noted, is the short answer. An asteroid is essentially a comet with little or no volatiles on its surface [such as ice]. Asteroids typically have orbits within the confines of Jupiter's orbit. See
http://nasm.si.edu/research/ceps/etp/comets/comet_orbits.html
 
  • #9
Any rock IMO can become an ice ball far enough into space, which possibly explains why comets originate at the Oort cloud?
 

What is an asteroid?

An asteroid is a small, rocky object that orbits the sun. They are typically made up of rocky or metallic material and can range in size from a few meters to hundreds of kilometers in diameter.

What is a comet?

A comet is a small, icy object that also orbits the sun. They are typically made up of ice, dust, and rocky material and can range in size from a few meters to tens of kilometers in diameter.

What is the main difference between an asteroid and a comet?

The main difference between an asteroid and a comet is their composition. Asteroids are primarily made up of rocky or metallic material, while comets are primarily made up of ice and dust. Additionally, comets often have a distinct tail when they pass close to the sun, while asteroids do not.

How are asteroids and comets formed?

Asteroids and comets are believed to have formed from the leftover material from the formation of the solar system. Asteroids formed closer to the sun, where it was too warm for ice to form, while comets formed farther away, where it was cold enough for ice to exist.

Can an asteroid become a comet or vice versa?

It is possible for an asteroid to become a comet if it gets close enough to the sun and its surface begins to heat up, causing ice to melt and form a tail. However, this transformation is rare and most asteroids and comets maintain their original identities throughout their lifetimes.

Similar threads

  • Astronomy and Astrophysics
Replies
4
Views
2K
  • Astronomy and Astrophysics
Replies
30
Views
1K
  • Astronomy and Astrophysics
Replies
5
Views
1K
  • Astronomy and Astrophysics
Replies
5
Views
2K
  • Astronomy and Astrophysics
Replies
14
Views
387
  • Astronomy and Astrophysics
Replies
7
Views
2K
  • Astronomy and Astrophysics
2
Replies
50
Views
3K
Replies
16
Views
2K
Replies
11
Views
3K
Replies
17
Views
2K
Back
Top