<p>You've answered your own question there, the difference between the two is that asteroids are rock whereas comets are made up of ice and dust.  An asteroid doesn't heat up when it gets close to the Sun and doesn't produce a tail.  Comets can orbit the Sun or any star in a long elliptical (Comet West) or short elliptical (Comet Encke 3.3 Years) period whereas asteroids are found in the Asteroid Belt between Mars and Jupiter and in the Kuiper Belt.  Sedna is a long period asteroid further out any other object in the solar system but it is still an asteroid according to what we know. <a href="https://www.universeguide.com/fact/comets" rel="nofollow">https://www.universeguide.com/fact/comets</a>  <a href="https://www.universeguide.com/fact/asteroids" rel="nofollow">https://www.universeguide.com/fact/asteroids</a></p>

CC BY-SA 3.0
2014-10-11T11:33:52.450Z
2014-11-05T18:40:23.133Z
2014-11-05T18:40:23.133Z
John whitworth
<p>Although the difference between asteroid and comets is quite distinct, there are examples which blurs this line. From <a href="https://en.wikipedia.org/wiki/Comet" rel="nofollow noreferrer">Comets (Wikipedia)</a>:</p>
<blockquote>
<p><a href="https://en.wikipedia.org/wiki/Extinct_comet" rel="nofollow noreferrer">Extinct comets</a> that have passed close to the Sun many times have lost nearly all of their volatile ices and dust and may come to resemble small asteroids. Asteroids are thought to have a different origin from comets, having formed inside the orbit of Jupiter rather than in the outer Solar System. However, In the early 21st century, the discovery of some minor bodies with long-period comet orbits, but characteristics of inner solar system asteroids, were called <a href="https://en.wikipedia.org/wiki/Manx_comet" rel="nofollow noreferrer">Manx comets</a>. They are still classified as comets, such as C/2014 S3 (PANSTARRS). Twenty-seven Manx comets were found from 2013 to 2017.</p>
</blockquote>

CC BY-SA 4.0
2024-08-12T02:55:30.397Z
2024-08-12T02:55:30.397Z
Nilay Ghosh
<p>An asteroid is within the orbit of Jupiter-a comet may or may not be!<br />
A comet has a coma-an asteroid does not.<br />
Furthermore, the orbits of comets tend to be more eccentric.</p>

CC BY-SA 4.0
2024-08-02T13:10:16.587Z
2024-08-02T13:10:16.587Z
Harrychink
<p>Google's definition of a comet is:</p>

<blockquote>
  <p>a celestial object consisting of a nucleus of ice and dust and, when
  near the sun, a ‘tail’ of gas and dust particles pointing away from
  the sun.</p>
</blockquote>

<p>This doesn't cut it for me. Neither does wikipedia's similar entry.</p>

<p>It pertains to the sun, even though comets are present in other parts of the galaxy other than the solar system and probably other galaxies.</p>

<p>Whats more dwarf planet can be classified as follows:</p>

<pre><code> * orbits a host star
 * rounded by its own gravity
 * not massive enough to induce thermonuclear fusion
 * not massive enough to clear its region of debris
</code></pre>

<p>Which pretty much fits the bill of a comet.</p>

<p>Do you think the following is a fair / recognised classification of a comet:</p>

<pre><code>Comet:
* not rounded by its own gravity
* not massive enough to induce thermonuclear fusion
* not massive enough to clear its region of debris
* composition of ice and dust
</code></pre>

<p>But then that's pretty similar to an asteroid:</p>

<pre><code>Asteroid:
* not rounded by its own gravity
* not massive enough to induce thermonuclear fusion
* not massive enough to clear its region of debris
</code></pre>

<p>However, this means if an asteroid is comprised of ice and dust, it becomes a comet?</p>

<p>Or are asteroid <strong>never</strong> comprised of ice and dust? Does my asteroid classification need beefing up, regarding an asteroid's composition?</p>

<p><strong>I'm feeling the comet and the asteroid both need some classification pertaining to their orbit as well? Though thats tricky because only some comets and asteroid, so they're similar in that regard as well! Maybe more details on each objsts composition is needed, like I say...</strong></p>

CC BY-SA 4.0
2024-08-02T15:29:01.893Z
If you search around, you'll find some comets are now asteroids, since they have lost most of their ice. [I don't have any specific examples on hand though].
Greg Miller
CC BY-SA 4.0
2024-08-12T02:51:23.930Z
@GregMiller https://en.wikipedia.org/wiki/Extinct_comet
Nilay Ghosh
CC BY-SA 3.0
2014-07-30T14:36:03.903Z
Cross-posted to http://physics.stackexchange.com/q/127181/2451
Qmechanic
<asteroids><comets><classification>
Classification of a Comet
Starkers
# Classification of a Comet

(Asked by: username_0 on 2014-07-18)

Google's definition of a comet is:

a celestial object consisting of a nucleus of ice and dust and, when
  near the sun, a ‘tail’ of gas and dust particles pointing away from
  the sun.

This doesn't cut it for me. Neither does wikipedia's similar entry.
It pertains to the sun, even though comets are present in other parts of the galaxy other than the solar system and probably other galaxies.
Whats more dwarf planet can be classified as follows:
 * orbits a host star
 * rounded by its own gravity
 * not massive enough to induce thermonuclear fusion
 * not massive enough to clear its region of debris

Which pretty much fits the bill of a comet.
Do you think the following is a fair / recognised classification of a comet:
Comet:
* not rounded by its own gravity
* not massive enough to induce thermonuclear fusion
* not massive enough to clear its region of debris
* composition of ice and dust

But then that's pretty similar to an asteroid:
Asteroid:
* not rounded by its own gravity
* not massive enough to induce thermonuclear fusion
* not massive enough to clear its region of debris

However, this means if an asteroid is comprised of ice and dust, it becomes a comet?
Or are asteroid never comprised of ice and dust? Does my asteroid classification need beefing up, regarding an asteroid's composition?
I'm feeling the comet and the asteroid both need some classification pertaining to their orbit as well? Though thats tricky because only some comets and asteroid, so they're similar in that regard as well! Maybe more details on each objsts composition is needed, like I say...

**Tags:** asteroids, comets, classification

> **Comments:**
> **username_3**: Cross-posted to http://physics.stackexchange.com/q/127181/2451  
> **username_1**: If you search around, you'll find some comets are now asteroids, since they have lost most of their ice. [I don't have any specific examples on hand though].  
> **username_2**: @GregMiller https://en.wikipedia.org/wiki/Extinct_comet  

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## 3 answers

### Answer by username_4 on 2014-10-11. Score: 2

You've answered your own question there, the difference between the two is that asteroids are rock whereas comets are made up of ice and dust. An asteroid doesn't heat up when it gets close to the Sun and doesn't produce a tail. Comets can orbit the Sun or any star in a long elliptical (Comet West) or short elliptical (Comet Encke 3.3 Years) period whereas asteroids are found in the Asteroid Belt between Mars and Jupiter and in the Kuiper Belt. Sedna is a long period asteroid further out any other object in the solar system but it is still an asteroid according to what we know. <https://www.universeguide.com/fact/comets> <https://www.universeguide.com/fact/asteroids>


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### Answer by username_2 on 2024-08-12. Score: 0

Although the difference between asteroid and comets is quite distinct, there are examples which blurs this line. From [Comets (Wikipedia)](https://en.wikipedia.org/wiki/Comet):

> [Extinct comets](https://en.wikipedia.org/wiki/Extinct_comet) that have passed close to the Sun many times have lost nearly all of their volatile ices and dust and may come to resemble small asteroids. Asteroids are thought to have a different origin from comets, having formed inside the orbit of Jupiter rather than in the outer Solar System. However, In the early 21st century, the discovery of some minor bodies with long-period comet orbits, but characteristics of inner solar system asteroids, were called [Manx comets](https://en.wikipedia.org/wiki/Manx_comet). They are still classified as comets, such as C/2014 S3 (PANSTARRS). Twenty-seven Manx comets were found from 2013 to 2017.


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### Answer by username_5 on 2024-08-02. Score: 0

An asteroid is within the orbit of Jupiter-a comet may or may not be!  
A comet has a coma-an asteroid does not.  
Furthermore, the orbits of comets tend to be more eccentric.


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