Questions About Comets (formerly Can Someone explain.....)

[pretender]

Can someone explain how Comets come to be and why they don't get destroyed sooner also how they stay in the same orbit, TA .. Are they parts of destroyed planets?????

[SkepticLance]

pretender.

We all need to understand that a lot of what is understood about astronomy is not certain. Comets are interesting and we THINK we understand their origins?????

 

According to latest theory, they originate from way out. Possibly the Kuiper Belt, which is beyond Pluto. A long, long way from the sun. They are lumps of frozen water, gases, and bits of rock and dirt, all mixed together, although their exact make-up may vary. They orbit in circular orbits, and there are millions of them. Normally they keep well away from the sun, or Earth, or any of the major planets.

 

However, every now and then, something (Probably a large mass orbiting the sun at great distance. We now believe there are probably many planets at that great distance, even if we haven't seen them with our telescopes.) passes close to one of these lumps of frozen gas, water, and mud. Its gravity gives the mass a 'kick' and sends it spiralling down towards the sun.

 

As it gets closer to the sun, the increasing temperature starts to evaporate the frozen gases. They are pushed away from the comet by the stream of particles coming from the sun. This forms the comets tail. A comet may pass round the sun just once, and be destroyed, or, like Halleys Comet, pass out and in many times.

[RyanJ]

I will also try to explain how they actually come to be...

 

In the formation of the solar system particles fall together undrr gravity creating clumps, these fall together making bigger clumps and so on until you have something like a planet or the sun. During the formation of the solar system this would have occured - eventually the sun got big enough and hot enough for fussion to occur in its core, when this appened all the remaining dust, gas and small rocks were pushed out by the solar wind to where they are now. The process continued here to some extent too , making them larger still.

 

These can be knocked out of orbit by collisions or by moving close to another large object (some even suspect a black hole passing near by could be resposnsible).

 

The asteroid belt however is unusual because it is suspected to be the remains of a small planet that was pulled appart and stopped from re-forming by Jupiter's huge gravity.

 

Cheers,

 

Ryan Jones

[pretender]

Both of you have been very helpful, thank you, so we say that there orbit can change??? can there mass get a lot bigger???

[RyanJ]

Both of you have been very helpful, thank you, so we say that there orbit can change??? can there mass get a lot bigger???

 

Yes it can change, collisions and influences of other bodies can cause them to shift out of orbit. As with anything, if they pass through an area with lots of dist, gas etc. it will then attract some of that through gravity and its mass will increase.

 

Cheers,

 

Ryan Jones

[RyanJ]

Both of you have been very helpful, thank you, so we say that there orbit can change??? can there mass get a lot bigger???

 

Yes it can change, collisions and influences of other bodies can cause them to shift out of orbit. As with anything, if they pass through an area with lots of dist, gas etc. it will then attract some of that through gravity and its mass will increase.

 

Cheers,

 

Ryan Jones

[pretender]

Sorry to be a pain here. But I have another Question. Is it possible for a comet to slow down and stay in one orbit like a planet????????

[[Tycho?]]

Sorry to be a pain here. But I have another Question. Is it possible for a comet to slow down and stay in one orbit like a planet????????

 

If for example a comet was coming close to a planet, the planet's gravity would have an effect on the comets path. So if the path was altered in a very precise way the result could be a fairly circular orbit around the sun- but much closer than the kuiper belt. Note that there are no circular orbits, they are all elipises, some of which are more circular than others.

[dirtyamerica]

Fortunately, we're somewhat protected by the solar systems "vacuum cleaner"...Jupiter. It collects some object due to it's gravity before it can hit us.

[SkepticLance]

I doubt that a comet would ever achieve a circular, planet-like orbit. The adjustment would be just too precise to happen by chance. However, there are comets that have their orbits changed drastically, even though they stay elliptical.

 

For example : Halleys Comet orbits every 76 years. It must have been drastically altered by the gravity of some other object (probably Jupiter), since the 'natural' orbit of a comet is thousands of years.

 

Incidentally, the asteroid belt was not a small planet. The total mass is way too small to even make up half of Earth's moon. Some astronomers think there should have been a planet in that orbit, but do not know what happened to it!

[RyanJ]

I doubt that a comet would ever achieve a circular' date=' planet-like orbit. The adjustment would be just too precise to happen by chance. However, there are comets that have their orbits changed drastically, even though they stay elliptical.

 

For example : Halleys Comet orbits every 76 years. It must have been drastically altered by the gravity of some other object (probably Jupiter), since the 'natural' orbit of a comet is thousands of years.

 

Incidentally, the asteroid belt was not a small planet. The total mass is way too small to even make up half of Earth's moon. Some astronomers think there should have been a planet in that orbit, but do not know what happened to it![/quote']

 

I agree, very unlikley they would have an orbit anything like that of a normal planet. I believe they spsuect both pluto and the new planet to be captured asteroids... they are still bedating that though, some feel they are to big tobe classed as such.

 

Cheers,

 

Ryan Jones

[Hazel M]

Fortunately, we're somewhat protected by the solar systems "vacuum cleaner"...Jupiter. It collects some object due to it's gravity before it can hit us.

I didn't know this. So, the comet is just "eaten" by Jupiter. I'm thinking that, if Jupiter ever collects enough of those comets, it might become more solid. Maybe build up a core? A wild dream, that is? Is Jupiter hot enough to melt the solids in the comet?

[Mordred]

Actually Jupiter is generally thought to already have a core, though there is some debate on this,or rather there is some debate on the Cores composition. The surface temperature is low enough to freeze water. The first link has some good information the debate is discussed in the second article,(though technical)

 

http://en.wikipedia.org/wiki/Jupiter

 

http://arxiv.org/pdf/astro-ph/0403393v1.pdf

Edited June 21, 2014 by Mordred

[Hazel M]

Thank you, Mordred. I shall check out the references.

[Moontanman]

Actually Jupiter is generally thought to already have a core, though there is some debate on this,or rather there is some debate on the Cores composition. The surface temperature is low enough to freeze water. The first link has some good information the debate is discussed in the second article,(though technical)

 

http://en.wikipedia.org/wiki/Jupiter

 

http://arxiv.org/pdf/astro-ph/0403393v1.pdf

 

 

The surface temperature of Jupiter is low enough to freeze water?

[Mordred]

surface temperature is 165 K which is is roughly -108 degrees Celsius

 

http://nssdc.gsfc.nasa.gov/planetary/factsheet/jupiterfact.html

Edited June 21, 2014 by Mordred

[Airbrush]

.... the surface temperature is low enough to freeze water.

 

 

I suppose you mean the cloud tops are that temperature. The "surface" of Jupiter is a vague notion, it just gets hotter and denser the deeper you penetrate into the atmosphere. Until the gaseous atmosphere gets very hot and dense as a thick fog, then as dense as a liquid, and deeper yet it becomes metalic hydrogen. Could there be a solid core in Jupiter?

 

Pretender, next time create a descriptive title, so people know what the discussion is about. Something like "Questions About Comets".

I doubt that a comet would ever achieve a circular, planet-like orbit. The adjustment would be just too precise to happen by chance. However, there are comets that have their orbits changed drastically, even though they stay elliptical.

 

There are SO MANY comets that even if only a tiny percentage of comets that encounter a strong gravity field, like a planet or another, larger comet or asteroid, will achieve near circular, planet-like orbits, that will result in many comets doing so.

Sorry to be a pain here. But I have another Question. Is it possible for a comet to slow down and stay in one orbit like a planet????????

 

Circular orbits is the natural state of most comets. They orbit the sun in nearly circular, eliptical orbits, in the asteroid belt, the Kuiper Belt, and the Oort Cloud. Only those few comets that get nudged out by interaction with planets or other comets and asteroid, come sailing into the inner solar system on elongated eliptical orbits.

Edited June 22, 2014 by Airbrush

[Mordred]

 

 

I suppose you mean the cloud tops are that temperature. The "surface" of Jupiter is a vague notion, it just gets hotter and denser the deeper you penetrate into the atmosphere. Until the gaseous atmosphere gets very hot and dense as a thick fog, then as dense as a liquid, and deeper yet it becomes metalic hydrogen. Could there be a solid core in Jupiter?

 

yeah your right the value was given at 1 bar. I should have noted that, The surface of the planet is defined as the point where the pressure of the atmosphere is 1 bar, which is equal to the atmospheric pressure at Earth’s surface.

 

Thanks for pointing out that detail I forgot to include (or more accurately forgot altogether lol)

Edited June 22, 2014 by Mordred

[Phi for All]

Pretender, next time create a descriptive title, so people know what the discussion is about. Something like "Questions About Comets".

 

!

Moderator Note

Let's test this advice and see if that gets us some more views and replies, shall we? 655/19 currently.

[Ophiolite]

Mordred's second link in post #13 is way too technical for the level of question posed and manages to obscure the strong consensus view on the formation of gas giants like Jupiter and Saturn. This is that following formation of planetesimals in the protoplanetary disc cores of approximately ten Earth masses are formed. This triggers a runaway growth, attracting large masses of gas from the disc creating a gas giant.

 

Further corrections on earlier posts:

 

1.There are arguably no comets in the asteroid belt - though as Airbursh points out there are so many comets that the odd stray might wind up in the belt. They are common in the Kuiper Belt and make up the hypothetical Oort cloud.

2. Pluto is not a captured asteroid and was never thought to be.

[Ahmedsen]

Hello,

 

Comets had always been an interesting subject for people. People were afraid of them.

 

I found a great explanation of how comets do. Maybe you may be ineterested :