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0answers
44 views

How do you calculate the radiant for Kreutz Sungrazer comets? where in the sky do I look?

According to wikipedia: All known members of the [Kreutz Sungrazer] group up until 1965 had almost identical orbital inclinations at about 144°, as well as very similar values for the ...
4
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1answer
114 views

Why do comets have tails?

There is no atmosphere for comets to get hot and burn and show tails but they still have tails. Why do they? Edit: Isn't the answer "acceleration"?
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2answers
29 views

Ways to spot a comet or asteroid?

How do we spot a comet or asteroid if it does not emit light or pass infront of an object which emits light? And if such an object would be on a crash course with our planet how early would we be ...
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1answer
65 views

List of all past comet passes and area it was visible?

Is there a database/website which shows all comets which have passed Earth and have been viewed? Is there any country specific viewing database as well? I would like to do a search on the lines of : ...
5
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1answer
150 views

What is the likelihood of a long-period comet impact?

I always see lots of information about asteroid impacts, but very little is said about comet impacts. As I see, a long period comet impact is much more dangerous because a) we wouldn't have time to ...
4
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1answer
84 views

Are comets known to exist in other star systems?

Are comets a feature unique to our Solar System? Or, are comets/cometary clouds detected around discovered/observed extra-solar systems too? If they were detected elsewhere, how do such cometary ...
5
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1answer
120 views

How close does a meteorite have to be in order to be heard by the human ear?

...speaking of Perseid meteor showers...How close would a Perseid meteorite have to be in order to be heard by the human ear? Is it even possible to hear a Perseid meteorite? If they come close ...
8
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1answer
53 views

Why does the debris from comets and former comets hang around so long?

So tonight's Quatrantids shower got me thinking. Why does the debris from comets and former comets hang around so long? Each year the earth sweeps through the region of space that the comet went ...
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2answers
29 views

Which direction before dawn to look for Comet Lovejoy (C/2011 W3)? [closed]

Various websites today are reporting with photos and videos of Comet Lovejoy. However, I can't seem to find a definition of which direction to look for it tomorrow morning. I'm in Christchurch, New ...
10
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1answer
3k views

What are the facts that allow accepting the Oort cloud theory?

I admit without any fact that the Oort cloud (comet reservoir) should exist, and it seems to be accepted by far by the large majority of astronomers. But it is still a theory without any direct ...
6
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2answers
51 views

Why doesn't a close comet like Elenin look like other, famous comets (Hale Bopp, Halley…), which have nice, long trails?

Elenin is a comet that runs very close to the Earth (0.8 times the Earth-Moon separation at its closest point). By naked-eye observation, it doesn't look like the other famous comets (Hale Bopp, ...
7
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4answers
3k views

Comet versus asteroids versus meteors

What are the differences between Comet versus asteroids versus meteors in practical terms?
6
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1answer
76 views

What conditions should an asteroid or comet impact need to meet in order to start an impact winter?

Is there a way to calculate if an impact from a given asteroid (say 5 miles in diameter, solid rock to which we know the mass) would start an impact winter? If yes, I would like to see a real example ...
7
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1answer
164 views

Could two colliding comets near Earth cause devastation?

Let's say two comets crashed into each other. If it was 0.1 AU away from the Earth, would the collision cause mass destruction here, or not affect us at all?
2
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2answers
213 views

Why can't you see meteors, but you can see comets from the moon?

Why can't you see meteors from the moon and why can you see comets?
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1answer
4k views

How does a comet form?

As the title explains, How does a comet form? What are the elements, what is a comet composed of? Why didn't they become part of planets, moons or asteroids?