what are asteroids?

Answer 1

Things in space orbiting the Sun that are smaller than planets but bigger than meteoroids. Say between 50 feet and 500 miles wide or so.

Answer 2

Asteroids are big rocks floating in space. Since they are big rocks and not little stars, it would be better to call them planetoids, but some doofus astronomer a long time ago used the word asteroid, and now we're stuck with the word.

Some contain much metal, while others are stony or carbonaceous. The ones furthest from the sun are mostly iceballs, and not just water ice, but also frozen methane.

Most of the known asteroids orbit between Mars and Jupiter.

Some (called Trojans) occupy Lagrangian positions of gravitational stability ahead and behind the larger planets in their orbits around the sun.

Some others orbit between Saturn and Uranus (e.g. Chiron).

Some icy asteroids orbit beyond Neptune's orbit in what is called the Oort cloud. When Oort asteroids come into the inner solar system on orbits of long period and high eccentricity, the solar radiation causes them to lose mass which spreads into a long tail: we call them comets.

A few asteroids have relatively short periods and high eccentricities. At their farthest, they might go past Mars. But when they are closest to the sun, they might be inward of Venus. Some of these can pass fairly close to Earth's orbit. A very few can pass very, very, very close to Earth's orbit.

One of them is an asteroid known as 2001-VK5. It's orbital elements are:

a= 1.26941706 AU
e= 0.514147527
i= 19.4427492 degrees
L= 54.4098601 degrees
w = 263.7440718 degrees

Earth's orbital elements are:

a= 1.00000011 AU
e= 0.016709
i= 0
L= 0
w= 102.9404 degrees

If you study the orbits appropriately, you can tell that they have a nearest approach distance of 38200 kilometers. It wouldn't take much of a perturbation to make the asteroid hit us smack on.

Here's an asteroid whose orbit might already be positioned for a direct hit on Earth: 1997-XR2.

a= 1.07668043 AU
e= 0.201052295
i= 7.1714542 degrees
L= 250.9056653 degrees
w= 84.6018693 degrees

Minimum distance: 8150 kilometers.

Here's another one! It's called 2000-QK130.

a= 1.18085328 AU
e= 0.261868550
i= 4.7192870 degrees
L= 174.0509693 degrees
w= 66.2423441 degrees

Minimum distance: 28550 kilometers.

Wait! We have another! This one's name is 2001-XU.

a= 2.56044096 AU
e= 0.837278668
i= 19.0241440 degrees
L= 261.6342256 degrees
w= 285.4251983 degrees

Minimum distance: 17900 kilometers.

Where do they all come from? This one's called 1999-AN10.

a= 1.45870695 AU
e= 0.562190451
i= 39.9322895 degrees
L= 314.5069337 degrees
w= 268.2945012 degrees

Minimum distance: 54300 kilometers.

So, as you can see, there's some danger of a significant asteroid hit in the future.

Answer 3

Yes, most asteroids are found in the Asteroid Belt between Mars and Jupiter. However, there are billions asteroids orbiting in the vicinity of Earth's orbit that have no connection with the mainstream asteroids.

Many may have been knocked out of the asteroid belt, by planetary gravitational disturbances or by impacts between them, but just as many seem to have not come from that source.

It is interesting that when a comet like Halley takes up a regular orbit around the sun, every time it passes close to the sun in its elongated orbit (every 76 years for Halley) the sun's power drives off more and more of its volatile gases and dust (that's what makes the tail). After many passes of the sun, when all the gases and dust have been driven off, the comet is just a collection of rocks, indistinguishable from asteroids.

Therefore, many asteroids that are nothing to do with the asteroid belt, are obviously leftovers from spent comets.

Answer 4

An asteroid is a predominantly rocky body that orbits around its star. In our solar system, asteroids are the best known class of minor planet (or planetoid). They are much smaller than even the small major planets such as Mercury or Mars. The vast majority of the asteroids are found within the main asteroid belt, with elliptical orbits between those of Mars and Jupiter. It is thought that asteroids are remnants of the protoplanetary disc, and in this region the incorporation of protoplanetary remnants into the planets was prevented by large gravitational perturbations induced by Jupiter during the formative period of the solar system. Some asteroids have moons.

Answer 5

Big Chunks of rocks floating around in space. Most of the Asteroids in are Solar System are located between a big belt between Jupiter and Mars called the asteroid belt. Sometime these rocks crash in to each other and it sends it out in space which can be a hazard to Earth

Answer 6

Asteroids are minor planets orbiting the sun between Mars and Jupiter. See http://en.wikipedia.org/wiki/Asteroids

Answer 7

asteroids are mainly rocky masses that float in space. they could be the remains of some planetary activity or they could be masses left out during the formation of any heavenly body. depending upon the source, they keep on moving throughout the space and may end up colliding with some other heavenly body.

Answer 8

large chunks of rock not big enough to be planets and separate from any planetary system, with their own solar orbit.

Answer 9

rocks floating in space, some of which crash into the earth.

Answer 10

My dad has them, but he is getting an operation to get rid of them.