Asteroids, or planetoids, are rocks larger than meteorites but smaller than planets that orbit around the Sun.

4,467 Questions

What caused the extinction of the dinosaurs?

Scientists have many theories about what caused the extinction of dinosaurs. Below are thoughts on some of the most common theories:

  • Since about 90% of dinosaurs were herbivores (plant eaters), it was thought that when an asteroid hit earth and many tons of dust was thrown into the atmosphere that the result was a "long night" due to the lack of sunlight that was able to reach earth, the plants died out and without a food source, so did the dinosaurs.
  • It could also have been the combination of the Chicxulub asteroid impact event (causing worldwide fires and environmental catastrophe in association with the Deccan Traps volcanic event, which occurred at around the same time, or possibly as a result of, the asteroid impact event.
  • There are many theories that are written throughout history of why the dinosaurs exactly were driven into extinction. Most are meteor impact related. By looking at craters all over the world, scientists can estimate the meteors size, speed and its impacts effect on the local environment. See the related link for more information.
  • Though the large meteorite impact (Chicxulub) figures prominently in a lot of the theories of how the dinosaurs became extinct, the idea of a gamma ray burst has also come up now that we are aware of them and the threat they pose. Additionally, there was an "outburst" of volcanic activity during this period. This extinction event is at the Cretaceous-Tertiary (K-T) boundary.
  • It should also be added that several other large impact events occurred right about the time of Chicxulub, including Silverpit and Boltysh craters, among others. It seems the deck was "stacked against" the dinosaurs, regardless of how you look at it. It is possible that things are "found" to "corroborate" extinction by space rock, but the facts are pretty convincing, even for the skeptic.
  • It was noted but is worth repeating: many of the ideas that represent credible ways that could have triggered the dinosaurs' extinction could have arisen separately and acted in concert to kill off all these creatures. One thing is certain - they're gone. And the demise of the terrible lizards was caused by something dramatic given the relatively narrow window in which they disappeared.
  • The hypothesis that states an asteroid-impact was the sole cause of the extinction is just that - an hypothesis, not a fact. Most paleontologists feel that the asteroid impact was just one of a series of catastrophic events that ultimately wiped out the dinosaurs. There is evidence of a huge meteor strike just off the Yucatan Peninsula, true. And a meteor may well have put a final period to the extinction pulse. But there is also evidence that other factors may have been involved. For one thing, the dinosaurs didn't become extinct all at once. The pulse seems to have taken more than 10-thousand years to complete which makes the asteroid theory implausible as a complete explanation. There is evidence that there was massive volcanic activity also, and a drastic climatic change. The dinosaurs were in decline in number of species long before the K/T extinction was over. Furthermore, some dinosaurs did survive into Laramide time - the birds are still around (admittedly that's begging the issue, but it's not unreasonable to ask how they managed to survive when so many their brethren were killed).
  • Dinosaurs were already fast becoming endangered species before the Chicxulub impact. Increased volcanic activity such as the Deccan Traps in modern day India was slowly killing many species. Between 68 to 60 million years ago 150,000 km2 of igneous rock was deposited in places more than 2 km thick. The bulk of the eruptions occurred about 66 million years ago near modern day Mumbai. These eruptions lasted as little as 33,000 years but the effect on the environment would have been staggering. Dust and debris thrown into the atmosphere along with sulphur dioxide would have cooled the earth. Also many poisonous gases would also have been released. Studies on modern day birds suggest that these poisonous gases not only directly killed dinosaurs but also caused thinning of the shells of their eggs which meant that many would fail to hatch.
  • It has also been suggested that disease killed off the dinosaurs. A very deadly and contagious disease may have circulated among the dinosaurs forcing them to become extinct. Still yet another theory is that the Earth just gradually changed in climate over a long time period and the dinosaurs were not able to adapt to the cooler, dryer climate.
English Language

Do asteroid and steroid have the same etymology?

Yes and no. They both derive from an Indo-European root ster-, but there seem to be three entirely different such roots. The first ster- means stiff or hard, and is the root of steroid. Ster- 2 means spread, and is the root of strew and straw. Ster-3 means star and is the root of star and asteroid.


Where is there an asteroid belt in our galaxy?

The asteroid belt lies between Mars and Jupiter.


How asteroids impacts effect humans?

v People would have no homes and no belongings

v They would need clothing, food and shelter

v Many might be injured

v It would cause riots from people trying to salvage things

v Law enforcement would suffer

v People will most likely be united to survive

v Some people will be greedy

v There would be an even larger pecking order

v People will become more self-reliant and independent

v The weaker will be killed off

The Difference Between

What is the difference between a meteor and a meteorite?

A meteor is a space rock that enters the Earth's atmosphere. A meteorite is the remnant of a meteor that actually reaches the surface (on land or water).

A meteoroid (smaller than an asteroid) is a chunk of rock and/or ice floating about in space (ranging in size from dust to boulders) that can be billions of years old.

A meteoroid becomes a meteor or "shooting star" when it starts to fall through Earth's atmosphere. It heats up by friction and air compression with air molecules, emitting light along its trail to form a fireball, and shrinks as it falls toward Earth's surface because the friction gradually wears it away.

The meteor that is large and durable enough becomes a meteorite when it has hit the Earth's surface. Any chunk or fragment of original meteoroid on or below earth's surface is a meteorite. The largest distinct meteorite discovered was in 1920 in South Africa. It weighed about 50 tons.

Meteor Showers

When the Earth travels through the trails of dust and debris left over from the comets it produces what we know as meteor showers like the Leonids, the Geminids, and Quadrantids. The meteor showers get their names from the radiant (where the originate in the sky). For example the Leonids radiant is from the constellation of Leo.

Meteoroids travel in variety of orbits and speeds around the Sun. They can enter the earth's atmosphere at speeds ranging from 11 km/s to 72 km/s.
There are three words that refer to the same object in different situations: meteoroid, meteor, and meteorite. The question is about two of these, but the answer involves all three:

A meteoroid is a small body traveling through space. Meteoroids are often remnants of comets.

A meteor is a meteoroid that has entered the earth's atmosphere, which makes it heat and light up. Meteors are sometimes called shooting stars, because they look like bright stars streaking across the sky.

A meteorite is a meteor that has reached the earth (that is, it has not completely burned up in its journey through the atmosphere).
A meteor is the streak of light of a space rock falling into the Earth's atmosphere at high speed and glowing to incandescence due to friction and compressive heating.

A meteorite is the remains of a space rock after it has crashed into the Earth. Meteors frequently explode while falling through the atmosphere, or break up when they hit the ground.

The Difference Between

What is the difference between meteor and meteorite?

Astronomers call "shooting stars" meteors. They are small bits of "dust" from space that burn up in the atmosphere. A meteorite is a piece of rock or other material from space that actually lands on Earth.

Newtons Laws of Motion

What keep asteroids moving through space?

the gravity of large masses. the large masses could be other planets or stars or our sun

Their own momentum. other masses only deflect them by changing their momentum.

Dwarf Planet Eris
The Solar System

Where is the asteroid belt located?

The asteroid belt is located between Mars and Jupiter.

Timing Belts and Chains

What is the difference between a commemorative belt and a replica belt?

A Commemorative belt is the same size as the original but its made of plastic. The Replica Belt is also the same size but its made of metal, so its more authentic.

Atmospheric Sciences

Does an asteroid burn up earths atmosphere?

An asteroid doesn't burn up the atmosphere but the atmosphere burns up the asteroid. The asteroid which is moving at a very high speed due to the intense pressure change exerted over it, has a rise in temperature which reaches its igniton temperature and finally it burns out leaving a trial of light behind it.

Planetary Science
Planet Earth

How do you stop planet nibiru approaching planet earth without harming inhabitants of nibiru?

Since Nibiru does not exist, you don't have to do anything.


Is a meteor going to hit earth?

Meteors hit the earth frequently. Shooting stars are space debris that burns up in the atmosphere, but small pieces often make it through.


The asteroid belt is located between the orbits of what two planets?

The asteroid belt is located roughly between the orbits of the planets Mars and Jupiter, about 2.5 to 3 AU (375 to 450 million kilometers) from the sun. It includes the dwarf planet Ceres, the protoplanets Vesta and Pallas, and several other large asteroids (minor planets).

The asteroid belt region is also termed the main belt to distinguish it from other concentrations of minor planets within the solar system, such as the Kuiper belt and scattered disc. The main belt has one or two million large bodies (over 1 km in diameter), but their total mass is only about 4% of the mass of Earth's moon. It also contains millions of smaller rocks and dust particles.

There are also a large number of asteroids that orbit the Sun in various orbits, some of which intersect the orbits of planets (including Earth). However, the solar system is so large that most are thousands of kilometers from each other, and major collisions occur only once every million years or so.
Most of the asteroids within our solar system can be found within the Asteroid Belt. Located between the orbits of Mars and Jupiter, the Asteroid Belt consists of millions of individual asteroids of varying sizes - from a speck of dust to hundreds of kilometers in diameter. The largest object within the belt is a dwarf planet - Ceres - which has a mass of 9.47x1020kg and a diameter of 476.2km.


What is an asteroid?

Asteroids, sometimes called minor planets or planetoids, are small rocky bodies in orbit around the Sun, especially in the inner Solar System; they are smaller than planets but larger than meteoroids. The term "asteroid" has historically been applied primarily to minor planets of the inner Solar System, as the outer Solar System was poorly known when it came into common usage.

Most known asteroids are found in the Main Belt between Mars and Jupiter, or in the Kuiper Belt past the orbit of Neptune. But there are thousands that orbit at least as close to the Sun as Earth. The vast majority of asteroids are smaller than 1 kilometer in diameter. The largest asteroid in the Main Belt is Ceres, which has been designated a dwarf planet.

The distinction between asteroids and comets is made on visual appearance: comets show a perceptible lighted envelope or aura while asteroids do not. This is caused by the release of volatile substances, mostly frozen gases, from the comets' interiors.

Asteroids are rocky fragments left over from the formation of the solar system (about 4.6 billion years ago!). They can be found orbiting the sun in an area between Mars and Jupiter called the "Asteroid Belt". This asteroid belt, or "main belt" contains probably millions of asteroids.

Asteroids get their name from the Greek word that means "star-like", a misnomer now considering today's scientific classifications made from our new space data. Asteroids are actually more appropriately referred to by astronomers and other scientists as "minor planets" or "planetoids" (which means "planet-like").

Some facts about asteroids:

  • Asteroids are celestial bodies/objects that are in the solar system.
  • An asteroid orbits the planets and sun and moon as a "mid-sized celestial object" - from 10 meters to 1000 km in diameter.
  • They are a mixture of stone, heavy and light elements, and possibly gasses (in solid, liquid, frozen, or plasma states/organic/inorganic).
  • One will often have meteoroid clouds nearby or trailing them (may be considered as comets).
  • It may be moving either in orbit around another celestial object or floating or traveling on its own accord.
  • They are also called minor planets, planetoids, centaurs
  • Classifications of smaller asteroids are:
C-type, carbonaceous

S-type, siliceous

M-type, metallic

There are many good reference sources on the Internet about asteroids. Try some of the web sites listed in the related links section for this question below.


Is it possible to destroy an asteroid?

It is possible in theory, but one has to wonder why.

Asteroids hit Earth every year, most, if not all disintegrate in the atmosphere. Only a few reach the surface.

If it's large enough and on a collision with Earth or the Moon or another planet?

What are the objectives: To alter the course or to obliterate it.

To attempt to obliterate an asteroid is futile, you'd just end up with billions of smaller asteroids and meteoroids spreading all over the place like a shotgun blast, In all essence, you could actually send a piece of it somewhere, where it was not destined to go in the first place. Just like a large dog, best to leave it where it is.

Heading for Earth: Part of the NEO (Near Earth Object) surveillance is to detect objects that "could" impact with the Earth. Luckily, no objects have been found "so far" - the only object on the "watch list" is 99942 Apophis which was destined to impact Earth in 2009 but didn't (Hence how this is now being written). It's now predicted to impact in 2036. Phew.

Trying to destroy an asteroid is not a simple fact. One can't just send Bruce Willis up with a few nuclear bombs, and hope for the best - or worst. Hollywood would make us believe that it would happen, but what truth has come out of Hollywood?

We can't just send up a couple of nuclear missiles. 1) We don't have a rocket with sufficient payload to deliver such a weapon. 2) It wouldn't do any good, a nuclear bomb has to have something to "push" against to deliver the "force". In space there is nothing to push against. The only way to use nuclear weapons is to imbed them into the asteroid - call up Bruce Willis. See above.

The preferred option is to "nudge" the asteroid away from it's predetermined path. Using rockets like large dumpster trucks, it's possible, given enough time and resources, to alter the trajectory of the asteroid away from Earth.

However, this posses additional problems. By altering the trajectory, the asteroid may miss Earth, this time, but might cause a cacophony of additional problems. It may swing by Jupiter dislodging more asteroids from the Asteroid Belt or move into a more deadly orbit that cannot be altered.

At the moment we do not have the resources or the equipment for any of these options.

If an asteroid is detected on a collision course with Earth tomorrow, we have no alternative but to put our heads between our legs and ...........

The Solar System

Where is the asteroid belt?

The main Asteroid Belt in the solar system is located between the orbits of Mars and Jupiter. It contains many millions of rocky objects and dust particles, and the dwarf planet Ceres (formerly considered simply the largest of the asteroids).

However, there are other asteroids that orbit outside the main belt; some of them come in as close as Venus, and out as far as Neptune. Beyond Neptune, the Kuiper Belt contains many more icy objects, including three dwarf planets.


Is there a asteroid coming to earth?

Yes, but there is no evidence as to when or how large it will be.

Ans is

NASA has confirmed that the 60 meter (or 197 feet) asteroid, which was spotted by Spanish stargazers in February this year,


What is the smallest type of asteroid called?

Anything smaller than 50 meters on its longest axis is generally referred to as a meteoroid. This isn't a universally accepted terminology (yet) but it is a widely accepted convention. As far as I know it is the only naming convention for the bottom end of the size spectrum.

The Moon

Will elenin hit Earth?

Comet Elenin (C/2010 X1) was first discovered on December 10th by Leonid Elenin. I have not yet seen detailed descriptions of its orbit, but early calculations indicate that it will probably be visible to the naked eye in late August or early September 2011.

It's not going to hit the Earth; it MAY come within about 0.4 AU but not much closer.

That is not proven as we do not know the size of the meteor as NASA have not give us the measurements. NASA have also given a warning to all their employees to make sure their families are safe on October the 16th.


What is the surface temperature of an asteroid?

A typical asteroid is -100 F or -73 C.

The Difference Between

What is the difference between asteroids and comets?

The main difference between asteroids and comets is what they are made of. Asteroids are made of metals and rocky material, while comets are made up of ice, dust and some rocky material. Both asteroids and comets were formed early in the history of the solar system, about 4.5 billion years ago. Asteroids formed much closer to the Sun, where it was too warm for ices to remain solid. Comets formed farther from the Sun where ices would not melt. Comets which approach the Sun lose material with each orbit because some of their ice melts and vaporizes to form a tail.

An asteroid is a small, inactive body, made up of rock, carbon or metal, that orbits the Sun.

A comet is also a small, but sometimes active object, made of dirt and ice. Comets are able to be seen by their characteristic tails as they become affected by the heat of the Sun. The tail of a comet is pushed away from the Sun. It does not necessarily trail behind it.

Comets follow highly elliptical orbits, approaching the inner solar system and then retreating to a considerable distance from the Sun. If they stayed close in to the Sun, all the ice would vaporize, and they would cease to be comets. Most asteroids tend to have more nearly circular orbits, although some develop more elongated orbits as a result of gravitational interactions with the planets or other asteroids.

Asteroids have diameters anywhere from a few meters to a few hundred kilometers. Only about 200 asteroids have diameters exceeding 100 kilometers. Most rotate on their axes every 5 to 20 hours. Most asteroids in the solar system are located in the 'asteroid belt', where they orbit the sun in the space between the orbits of Mars and Jupiter. Some smaller asteroids may orbit larger asteroids as satellites. Asteroids are different from planets and moons mainly because of their much smaller size, and irregular shapes.

Planetary Science

What is the composition of an asteroid belt?


Planet Venus

Is Venus inside or outside the asteroid belt?


Planetary Science

What is the asteroid belt's length of day?

The asteroid belt is made up of many thousands of small rocks, each with their own unique rotational characteristics. Some may spin quite fast, while others may barely spin at all. So an apparent solar day for an individual asteroid will vary, depending on which one is being studied.


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