Asteroid

How long is it, and how far is it from the sun?

What follows is a "Reader’s Digest"-style summary of a very large topic, Hopefully, it prompts some more questions and gives you some leads as to what to follow up.

The first four asteroids to be discovered were: 1 Ceres in 1801, 2 Pallas in 1802, 3 Juno in 1804 and 4 Vesta in 1807. They were given the status of planets, a status they kept for over 50 years. But as the numbers started to burgeon after 5 Astraea was found in 1845, they were removed from the planetary club and regarded as asterods thereafter. By 1868 there were 107 known asteroids and by the dawn of the 20th Century in 1900 the total had reached 452,

All the initial discoveries were in the (main) asteroid belt, between Mars (1.5 AU from the Sun) and Jupiter (5 AU from the Sun). (1 AU = 93 million miles).

There are at the latest count 342,536 asteroids and we are finding them at the rate of 5,000 or so a month. There are estimated to be somewhere between 1.1 amd 1.9 million asteroids of size 1 kilometre or greater in all.

The orbits of about one-third of these are sufficietly well-known and charted that they have been given a Minor Planet Centre catalogue number, and about 13,000 of those have been given names.

Most of the names are feminine ones and they were usually the names of nymphs or goddesses in Greek and Roman mythology. But these began to run out rapidly, even after using up the names given to moons of planets a second time (e,g, the 4 Galilean moons of Jupiter have their counterparts: 52 Europa, 85 Io, 204 Kallisto and 1036 Ganymed in the asteroid belt),

Some asteroids have moons (243 Ida was the first one to have a moon discovered orbiting it, which was named Dactyl). 87 Sylvia has two moons, named Romulus and Remus.

Some asteroids are double ones e.g. 90 Antiope and the Trojan pair 617 Patroclus and Menoetius, orbiting at Jupiter’s L5 LaGrangian point are a binary pair too.

As more and more asteroids were discovered, they started to be found in other places apart from the main belt inside Jupiter’s orbit.

There are asteroids that come inside the orbit of Mars and some of these come near the Earth and are known as Near Earth Objects (NEO). The international co-operation project Spaceguard keeps an eye on any NEOs which may perhaps threaten to collide with the Earth.

There are about 4000 such Potentially Hazardous Objects. They are grouped as Amors, Atens and Apollo asteroids, the last group go nearest to the Sun.

The first NEO to be discovered was 433 Eros, 4179 Toutatis came uncomfortably close in 2004 and 99942 Apophis looked set for a collision course in 2029, but the chances of that are now regarded as slim (1 in 43000),

There are asteroids inside the orbit of Neptune which are collectively known as Centaurs. The IAU insists these have to be named after individual Centaurs from Greek and Roman mythology (the Centaurs were half-man and half-horse). The best-known of these is 2060 Chiron, which is also classed as a comet.

And finaljy, asteroids are classified by spectral type: In 1975, an asteroid taxonomic system was developed by Clark R. Chapman, David Morrison, and Ben Zellner. The classifications reflect the composition of the asteroid’s surface material. Originally (it has since got more complicated), they classified only three types of asteroids:

C-type asteroids – carbonaceous, 75% of known asteroids
S-type asteroids – silicaceous, 17% of known asteroids
M-type asteroids – metallic, most of the remaining asteroids

(Carbon and silicon are the 6th and 7th most abundant elements in the yniverse.)

In the last 2 years, using the Spitzer Space Telescope, we have found asteroid belts around two nearby stars Tau Ceti (11 light years away_and HD 69830 (41 light years away), The former is about ten times as massive as our own asteroid belt, and the latter about 25 times as massive as our own asteroid belt.

The latter has three Neptune-sized exoplanets as well, all within the habitable zone. So it seems that a belt of minor planets is not unique to the solar system. And if we have a million or more asteroids, just how many asteroids will these more massive belts prove to contain!? And what size will they be?

The universe was perfectly ordered and neat. Then Adam ate a fruit and planets started to collide, chunks of ice and rock started hurtling through space and smashing into planets, dust rings formed around saturn, black holes started sucking up planets…..

All that from 1 bite of fruit, right?

No they were doing that before he ate the fruit.

Probably it is the debris from another planet-turned-evil. God destroyed that planet with an explosion. One day Earth will be nothing but another asteroid belt.

As others have said, there’s actually quite a lot of space between the asteroids – it is not like they show in the movies! In fact, when the Galileo space craft when to Jupiter, they actually had to adjust its trajectory a little so that it could get close to an asteroid and take some pictures!

It goes from about 2AU to about 3.25AU.

The asteroid belt is a region of the solar system falling roughly between the planets Mars and Jupiter where the greatest concentration of asteroid orbits can be found.