Meteroids, Meteors, and Meteorites

        

Meteoroids are found in outer space.  They float around randomly, and with no specific originating place.
Meteors are meteoroids that have entered Earth's atmosphere.
Meteorites are meteors that have managed to not burn up, and hit Earth's surface.  The largest meteorite weighs 60 tons, hit Earth 80,000 years ago, and is in Namibia, Africa.  There are 3 different classifications for meteors.Stoney, which is made up of silicates, iron, which is made of iron and nickel, and stoney-iron, which is made of all the 3 elements.  When multiple meteoroids enter Earth's atmosphere allat once, it is called a meteor shower.

Comets

        Comets are loose collections of ice, dust, and rock particles, that have very long, narrow ellipses.  The comet has two tails, the gas tail (on top) and the dust tail (on bottom).  The brightest part of a comet is the comet's head, which is made of the nucleus and the coma.  The coma is only there when sublimation occurs as the comet gets close enough to the sun.  Gas and dust boil off the nucleus creating a fuzzy outer layer, called the coma.  The nucleus is like the inside of a comet and is made of ice and dust.  The Greek interpretation of comet means long-haired star.  Each of the comet's tails can e more than a mile long.  Comets are classified into two groups, short-term comets, and long-term comets.  To be classified into the short-term comet group, a comet's period of revolution had to be less than 200 years, and to be a long-term comet, a comet's period of revolution had to be more than 200 years.  The most famous comet, Halley's comet is a short-term comet.  It's period of revolution is 76 years.  Since it's last visit was in 1986, it will visit again in 2062.  Hale Bopp is a long-term comet.  Astronomers estimate it's period of revolution to be around 4000 years.  All comets originate in the Oort cloud or the Kuiper belt (see my post on the solar system).  The sizes of a comet vary-they can be as big as a mountain.

Asteroids

Asteroids are rocky objects revolving around the sun that are too small and too numerous to be called planets.  They are sometimes called planetoids or mini-planets.  Most asteroids are found in the asteroid belt, but can also be found almost anywhere else.   Recently there has been the discovery of Chariklo, an asteroid with 2 rings and was originally in the Kuiper Belt.  It is 155 miles across.

  There are different classifications of asteroids.  The C-type (short for carbonaceous) makes up 75% of all grouped asteroids.  These asteroids are made mainly of carbon.  The next group is the S-type, which is short for silicaceous, makes up 17% of grouped asteroids.  Asteroids in this group are reflective and are made mainly of silicate, iron, and nickel.  M-type is the name of the next group, which is sort for metallic.  This group makes up 8% of all grouped asteroids and is made mainly of iron and nickel.  Last, but not least (actually, this group contains the least amount of asteroids, so scratch that.) is the rare group (no, I'm serious that's the group's name, rare.) which contains less than 1% of all grouped asteroids, who don't fit into any of the other categories.

  The first four asteroids, Ceres, Pallas, Vesta, and Juno were discovered in 1801-1807.  Ceres is now categorized as a dwarf planet, and is the only dwarf planet in the asteroid belt.  All asteroids are described as potato shaped, odd shaped, or irregularly shaped.  Hundreds of thousands of asteroids have been found.