Remnants of Rock and Ice. Asteroids Meteoroids (meteorites, meteor) Comets. Remnants of the Solar Nebula. Small bodies remain virtually unchanged since their formation 4.5 billion years ago They carry history of the Solar system in their compositions , locations , and numbers.
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Remnants of Rock and Ice
Meteoroids (meteorites, meteor)
Asteroid means starlike,a rocky leftover
Meteoroid – small rocky material in spaceMeteor – in the atmosphere(falling star)
Meteorite – any piece of rock than fell to the ground from the sky
Comet meanshair(Greek), an icy leftover
The first asteroid Ceres was discovered by Piazzi on January 1, 1801 in an attempt to find the missing planet between Mars and Jupiter
Ceres has a diameter of half of Pluto
There are more than 100,000 asteroids larger than 1 km in diameter
Early in the history of the Solar system, the belt contained enough planetesimals to form a planet.
Gravitational tugs from Jupiter created the gaps.
Two stable zones along Jupiter’s orbit host two families of asteroids (Trojans).
Meteorites are pieces of rock that fell from the sky.
Seen as fireballs (sometimes with sound)
May cause damage, but most fall into oceans
Meteor showers – result of the Earth’s passing through a comet orbit
Meteors are single pieces of comet dust
25 million meteoroids enter Earth’s atmosphere every day
Meteor showers get their names after constellations from which they appear to radiate
(These occur when earth passes through cloud of debris along a comet’s orbit.)
Primitive meteorites may be either rocky or carbon-rich
Processed meteorites can be removed from the surface of a planet by an impact.
There are meteorites from Moon and Mars found on Earth.
Comets are basically dirty snowballs where ice mixes with rocky dust.
Their mean size is a few kilometers across.
The comet body is called nucleus.
Sublimating ices create coma.
A tail pointing away from the Sun appears.
There are two tails: plasma tail and dust tail.
Comets contain information about the outer solar system
Most of them visit the inner part only once, a few are regular guests
One of the most famous comets is Halley’s comet. It was discovered by Edmund Halley in 1682. Its orbital period is 76 years. The last appearance in 1986.
The larger the impactor, the more rare the impact
In 1908, an unusual explosion occurred in Siberia.
Meteor crater in Arizona formed 50,000 years ago.
A large impact occurred 65 million years ago perhaps caused the dinosaur extinction.
http://campus.pari.edu/sara/arecibo/presentations/fields/294,13,Meteor Trail Recorded During Leonid Meteor Shower, 1998
http://departments.weber.edu/physics/schroeder/astro/lectureslides/356,8,Kuiper Belt objects (other stuff near Pluto)