Minor members of the solar system

Asteroids ar small rocky bodies that have been likened to fast-flying mountains. The largest, Ceres, is about 1000 kilometers in diameter, but most are completely about 1 kilometer across. The smallest angulates are assumed to be no larger than grains of sand. Most asteroids lie between the orbits of Mars and Jupiter. They have orbital periods of three to six years. Some asteroids have very eccentric orbits and give way very close to the sun, and a few larger ones regularly spell close to Earth and the mope.Many of the most recent impact craters on the moon and Earth were probably caused by collisions with asteroids. Many asteroids have irregular shapes. Because of this, wandering(a) geologists first speculated that they might be fragments of a broken planet that one time orbited between Mars and Jupiter. Others have hypothe surfaced that several larger bodies once coexisted in close proximity, and their collisions produced numerous littler ones. The existence of several fa milies of asteroids has been used to turn out this explanation. COMETS Comets are the shining wanderers of the solar form.With their glowing ninnys that may crane 100 million kilometers through space. Most comets reside in the outside fringes of the solar system, far beyond Pluto. For all their apparent size in the sky, comets are actually fairly small objects. When a comet begins its trip piling past the Sun, it is probably a chunk of dirty ice, a diverseness of rock dust and ice a few kilometers across, much smaller than the typical observed asteroid. As it belt alongs towards the Sun, the heat from the Sun evaporates the ice, and the gases thus released sport dust particles outward from the solid body or nucleus.Radiation from the Sun ionizes the released atoms, producing a tail that glows in the sky like a neon star sign the dust particles reflect sunlight and form a nonher, smoother tail. But not all develop a tail that extends for millions of kilometers. The fact tha t the tail of a comet points away from the sun in a slightly curved room led early astronomers to propose that the sun has a repulsive pull back that pushes the particles of the coma away, thus forming the tail. The tails seem white to the eye, but change photography reveals that the ionized gas tail is blue and the dust tail yellow.The small nucleus, the only even almost-permanent part of a comet, is surrounded by the coma or head of the comet, a large, hazy structure organise by the liberated gas and dust. Of the 100 billion comets that may exist, less(prenominal) than 1000 have been observed thus far as they touch on the long Journey down to the heat of the Sun. Halleys is one of the best-known and brightest comets others are the Oort cloud which are comets that appear to be distributed in all directions trom the sun, torming a spherical shell around the solar system. METEOROIDS Often referred to as a shooting star.This streak of light occurs when a meteoroid enters the Ea rths aviation. A meteoroid is a small solid particle that travels through space. Most meteoroids stand up from any one of the following three sources (1) Interplanetary debris that was not gravitationally swept up by the planets during the formation of the solar system (2) Material from the asteroid belt, (3) The solid remains of comets that once traveled near Earths orbit. A few meteoroids are believed to be fragments of the moon, or possibly Mars, that were ejected when an asteroid impacted these bodies.Some meteoroids are as large as steroids. Most, however, are the size of sand grains. Consequently, they vaporize before reaching Earths surface. Those that do enter Earths atmosphere and burn up are called meteors. The light that we see is caused by clangoring between the particle and the air, which produces heat. Occasionally, meteor sightings can reach 60 or more per hour. These displays, called meteor showers, result when earth encounters a swarm of meteoroids travelling in the same direction and at nearly the same speed as Earth. A meteoroid that actually reaches Earths surface is called a meteorite.