Sunday, 11 November 2012

Halley's Comet - P1

Comets are small pieces of ice and dust that orbit around the Sun, but their paths are not like those of the planets. Most comets spend much of their time out of the Solar System, beyond Pluto. However, they can enter new orbits that bring them into the Solar System where they become visible from Earth. The most famous comet is called Halley's comet which returns to the center of the Solar System Every seventy-six years. Halley's comet was last seen in early 1986. It will not be seen again until its return in 2061. Halley was the first astronomer to show that some comets followed orbits that keep returning them to the vicinity of the Sun.

Meteoroids are small pieces of rock or metal floating in outer space. When meteoroids float near to the Earth, they may be drawn into the Earth's atmosphere due to gravity. Meteoroids which enter the Earth's atmosphere are called meteors. Most meteors will burn up when they enter the Earth's atmosphere due to friction. Thus, streaks of light can be seen in the sky at night in the dark. They leave behind fiery tails and are called shooting stars. Meteors which do not burn completely and reach the Earth's surface are called meteorites. Meteorites which fall to the ground will make huge craters. One such crater is found in Arizona, the United State of America. many of the planets and their natural satellites are covered with meteorite craters. However, the Earth does not have many meteorite craters since it is protected by its atmosphere.
Huge craters in Arizona, the United State of America