Planets

A planet is a celestial body that revolves around a star (in this case the sun) and does not emit its own light, but only reflects the light which is received. Planets revolve around the sun, forming an elliptical path. Because the orbit of planets is elliptical in shape, the planets may be near the sun and may be far from the sun. The nearest point of planets to the sun is called perihelion, while the farthest point of planets from the sun is called aphelion. 

The main planet is divided into several types as follows

1. Mercury: Mercury is the first planet from the sun in the solar system. This planet has a small size and its surface is full of craters, so it looks holey. The surface temperature of mercury at noon reches 4000C, while at night  it reaches  -2000C.
2. Venus: Venus is the second planet from the sun and known as the “twin sister” of the earth because its size is almost the same as the Earth. Venus has avery hot and dry surface. Its surface temperature reaches 4500C  so there is no water or o cean. Venus is often  called East Star, Dawn Star, or Morning Star because sometimes it looks shiny in the East at sunrise. Venus is also often called West  Star, Evening Star, or night Star, because sometimes it appears at sunset in the West.
3. Earth: Earth is the third planet from the sun in the solar system. The earth is made up of several layers, those are earth’s crust, eart mantle, outer core of the earth, and inner core of the earth. Earth is the planet that has the atmosphere and surface temperature that enables life activities on it. If it seen froom the outer space, the earth looks blue.
4. Mars: Mars is the fourth planet from the sun in the solar system. The name of mars comes from  the god of war of roman people mars is also  known as the red planet because it looks reddish in the sky at night.  Mars’s surface is very dry and stony, it consists, among others, of valleys, mountainous, and craters. Mars has the largets and highest mountain in the solar system, that is Olympus Mons wich is 27 km high and 600km in diameter. The average temperature in mars is -600C.
5. Jupiter: Jupiter is the fifth planet from the sun and the largest in the solar system. Jupetr’s diameter is about 143 thousand km or 11 times the earth’s diameter, it means the volume of this planet is 1.300 times large than the volume of erth. Jupiter is made up of dense gases such hydrogen and helium, it also has a solid surface. Jupiter’s surface is covered by a rotating gas cloud. The temperature in the upper part of jupiter’s cloud is 1400
6. Saturn: Saturn is the sixth planet from the sun and the second largets planet after Jupiter. Saturn is different from other planets because Saturn has a ring that consists of a dust and pebbles that is covered by ice. Its surface temperature reaches -1760C.
7. Uranus: Uranus is the seventh planet from the sun and the third largest planet after Jupiter and Saturn. This planet was found by Wiliam Herschel, a British astronomer on March 13th 1781. Uranus has a solid care that is made up of metal and is surrounded by the layers of gas and ice. Its temperature is very cold, around 2140C. Uranus looks navy blue.
8. Neptune: Neptune is the eight planet from the sun. This planet was found in 1844 as a result of the cooperation between Leverier (french), Adams (english), adn Galle (berlin/german). The condition of neptune is similar to uranus so these two planets are calle twin planets. The surface temperature of Neptune reaches -1200.

 

Reference:

Irawan, Etsa Indra dan Sunardi. 2008. Pelajaran IPA-Fisika Bilingual untuk SMP/MTs. Kelas IX. Bandung: CV.Yrama Widya.