Formerly, it was known in astronomy that the Solar System has nine planets namely Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. But around the late 1990s, it was discovered and acknowledged that Pluto is relatively small to be considered a planet. Thus, declaring it as a dwarf planet and reducing the number of planets into eight. The first four innermost planets Mercury, Venus, Earth and Mars are called terrestrial planets because of their rocky surfaces and formation.
The other four planets Jupiter, Saturn, Uranus and Neptune are called Jovian or Jupiter-like planets because they are massively bigger than the terrestrial planets. They also have a gaseous surface that mostly contains hydrogen and helium. Jupiter and Saturn are also called gas giants because they are more dominated by gas while Uranus and Neptune are called ice giants because they are dominated by ice.
Mercury is the planet that is closest to the Sun. It is only a bit bigger than the Earth’s moon and orbit the Sun in a quick 88 days. Because it has no atmosphere to absorb meteor effects, its surface is covered with craters and has a gray to orange color. Venus is the second planet from the Sun and has the hottest surface among the nine planets. Its atmosphere is massively composed of carbon dioxide and sulphuric acid making its atmosphere appear to be brownish-yellow in color. Earth is the third planet from the Sun. Its surface has liquid water, nitrogen, oxygen and active plate and can maintain life. It has one moon and rotates on its axis every 24 hours and orbits the Sun every 365 days. Mars is the fourth planet from the Sun. It has a reddish and thin atmosphere because of the dust and iron oxide. It has a very cold surface that comprises of craters, volcanoes, mountains and large canyons. Jupiter is the largest planet and the fifth from the Sun. It has a surface that is primarily made up of gases like hydrogen and helium. It has a strong magnetic field and about 63 satellites.
Saturn is the sixth planet from the Sun. Its surface is also composed of mostly gases. It is well-known because of its three rings. Uranus is the seventh planet from the Sun. It has an atmosphere that consists mainly of Methane giving it a blue-green color. Neptune is the eighth planet from the Sun. It is known for its strong winds and has a very cold and rocky atmosphere.