According to, the five planets that are visible from the Earth with an unaided human eye are Mercury, Venus, Mars, Saturn and Jupiter. These planets have been known to astronomers since ancient times. More »

Because Mercury is one of the five visible planets to the naked eye, its original discovery is indeterminable. It was known during prehistoric times and was mentioned in the second millennium B.C. by Sumerians. More » Science Chemistry Atoms & Molecules

Space probes carry instruments into space to make measurements that cannot be made on Earth. Temperature, spectrum, magnetic fields and radiation comprise just a few of the types of phenomena measured. Space probes ride ... More »

The five planets which are visible from Earth, using the naked eye, include Saturn, Jupiter, Mars, Venus and Mercury. Because of difference in their orbits, though, it is rare for all of them to be visible in the night s... More »

The inner planets, Mercury, Venus, Earth and Mars, are made up of silicate rock and heavy metals such as iron and nickel, whereas the outer planets, Jupiter, Saturn, Uranus and Neptune, are made up mostly of gases, accor... More »

The names of the nine planets in the solar system are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. However, astronomers have reclassified Pluto as a dwarf planet. More »

The eight planets of the solar system are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. The four inner planets are terrestrial worlds, while the outer solar system consists of four gas giants sometime... More » Science Astronomy Planets