Mercury's atmosphere is primarily made up of oxygen, potassium, sodium, helium and hydrogen. The atmosphere on Mercury is made up of atoms that are launched from the planet's surface from micrometeoroid impacts and solar... More » Science Astronomy Planets

The planet Venus has a thick, dense atmosphere made up almost entirely of carbon dioxide. Though Venus is farther from the sun than Mercury, its surface is actually hotter because the atmosphere traps the heat like a gia... More » Science Astronomy Planets

No one knows who discovered Mercury, as it was known to ancient civilizations. Despite the fact that it's a very small planet, it can be seen with the naked eye. However, it's believed that the Romans gave the planet the... More » History Inventions

Saturn's atmosphere is made up of about 75 percent hydrogen and 25 percent helium, along with trace amounts of water ice and other gases. Like the other planets in the outer solar system, Saturn is a gas giant that lacks... More »

The atmosphere for the planet Uranus is made up of methane, helium and hydrogen. Uranus is considered unique as it tilts at a 98 degree angle, and when the planet is seen from Earth, it looks like it rotates on its side. More »

As a gas giant, Neptune is primarily made from hydrogen, measured at 80 percent of the atmosphere, with an additional 19 percent composed of helium. The remainder of the planet is mainly composed of small amounts of meth... More » Science Astronomy Planets

Neptune's atmosphere is primarily made up of helium, methane and hydrogen, making it unsuitable for sustaining human life. Because Neptune is a gas giant, it has no surface, which means there is no solid ground to land o... More »