According to NASA, Mercury is considered a terrestrial planet, meaning it has a core, mantle and crust, much like Earth. Mercury's atmosphere contains oxygen, sodium, hydrogen, helium and potassium. More »

There is not much known about Mercury or its surface, except that it is similar to the moon in appearance and its composition consists of primarily molecular oxygen, sodium and hydrogen. There are also small amounts of h... More »

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

Scientists believe phytoplankton in the Earth's oceans produce between 50 and 85 percent of the planet's oxygen. The exact figure is difficult to calculate because scientists do not know how much phytoplankton exists on ... More »

Scientists have hypothesized and made predictions about the cause of the Earth's magnetic fields, and the prevailing theory is that the Earth's magnetism originates from the planet's center, or core. Because scientists d... More » Science Physics

Mercury is the smallest planet in the solar system, and it is only slightly larger than Earth's moon. The closest planet to the sun, Mercury takes just 88 Earth days to complete a single orbit. More »

The Earth's core consists primarily of hot and solid iron and nickel. It is the innermost layer of the Earth and has a temperature of up to 13,000 degrees Fahrenheit. More » Science Earth Science Layers of the Earth