Earth’s Moon is the fifth largest of the 200+ moons orbiting planets in our solar system.
Earth’s only natural satellite is simply called “the Moon” because people didn’t know other moons existed until Galileo Galilei discovered four moons orbiting Jupiter in 1610.
With a radius of about 1,080 miles (1,740 kilometers), the Moon is less than a third of the width of Earth. If Earth were the size of a nickel, the Moon would be about as big as a coffee bean.
The Moon is an average of 238,855 miles (384,400 kilometers) away. That means 30 Earth-sized planets could fit in between Earth and the Moon.
The Moon is slowly moving away from Earth, getting about an inch farther away each year.
Earth’s Moon has a core, mantle, and crust.
The Moon’s core is proportionally smaller than other terrestrial bodies’ cores. The solid, iron-rich inner core is 149 miles (240 kilometers) in radius. It is surrounded by a liquid iron shell 56 miles (90 kilometers) thick. A partially molten layer with a thickness of 93 miles (150 kilometers) surrounds the iron core.
The mantle extends from the top of the partially molten layer to the bottom of the Moon’s crust. It is most likely made of minerals like olivine and pyroxene, which are made up of magnesium, iron, silicon, and oxygen atoms.
The crust has a thickness of about 43 miles (70 kilometers) on the Moon’s near-side hemisphere and 93 miles (150 kilometers) on the far-side. It is made of oxygen, silicon, magnesium, iron, calcium, and aluminum, with small amounts of titanium, uranium, thorium, potassium, and hydrogen.
Long ago the Moon had active volcanoes, but today they are all dormant and have not erupted for millions of years.
Credit : NASA Science
Picture Credit : Google
