How far is Mercury from the Sun?

	Mercury is the closest planet to the Sun.
	Mercury is, on average, 35.9 million miles from the Sun.
	Its orbit is not a circle.  It is an ellipse.
	Mercury is  0.38 AU* from the Sun.

How big is Mercury? (What is its diameter?)

	Mercury is only about 1/3 the size of Earth.
	Mercury is the smallest planet in our solar system of eight planets. It is the eighth largest planet.
	Mercury is about the size of our moon.
	Mercury's diameter is 4879 kilometers or 3,032 miles across See a diameter

What does Mercury look like?

	Mercury has craters, smooth areas (plains), hilly areas and long cliffs (scarps).
	Mercury is very hot during the day (800°F) and very cold at night. (-280°F).
	It is made of rock with a dense iron-nickel core.
	It has very little atmosphere.
	Mercury has no moons.
	Mercury is a very old planet.

Why is this planet named Mercury?

	When astronomers of long ago were studying the night sky, it seemed to them that Mercury moved very quickly.  The planet seemed to move quickly because it is the closest planet to the sun and its orbit around the sun is smaller than that of any other planet.
	The planet has been known since at least the time of the Sumerians over 5000 years ago.
	The planet is named after Mercury, the Roman messenger of the gods, because he too traveled very quickly.

Can we see Mercury in the sky at night?

	It can be seen from Earth but it is too close to the sun for us to see it very often. It is seen at dawn and twilight.
	To see if Mercury is visible to us at this time of year, check the Sky Maps.

*One AU is the distance from the center of the Earth to the center of the Sun.

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