What Is the Distance From the Sun to Mercury?

By Chris Deziel
Temperature variations of about 611 degrees Celsius (1,100 degrees Fahrenheit) exist on Mercury.

Mercury is the closest planet to the sun, and on average, it is 57 million kilometers (35 million miles) away. That's less than 40 percent of the distance from Earth to the sun. Mercury's orbit is elliptical, though, and its distance from the sun varies by 24 million kilometers (15 million miles).

Elliptical Orbit

Unlike Earth, which circles the sun in a nearly circular orbit, Mercury orbits in an ellipse. The eccentricity of Mercury's orbit, which is a measure of how much it differs from a circular orbit, is 0.2056. That's more than 10 times greater than the eccentricity of Earth's orbit, which is 0.0167. In fact, it's the most eccentric orbit of any of the eight planets in the solar system.

Nearest and Farthest Distances

Unlike a circle, an ellipse doesn't have a center; instead, it has two foci, and in the case of Mercury's orbit, the sun occupies one of them. When Mercury is closest to the sun, it is only 46 million kilometers (29 million miles) distant, but when the planet is rounding the opposite focus of its orbit, it is 70 million kilometers (43 million miles) away from the sun. Because Mercury's poles aren't tilted relative to its orbit, temperature differences caused by its changing distance to the sun are the closest the planet has to experiencing seasons.

About the Author

A love of fundamental mysteries led Chris Deziel to obtain a bachelor's degree in physics and a master's degree in humanities. A prolific carpenter, home renovator and furniture restorer, Deziel has been active in the building and home design trades since 1975. As a landscape builder, he helped establish two gardening companies.