Distance from Earth to Mars
Written by Fraser Cain
Both Earth and Mars travel around the Sun in elliptical orbits. So to figure out the distance between the two planets, you have to imagine where they can be in various points of their orbits.
At their closest point, the three objects are in a straight line: Sun, Earth, Mars. And then at their most distant point, Earth and Mars are on opposite sides of the Sun.
It gets more complicated than this; however, because both Earth and Mars travel in elliptical orbits around the Sun. Their orbits can bring them close or more distant to each other depending on what point of their orbit they're on.
The closest theoretical point Earth and Mars can be is when Earth is at its aphelion (or most distant point in its orbit), and Mars is at its closest. At this point, the two planets are separated by only 54.6 million km.
This is theoretical though, and would take millions of years to get the perfect point where the planets lined up. The closest point in recent memory was back in 2003, when Earth and Mars were separated by only 55 million km.
The furthest theoretical point is when Earth and Mars are on opposite sides of the Sun, and both at their furthest point from the Sun. At this point, the two planets can be 401 million km.
Because of the wide ranging distant between Earth and Mars, you can see why the planet is something very bright in the sky, and other times hard to find at all.
This website lists every Mars opposition time, from recent past all the way in the far future. You can also use NASA's Solar System Simulator to see the current position of any object in the Solar System.
Have you heard the hoax that Mars is going to be as large as the Moon in the sky? Yeah, that's not ever going to happen.
Finally, if you'd like to learn more about Mars in general, we have done several podcast episodes about Mars at Astronomy Cast. Episode 52: Mars. We have also done an episode explaining distances, Episode 10: Measuring Distance in the Universe.
Filed under: Astronomy
