Universe Today : Mars at its Closest Approach

Written by Fraser Cain

Okay, now you can tell your friends and family that Mars is making its closest approach, and not August like that annual hoax email that goes around. This image of Mars, taken by the Hubble Space Telescope, was captured when the planet was only 88 million km (55 million miles) away from Earth. Their closest point occurs on December 18th at 1145 UTC (6:45 p.m. EST).

This close encounter between the Earth and Mars happens every 26 months. That's because Earth makes more than two orbits for every one Martian trip around the Sun. As the Earth catches up with Mars in orbit, the planet brightens in our skies until it becomes one of the brightest objects we can see.

Since both Earth and Mars have elliptical orbits, the point of their closest approach changes from year to year. Back in 2003, when that closest approach between Earth and Mars actually happened, the two planets were 32 million km closer (20 million miles) than today. (Of course, Mars never looked as large as the Moon in the sky, it was always just a bright red star.)

The image attached to this story was made up of a series of photographs captured by Hubble over the last 36 hours. They were then stitched together on computer to make up this composite photograph.

The large triangular dark shape on Mars is Syrtis Major, and the region on the left is called Sinus Meridani. That's roughly where NASA's Opportunity rover is currently rolling across the Martian landscape.

When Hubble took this photograph, the planet was largely free of the dust storms that plagued the Mars rovers earlier this year. Although, you can see clouds near the northern and southern poles.

Original Source: Hubble News Release