'Peeping Tom' Hubble Spies Mars' Full Frontal

The Hubble Space Telescope has zoomed in on our Red Planet neighbor, spying some lovely detail in its mountains, plains, icecaps and clouds. The photo opportunity came as Earth and Mars near opposition — meaning we are currently at the point of closest approach to Mars in our orbit — but the peculiarities of planetary orbits has made this opposition extra-special.

Although Mars and Earth’s orbits are approximately circular around the sun, they are slightly elongated, meaning that both planets drift closer to the sun at certain times. Should Mars be a little closer to the sun during opposition, the Mars-Earth distance will be even smaller.

Earth orbits the sun every 365 days; Mars orbits the sun once every 687 Earth days.

Opposition occurs once every 26 months or so, but on May 22, the two planets will come within 0.503 AU (or 46.78 million miles) of each other, making this the closest opposition for 10 years. The closest opposition in recorded history occurred in 2003 when Mars came within 34.65 million miles from Earth.

Of course, this celestial alignment produces a rare opportunity for Earth-bound astronomers. When Mars is at opposition, we can see the planet appear brighter in the night sky as it is located in an anti-sunward direction. And, as if peeking over the interplanetary fence, Hubble took the opportunity to see Mars’ full frontal, giving us a global view of a completely sun-lit hemisphere.

Captured in this observation are some famous features, including Hellas Basin, Schiaparelii and Hugens craters, plus the cratered Arabia Terra and the north polar icecap:

Features in the Martian atmosphere are also obvious, proving us with a snapshot of global cloud cover that can be used with previous Hubble observations to understand climate dynamics. Large scale changes on the planet’s surface can also be tracked.

Read more at Discovery News