Posts Tagged ‘Phobos’

Eclipse from another world

29 June, 2009

Another planet to be exact.

When our Moon, Earth’s only satellite, blocks our view of the Sun, it gives us a solar eclipse. But what about the moon or moons on the other planets in out solar system?

Mars (the fourth planet from the sun, not the candy bar) has two natural moons, Phobos and Deimos.

To recap, a transit happens when an object that appears visually smaller passes in front of an object that appears visually larger.

Image: NASA

And this is what happens when Phobos passes between the Sun and Mars.

The transit only lasts 30 seconds or so due to the very rapid orbital period of 7.6 hours. Which means if you were standing on the surface of Mars, you would see a shadow glide across the disc of the Sun quite rapidly.

Because Phobos’ orbit is close to Mars and in line with its equator, transits of Phobos across the Sun occur somewhere on the Red Planet on most days of the Martian year.

Thanks to the Mars Rover Opportunity, we get to witness a “solar eclipse” from Mars — Phobos transiting the Sun.

As for Mar’s other moon, Deimos, it also transits the Sun when it passes between the Sun and Mars. Deimos has a relatively rapid orbital period of 30.3 hours, and a transit lasts a maximum of about 2 minutes.

Image: NASAAlso taken by the Mars Rover (isn’t technology simply wonderful), this is what a transit of the moon Deimos across the Sun would look like if you were on Mars.