Transit of Earth...From Mars... Dec 27, 2005 2:30:03 GMT -6
Post by Chicago Astronomer Joe on Dec 27, 2005 2:30:03 GMT -6
Earth slides across the Sun's face from Mars - 2084 A.D.
No one has ever seen a transit of Earth from Mars, but the next one will take place on November 10 2084, and could be observed by hypothetical future Mars colonists. The last such transit took place on May 11 1984.
A 1971 science fiction short story by Arthur C. Clarke entitled Transit of Earth was about a doomed astronaut on Mars observing the 1984 transit; setting the story in 1984 turned out to be too optimistic. The short story was first published in the January 1971 issue of Playboy magazine.
Of course, observers on Mars can also see transits of Mercury and transits of Venus, as well as transits of Phobos and transits of Deimos.
Transits of Earth from Mars follow a 284-year cycle, occurring at intervals of 100.5, 79, 25.5, 79 years in either May or November. This cycle corresponds fairly closely to 151 Mars orbits, 284 Earth orbits, and 133 synodic periods, and is analogous to the cycle of transits of Venus from Earth, which follow a cycle of 243 years (121.5, 8, 105.5, 8).
A transit of Earth from Mars corresponds to Mars being perfectly uniformly illuminated at opposition from Earth, its phase being 180.0° without any defect of illumination. This permitted Charles Augustus Young to attempt a careful measurement of the oblateness (polar compression) of Mars during the 1879 event. He obtained the value 1/219, or 0.0046. This is close to the modern value of 1/154 (many sources will cite somewhat different values, such as 1/193, because even a difference of only a couple of km in the values of Mars' polar and equatorial radii gives a considerably different result).
More here: www.answers.com/topic/transit-of-earth-from-mars
I am reading Arthur C. Clarke's "The Snows of Olympus", an illustrated story of Man's colonization of Mars, in where he discusses the transit of Earth as seen from the surface of Mars. I thought I would post this actual future event here at the Chicago Astronomer.
It would be quite cool to witness...