Earth passage from Mars
A passage of the earth in front of the sun as seen from Mars occurs when the planet earth passes directly between the sun and Mars and covers a small part of the sun's disk for an observer on Mars.
During such a pass , the Earth of Mars can be seen through a solar filter as a small black disk moving across the Sun. The case is particularly interesting because the earth and moon can often be seen together in transit; however, sometimes one finishes the run before the other begins. A passage through the earth has never been observed by Mars probes ; the last such event took place on May 11, 1984. However, the next transit, which will take place on November 10, 2084, could be observed by future Mars colonists .
Observers on Mars could also observe Mercury and Venus transits as well as solar eclipses caused by the Martian moons Phobos and Deimos . Earth passages observed from Mars follow a 284-year cycle and occur at intervals of 100.5, 79, 25.5, 79 years in either May or November. This cycle corresponds almost exactly to 151 orbits of Mars or 284 orbits of the earth and to 133 synodic periods and is analogous to the cycle of the earthly passages of Venus, which follow a cycle of 243 years (121.5, 8, 105.5, 8).
During an earth passage from Mars, this is exactly in opposition to the sun for an earthly observer . The red planet then appears to be evenly illuminated - with a phase angle of 180 ° (“Vollmars”). With almost such an opposition in 1879 , Charles Augustus Young succeeded in determining the flattening of Mars, since the measurement is not falsified by Mars phases. It got a value of 1/219, or 0.46 percent, while the modern value is 1/193.
Science fiction
The writer Arthur C. Clarke , in his short story Transit der Erde , published in 1971, told the story of a team of astronauts who fled to Mars to observe the transit of the Earth on May 11, 1984.
| Passages in our solar system | ||||||
|---|---|---|---|---|---|---|
| Venus | earth | Mars | Jupiter | Saturn | Uranus | Neptune |
| Mercury | Mercury | Mercury | Mercury | Mercury | Mercury | Mercury |
| Venus | Venus | Venus | Venus | Venus | Venus | |
| earth | earth | earth | earth | earth | ||
| Mars | Mars | Mars | Mars | |||
| Jupiter | Jupiter | Jupiter | ||||
| moon | Deimos | Saturn | Saturn | |||
| Phobos | Uranus | |||||