Transit of Venus from Mars
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A transit of Venus across the Sun as seen from Mars takes place when the planet Venus passes directly between the Sun and Mars, obscuring a small part of the Sun's disc for an observer on Mars. During a transit, Venus can be seen from Mars as a small black disc moving across the face of the Sun.
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[edit] Frequency of occurence
No one has ever seen a transit of Venus from Mars, but the next one will take place on August 20, 2030, and could be observed by spaces probes or hypothetical Mars colonists. Transits of Venus from Mars occur much more often than transits of Earth from Mars, and also much more often than transits of Venus from Earth.
The Venus-Mars synodic period is 333.92 days. It can be calculated using the formula 1/(1/P-1/Q), where P is the orbital period of Venus (224.701 days) and Q is the orbital period of Mars (686.98 days).
The inclination of Venus' orbit with respect to Mars' ecliptic is 1.94°, which is less than its value of 3.39° with respect to Earth's ecliptic.
[edit] 'Series'
From empirical observation of transit dates, it appears that transits occur within separate series; within each series, the transits are separated by 24042.45 days (just under 65 years and 10 months). This corresponds to 72 Venus-Mars synodic periods, or 35 Mars orbital periods, or 107 Venus orbital periods.
A series begins and ends with a near-miss just north or south of the Sun. When the distance between Venus and Mars at inferior conjunction is large enough (with Venus having an angular diameter of around 19"), a new series starts before the old one has ended. In this case transits occur only two synodic periods (about 668 days) apart, with one such transit catching the northern part of the Sun and the other catching the southern part of the Sun. However, when Venus and Mars are closer together at conjunction (with Venus having an angular diameter of around 23"), then one series ends before the other begins.
In the table below, series names beginning with "A" are near the ascending node with respect to the Martian ecliptic, and occur when Venus has an angular diameter of approximately 23–24". Series names beginning with "D" are near the descending node with respect to the Martian ecliptic, and occur when Venus has an angular diameter of approximately 18–19". It can be seen that Da2 starts before Da1 ends, and Db2 starts before Db1 ends, and Db3 starts before Db2 ends; however, Aa1 ends before Aa2 starts, and Ab1 ends before Ab2 starts.
Near misses are indicated with strikeout.
[edit] See also
| Transit visibility from planets superior to the transiting body | ||||||
|---|---|---|---|---|---|---|
| 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 | ||||
| Saturn | Saturn | |||||
| Uranus | ||||||
[edit] References
- Albert Marth, Note on the Transit of the Earth and Moon across the Sun’s Disk as seen from Mars on November 12, 1879, and on some kindred Phenomena, Monthly Notices of the Royal Astronomical Society, 39 (1879), 513–514. [66]
