Transit of Mercury from Saturn

A transit of Mercury across the Sun as seen from Saturn takes place when the planet Mercury passes directly between the Sun and Saturn, obscuring a small part of the Sun's disc for an observer on Saturn. During a transit, Mercury can be seen from Saturn as a small black disc moving across the face of the Sun.

Naturally, no one has ever seen a transit of Mercury from Saturn, nor is this likely to happen in the foreseeable future. Nevertheless, the next one will take place on December 30 2011.

A transit could be observed from the surface of one of Saturn's moons rather than from Saturn itself. The times and circumstances of the transits would naturally be slightly different.

The Mercury-Saturn synodic period is 88.694 days. It can be calculated using the formula 1/(1/P-1/Q), where P is the sidereal orbital period of Mercury (87.968 days) and Q is the orbital period of Saturn (10746.940 days).

The inclination of Mercury's orbit with respect to Saturn's ecliptic is 6.38°, which is less than its value of 7.00° with respect to Earth's ecliptic.

Transits of Mercury from Saturn are empirically observed to occur in clusters, with two such clusters every 30 years or so.

The transit that occurred on March 21 1894 was particularly interesting, because it happened on the same day as transits of Venus from Saturn and of Mercury from Venus. But no two of the transits were simultaneous. Also interesting is the event of December 9 2056, when Mercury barely misses transiting the Sun, and Venus begins a transit about six hours later.

Note: the image linked to in the following table does NOT take into account the finite speed of light. The distance of Mercury from Saturn at inferior conjunction is approximately 9.3 AU or about 80 light-minutes. It will take about 8 hours for Mercury to transit across the Sun, thus the image corresponds fairly closely to what would actually be seen by an observer on Saturn.

ee also

* Astronomical transit

References

* Albert Marth, "Note on the Transit of Mercury over the Sun’s Disc, which takes place for Venus on 1894 March 21, and on the Transits of Venus and Mercury, which occur for Saturn’s System on the same day", Monthly Notices of the Royal Astronomical Society, 54 (1894), 172–174. [http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?1894MNRAS..54..172M]

External links

* [http://space.jpl.nasa.gov/ JPL Solar System Simulator]