Syzygy (astronomy)
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In astronomy, a syzygy is a roughly straight-line configuration of three or more celestial bodies in a gravitational system.
A syzygy occurs during eclipses (numbers 1, 2, 3, 4).
Jupiter (top), Venus (lower left), and Mercury (lower right) above La Silla Observatory, Chile (May 26, 2013)
Apparent planetary alignment involving Mercury, Venus, Mars, and Jupiter; the Moon is also shown, as the brightest object.
Full Moon 2010
Appulse
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Appulse is the least apparent distance between one celestial object and another, as seen from a third body during a given period. Appulse is seen in the apparent motion typical of two planets together
The Moon and Venus in the evening sky on three consecutive days. The centre image shows an appulse between the two objects.