The phases of Venus

The Phases of Venus

Venus orbits the Sun inside our orbit. Consequently, Venus shows phases, i.e., changes in its apparent shape, much like the moon. This is a composite of several images of Venus taken at different intervals to show how the phase of Venus changes as it moves around its orbit relative to our vantage point. When Venus shows a near full phase, it is on the far side of the Sun and appears relatively small because of its greater distance from us. As it reaches its maximum elongation from the Sun, it displays a half phase. When it swings around and passes between us and the Sun, it displays a crescent phase and swells in size until it disappears in the glare of the Sun at inferior conjunction.

At rare intervals, we get to see Venus cross in front of the Sun at inferior conjunction. Transits of Venus only occur twice every 121 years, and the two transits are themselves 8 years apart. Transits of Venus always occur in either December or June. A transit of Venus occurred on June 8, 2004, and will be followed by another transit on June 6, 2012. If you miss those transits, you will have to wait until 2117 for another one. Mercury will also sometimes transit across the Sun, but Mercury transits are not as rare as a Venus transit.

This is a mosaic of CCD images and photographs taken at various times with a Takahashi FCT-150 refractor and Takahashi Mewlon 210 telescope.

Images by Sid Leach
Scottsdale, Arizona

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