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5.4 The VenusChart Function

VenusChart produces a wall chart that can be used to determine when Venus is visible in the morning or evening sky.

Charting the future positions of Venus.

Venus is in a near perfect orbital resonance with the Earth, with the result that the VenusChart graphic approximately repeats after eight years. Elongations to the right in the graphic are such that Venus rises before the Sun, and hence is visible in the morning hours just before dawn. Similarly, elongations to the left are such that Venus sets after the Sun, and hence is visible in the evening hours just after dusk. The phase and magnitude of Venus is indicated by icons scattered around the rim of the graphic.

This is the Venus finder chart beginning in year 1994 and ending in 2002.


To read the chart, locate the month (labeled with the letters J, F, M, A, M, J, J, A, S, O, N, D) and year desired, then move radially out to the outer ring to see the phase. If Venus is to the left of the graphic, it is visible in the evening sky just after dusk, and if it is to the right, it is visible in the morning sky just before dawn.

For instance, during April 1996, Venus is at its maximum elongation from the Sun and is visible in the evening sky.