transit of Venus

This article is about the astronomical phenomenon. For other meanings, see Transit of Venus (disambiguation). A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and Earth, obscuring a small portion of the Sun's disk. During a transit, Venus can be seen from Earth as a small black disk moving across the face of the Sun. The duration of such transits is usually measured in hours (the transit of 2004 lasted six hours). A transit is similar to a solar eclipse by the Moon, but, although the diameter of Venus is almost 4 times that of the Moon, Venus appears much smaller because it is much farther away from Earth. Before the space age, observations of transits of Venus helped scientists using the parallax method to calculate the distance between the Sun and the Earth.
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