Long Days (and Nights), But Shorter Years

If you were born on Venus, you'd celebrate your first birthday before you've experienced one full day

[On June 5, 2012, Venus passed directly between the Earth and the Sun, a rare astronomical phenomenon known as the "Transit of Venus" that will occur again in 105 years. This month, 13.7 Billion Years considers "Earth's twin," from the scientific study of the planet to its mythological underpinnings, with the series Second Rock from the Sun.]

Earth and its so-called twin may be similar in many ways. Orbit and rotation are not two of them.

While all of the planets have elliptical orbits, Venus's orbit is nearly circular, with an eccentricity of less than 0.01.

Also, all the planets except Venus and Uranus rotate counter-clockwise (when viewed from their north poles).

Venus also has by far the slowest rotation of any planet, taking 243 Earth days to rotate once. Since it completes its orbit around the Sun every 224.65 Earth days, Venus has the unusual situation of having longer solar days (sunrise to sunrise) than years, a condition it shares only with Mercury.

If you were on the surface of Venus, you would see the Sun rising in the west and setting in the east. And then you'd experience a Venusian night that lasted almost 117 Earth days. For night owls, perhaps that's a good thing.

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image: A portion of western Eistla Regio is displayed in this three-dimensional perspective view of the surface of Venus. The viewpoint is located 1,100 kilometers (682 miles) northeast of Gula Mons at an elevation of 7.5 kilometers (4.6 miles). Lava flows extend for hundreds of kilometers across the fractured plains shown in the foreground to the base of Gula Mons. The viewpoint is to the southwest with Gula Mons appearing at the left just below the horizon. Gula Mons, a 3 kilometers (1.8 miles) high volcano, is located at approximately 22 degrees north latitude, 359 degrees east longitude. Sif Mons, a volcano with a diameter of 300 kilometers (180 miles) and a height of 2 kilometers (1.2 miles), appears to the right of Gula Mons. The distance between Sif Mons and Gula Mons is approximately 730 kilometers (453 miles). Magellan synthetic aperture radar data is combined with radar altimetry to develop a three-dimensional map of the surface. Ray tracing (rays as if from a light source are cast in a computer to intersect the surface) simulate a perspective view. Simulated color and a digital elevation map developed by Randy Kirk of the U.S. Geological Survey, are used to enhance small scale structure. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft. The image was produced at the JPL Multimission Image Processing Laboratory by Eric De Jong, Jeff Hall and Myche McAuley, and is a single frame from a video released at a March 5, 1991, JPL news conference. (credit: NASA/JPL, Wikimedia Commons)