Astronomy & Astrology - Venus (planet)

Venus (planet)

Venus (planet), one of the planets in the solar system, the second in distance from the sun. Except for the sun and the moon, Venus is the brightest object in the sky. The planet is called the morning star when it appears in the east at sunrise, and the evening star when it is in the west at sunset. In ancient times the evening star was called Hesperus and the morning star Phosphorus or Lucifer. Because of the distances of the orbits of Venus and earth from the sun, Venus is never visible more than three hours before sunrise or three hours after sunset.

Venus is the brightest object in our sky, after the sun and moon. Swirling clouds of sulfur and sulfuric acid obscure Venus's surface and inhibited study of the planet from Earth until technology permitted space vehicles, outfitted with probes, to visit it. These probes determined that Venus is the hottest of the planets, with a surface temperature of about 460° C (about 860° F). Scientists believe that a greenhouse effect causes the extreme temperature, hypothesizing that the planet's thick clouds and dense atmosphere trap energy from the sun.

NASA/Science Source/Photo Researchers, Inc.

When viewed through a telescope, the planet exhibits phases like the moon. Full Venus appears the smallest because it is on the far side of the sun from earth. Maximum brilliance (a stellar magnitude of -4.4, or 15 times the brightest star) is seen in the crescent phase. The phases and positions of Venus in the sky repeat with the synodic period of 1.6 years. Transits across the face of the sun are rare, occurring in pairs at intervals of a little more than a century. The next two will be in 2004 and 2012.

Contributed By: Donald M. Hunten, Ph.D. Regents Professor of Planetary Sciences, University of Arizona. Author of Introduction to Electronics. Coauthor of Theory of Planetary Atmospheres.

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