Elongation
From Wikipedia, the free encyclopedia
Elongation is an astronomical term that refers to the angle between the Sun and a planet, as viewed from Earth.
When an inferior planet is visible after sunset, it is near its greatest eastern elongation. When an inferior planet is visible before sunrise, it is near its greatest western elongation. The value of the greatest elongation (west or east), for Mercury, is between 18° and 28°; and for Venus between 45° and 47°. This value varies because the orbits of the planets are elliptical, rather than perfect circles.
Refer to astronomical tables and websites such as www.heavens-above.com to see when the planets reaches their next elongations.
In 2007 Venus has a greatest eastern elongation on June 9, and a western one on October 28.
In 2007 Mercury has greatest eastern elongations on February 7, June 2, and September 29. Western ones happen on March 22, July 20, and November 8.
[edit] See also
- Aspects of Mercury for greatest elongations of Mercury
- Aspects of Venus for greatest elongations of Venus
- Astronomical conjunction
