March: Conjunctions Continue

March 2012

Conjunctions Continue

By Calvin L. Chrisman

Jupiter Venus Conjunction 3.2012 National Geographic
March 2012 conjunction as seen from France. Source: National Geographic.

The continuing conjunction of Jupiter and Venus is drawing spectators throughout western North Carolina. At the beginning of the month, these lustrous planets are only ten degrees apart in the western sky; visible even before sunset and for several hours after. By Friday, the 9th, they were only five degrees and were three degrees apart from March 12th to the 14th as Venus rises above Jupiter while Jupiter moves lower in the west. As March progresses, Venus will continue to move up the sky, reaching forty degrees above the horizon by the end of the month. This will be its highest elongation east of the Sun for its eight year apparition cycle. If you are looking shortly after sunset early in the month, follow the line from Jupiter to Venus and down toward the horizon and see if you can spot faint Mercury following behind the Sun. By mid-month, Mercury will have become too faint to see without binoculars.

Venus, named after the Roman goddess of love and beauty, is the second brightest object in the night sky after the Moon. Its brightness derives from its closeness to Earth and the fact that it is shrouded by dense clouds of carbon dioxide, sulfur dioxide and sulfuric acid droplets! Venus’s orbit is closer to the Sun than Earth’s and so we always observe it somewhere in the vicinity of the Sun. Depending on its orbital cycle, it will be either following the Sun in the evening sky (as it is currently) or preceding the Sun in the morning sky. For this reason, it is often called the evening star or the morning star. Some ancient civilizations actually thought of Venus as two separate stars. The Greeks referred to the morning star as Phosphorus (meaning “Light Bringer”) and the evening star as Hesperus. The Romans called the morning star Lucifer (meaning “Light Bearer” – the name was not used for the devil until the third century) and the evening star was Vesper. Seen through a telescope, Venus has phases like we see on the Moon. Currently, it is about 58% illuminated.

After you have finished viewing the dramatic conjunction in the west and searching for Mercury, turn to the east and look for Mars. It is burning a brilliant red in the constellation Leo. It is below and to the left of Regulus, the heart of Leo the lion and the base of the prominent sickle of Leo. Regulus is one of the brightest stars in the sky, but will appear dim compared to Mars. Regulus is actually a system of four stars organized into two pairs. If you keep watching this pair as the month progresses, Mars will move closer to Regulus and Saturn will rise in the east by 10:00 p.m. near the end of the month.

Spring will begin at 1:14 EDT on the morning of March 20th (what happened to our winter?). This is the point when the Sun crosses the equator on its path to the summer solstice in June.

Clear Skies!

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