Moon Venus Conjunction Makes Great Spectacle
Photos of the Venus-Moon Astronomy Event February 28th 2009
Mar 1, 2009
February 28th 2009 was an ideal time to view the planet Venus in conjunction with the Earth's only satellite, The Moon. Venus is the second planet from the sun, Earth's nearest neighbour in the solar system. It orbits the sun in a circular path at around 68 million miles radius from the sun, compared with 93 million miles' orbit radius of the Earth.
Why Does Venus Have Phases?
This means that at its farthest point from the Earth, Venus may be approximately 160 million miles away from the Earth - and consequently quite dim. However, as at the date of this article (end of February 2009), Venus is orbiting towards the Earth and consequently it appears to be particularly bright as it reflects the Sun's light, even though only part of the planet Venus is visible from Earth.
Venus appears as a complete disc when it is far away from Earth, but as it travels in its orbit towards or away from the Earth, it is visible in phases, rather like the phases of the Moon.
Venus - Morning Star or Evening Star?
In antiquity astronomers believed that there were two separate planets that appeared, one in the evening and one in the morning. Eventually the astronomers discovered that these were one and the same planet, Venus. The reason for this confusion is that when Venus is moving toward the Earth, the planet can be seen in the early evening, and when moving away from the Earth, Venus is visible in the early morning.
Earth's Twin Planet?
Sometimes Venus is referred to as Earth's twin, since it is the closest in size, being approximately 400 miles smaller in diameter to the Earth. However, there the similarities end. Venus is a retrograde planet - that means its spin is opposite to its direction of orbit, which takes 243 Earth days to complete.
Venus is a very hot greenhouse planet; its atmosphere being made up largely of carbon dioxide covered in dense obscuring clouds of sulfuric acid which prevent heat from being released into space. There is no surface water on Venus as the temperature is too high and liquids would boil instantly. The cloud temperature has been measured at 55 degrees C, whilst the planetary surface temperature is believed to be 870 degrees C - making it the hottest planet in the Solar System.
References
W. Head, III, Ph.D., Professor of Geological Sciences, Brown University, NASA.com
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