The Evening Star
You may have noticed a very bright ‘Star’ close to the western horizon just after sunset. It isn’t a star it is the planet Venus.
Because Venus is closer in to the Sun than we are it is known as an inferior planet along with Mercury and it never appears very far from the Sun either after sunset or before sunrise giving rise to its romantic title of the Evening Star or Morning Star.
Venus is the 2nd planet out from the Sun and is the closest planet to the Earth both in distance and in size, it is just slightly smaller than Earth. After the Moon Venus is the brightest ‘natural’ object in the night sky, although the International Space Station can sometimes outshine Venus. It is named after the Roman Goddess of love and beauty and it’s easy to see why with its dazzling brightness, but the truth is far from beautiful.
Venus goes around the Sun once every 224 days compared to our 365 days but a day on Venus lasts for 243 days so a day on Venus lasts longer than a year! Also while all the other planets in the solar system spin on their axis from west to east Venus spins the opposite direction from east to west. It is hard to imagine what a ‘day’ might look like on Venus with the Sun rising
very, very slowly in the west, staying in the sky for more than a year until slowly sinking in the east. That is if you could even see the Sun.
Venus is completely covered in a dense blanket of clouds so thick that you wouldn’t be able to see more than a few feet in front of you. These clouds are almost 96% carbon dioxide and sulphur dioxide, creating a runaway greenhouse effect that is causing the temperature to reach over 460ºC at the surface. It is even hotter than the planet Mercury even though Venus is nearly twice as far from the Sun as Mercury. The pressure at the planet's surface is about 92 times that at Earth's surface — a pressure equivalent to that at a depth of nearly 1 km under Earth's oceans.
There are winds of over 300mph and because of the thick atmosphere and pressure it would be like walking through a river of treacle. Volcanoes spew molten sulphur onto the surface and it ‘rains’ sulphuric acid. Venus has been described as the closest thing to Hell that you can imagine.
Both the Americans and Russians have sent several probes to Venus over the years but because of the horrendously inhospitable conditions at the surface none have survived more than a few hours before being either melted or crushed. Almost everything we now know about Venus has been collected from orbital probes that have used radar to map the surface. I think that the chances of astronauts ever landing on Venus even in the distant future is very unlikely indeed.
If you observe Venus through a telescope over the course of its orbit around the Sun it displays phases similar to those of the Moon. When it is at the far side of the Sun from us it appears as almost fully lit face. Then as it begins its journey it moves further and further away from the glare of the Sun as it gets closer to us. When Venus reaches its maximum to the side of the Sun then only the side facing the Sun is lit and we see a half phase. Then as it begins to move in closer to the Sun the phase gradually gets less and less until it is between the Sun and us and lost in the Sun’s glare.
Keep your eye on Venus over the next few months as it moves further away from the Sun until the beginning of April 2012 when it will be at its maximum from the Sun and dazzlingly bright in the night sky. Then for the next few months it will gradually move between the Sun and Earth until it reappears at the end of the year as the Morning Star, rising before the Sun in the east.
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