04 May 2012

VENUS 2012! It's phases, transit, whereabouts PART 4

2 different phases of Venus
credit: KTY Toutatis Astronomy Club
(Click on picture to enlarge)
Venus, the second closest Planet to our Sun. The closest Planet to Earth, our twin sister and Morning Star as well as Evening Star. More Astrophotos of Phases of Venus HERE

Over the last months, At the Astronomy Club we have observe Venus to catch it's phases before the big day of the Transit on June 5-6.2012. The picture on the left shows 2 phases of Venus. We have the smaller "half-dot" that is Venus at 65% of full and the bigger crescent is Venus at 26% of full. These two observations of Venus are taken 2 months apart. The "half-dot" is taken on the 26 of February 2012 and the bigger crescent is taken on May 1 2012. You can clearly see the difference in the phases.
It was very nice to observe the changes in the phases of venus on it's own. You really get the feeling that it is true, and not only in the books.
The Phases of Venus result from the planet's orbit around the Sun inside the Earth's orbit giving the telescopic observer a sequence of progressive lighting similar in appearance to the moon's phases.
It presents a full image when it is on the opposite side of the Sun. It shows a quarter phase when it is at its maximum elongation from the Sun.
Venus presents a thin crescent in telescopic views as it comes around to the near side between the Earth and the Sun and presents its new phase when it is between the Earth and the Sun. Since the planet has an atmosphere it can be seen at new in a telescope by the halo of light refracted around the planet.

Crescent of Venus / phase 0.227
credit: KTY Toutatis Astronomy Club
(Click image to enlarge)
The full cycle from new to full to new again takes 584 days (the time it takes Venus to overtake the Earth in its orbit). The planet also changes in apparent size from 9.9 arc seconds at full (superior conjunction) up to a maximum of 68 arc seconds at new (inferior conjunction). Venus reaches its greatest brilliancy (magnitude –4.5) when it is an intermediate crescent shape at the point in its orbit when it is 68 million kilometers away from the Earth (a combination of its closeness and the fact that it is 28% illuminated).

Until the day of the Transit, that is in 31/32 days. We have the chance to picture Venus in it's thin crescent phase and see it grow in size.

Click HERE to read the 6th post of our journey through astronomy in Enontekiö, Lappland. 

Wikipedia: Phases of venus
More Astrophotos of Phases of Venus HERE 

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