Image credit: http://en.wikipedia.org/wiki/File:Venus_transit_2012_Minneapolis_TLR1.jpg
For the past few days, I've been hearing that there would be a transit of Venus on the Sun. As I woke up this morning, all news channels were telecasting this news and we thought we'll get into the Nehru Planetarium to get a better view and they would have made arrangements like telescopes and glasses to view the Sun.
We reached Nehru Planetarium at around 9:30 in the morning, there were quite a few astronomy enthusiasts crowded near the Telescopes set by the Planetarium. Few of them had bought the Solar Glasses to view the Sun. Few were watching through the Welder's Glass. There were few volunteers too, who were helping set-up the telescope positioning every now and then. Bangalore was a little cloudy this morning so, ofttimes the clouds would cover the Sun.
When I viewed through the telescope, I could see a black spot on the Sun. By then, the spot was moving towards the end of the Sun's arc. I saw through the Welder's glass as well. All I could see is the Sun directly. But I couldn't trace the Venus spot within. Later at 10:00 AM, once again I watched through the Welder's Glass, the person who handed me the glass said, you can see the spot one the left hand side at the 11 o'clock position near to the arc. I could then spot a little mark on the Sun. But it was clearly visible through the telescope.
We then, entered the Planetarium gallery. Apart from the Astronomy information, there was a Projector displaying the Venus Transit and the NASA live telecast of the transit. On another side, there were couple of Volunteers, exhibiting the transit models and explaining the transit process. It was really educative. The guy explained the process in a very simpler way.
It goes this way, as per my understanding: "The Earth and all other planets orbit around the Sun which is the universal truth. It takes 365 days (365.25 days to be precise) for the Earth to orbit round the Sun. Venus too orbits round the Sun. However, Earth orbits the Sun slower than Venus. Which means the Sun, Earth and Venus come in conjunction once in 1 years 6 months. So, why do we not see the Transit or Conjunction from Earth every 1.6 years? It's visible only when Venus, with an orbit inclined by 3.4° relative to the Earth's, usually appears to pass under or over the Sun. This specific conjunction taken place at a peculiar intervals of 8 years (Which was on 8th June 2004), 121 years (to be precise 121.5 years - the current transit), 8 years (Next transit is on December 2117) and 105 years (105.5 which will be on December 2125).
We had a question, when the orbit is divided by two: one segment of the orbit takes 105.5 years and the other segment takes 121.5 years to orbit round the Sun. Since the shape of the Sun is elliptical, the time-frame varies from one segment to the other.
So, the last transit and current transit was important for us, as none of us are sure to make it to 100+ years of life from now. ;)"
Thanks to the volunteer at the Nehru Planetarium for providing us with the above information.