Comments on: Sic Transit, Glorious

By: Neil Haggath

Neil Haggath — Wed, 13 Jun 2012 12:26:43 +0000

#15 Alph, #16 Rich W:
The orbits of Venus and Earth are inclined at 3.4 degrees to each other. If they were in the same plane, we would see a transit of Venus at every inferior conjunction, i.e. every 583.9 days! Because of this inclination, at most inferior conjunctions, Venus passes slightly above or below the Sun; a transit only occurs when a conjunction coincides with one of the nodes, the two points where the orbital planes intersect. In fact, it can be a little way off from the node to either side, due to the big apparent size of the Sun, which is why we don’t see it cross the centre of the Sun.
It’s the same as why we don’t get a solar eclipse every month – because the Moon’s orbit is also inclined to that of the Earth.
The time between successive inferior conjunctions of Venus, called the synodic period, is 583.9 days. 5 synodic periods is very nearly – but not quite – equal to 8 Earth years and 13 Venus years; so every 8 years ( 8 years minus 2.5 days, to be exact ), a conjunction occurs at very nearly the same place in the orbits. This explains why transits occur in pairs 8 years apart; the shift in position after 8 years is small enough that the conjunction again occurs close enough to the node for a transit to occur, but then after another 8 years, it’s just too far away from the node.
Hope that helps.

By: Andrew

Andrew — Fri, 08 Jun 2012 17:20:43 +0000

A great video – I missed the whole event in the UK due to cloud at 5am! – but like some people who have commented earlier I can see what appears to be the limb of the Sun “inside” Venus between first and second contact. Some kind of video artefact, perhaps?

By: John

John — Thu, 07 Jun 2012 15:18:18 +0000

Great music with the video–who did it?

By: mike burkhart

mike burkhart — Thu, 07 Jun 2012 14:19:57 +0000

That was grate!

By: Paul

Paul — Thu, 07 Jun 2012 05:20:35 +0000

I was able to bring my telescope to my High School and have it set up in time for the transit to start 5 min after school ended. The skies had been overcast all day but the clouds broke about 30 min before things started and we had great visibility right through til the sun set. About 50 students and staff had the curiosity to come check it out during the 45 minutes I stayed at school and then another dozen or so neighbors when I set up again at home. It was fun to share the event with others.

By: Don Gisselbeck

Don Gisselbeck — Thu, 07 Jun 2012 01:40:27 +0000

It was cloudy and rainy in Missoula, Montana, but a few of us from the Missoula City Band played Sousa’s Transit of Venus March during the transit. http://www.youtube.com/watch?v=41_-kgRXDBA

By: Paul

Paul — Thu, 07 Jun 2012 00:29:39 +0000

The ghost effects inside the circle of Venus could be video compression artifacts.

By: Clint L

Clint L — Wed, 06 Jun 2012 23:10:41 +0000

Is it a trick of the brain/eye or real? In watching the video several times, I perceive a change in the vision of the parts of the sun past which Venus transits. It is like looking through heat haze at a distant object. A bit weird considering the heat in the distant object, but that is the effect I’m getting, a slight disturbance in the vision.
It is like Venus has more than an atmosphere but something further out so it not only appears to leave a trail of disturbance but also pushes an envelope of disturbance.

Or it is just my brain making up stuff from too many views of the video?

Anyone else getting that?

By: Matt B.

Matt B. — Wed, 06 Jun 2012 22:29:12 +0000

The part at 2:00 where it changes filters gives me an idea: I’d like to see a video of the Sun that (as nearly as possible) continuously changes the wavelength of light that’s being viewed.

In reference to Ray Bradbury, we can also use the Babylon 5 episode title “Sic Transit Vir”.

By: Venus Transit footage from SOHO « Softology's Blog

Venus Transit footage from SOHO « Softology's Blog — Wed, 06 Jun 2012 22:23:41 +0000

[...] to The Bad Astronomer for the link. I knew that Phil would find the best example of the transit after it was all over and [...]