The All-You-Need-To-Know-And-More Guide To The Venus Transit on June 5/6
By on June 2nd, 2012

It’s really an eclipse, but not quite. When Venus moves across the disc of the Sun on the 5th/6th of June, you’ll be witnessing history – and be able to realize how lucky you really are! In this article, I plan to provide you with everything you need to know in order to watch the transit and also appreciate the significance of this cosmic event!

A time-lapse photo of the 2004 transit

Basic Facts

Here’s the deal: Venus will be making its way around the Sun like normal, but this time, we will be behind it to observe. We will be seeing Venus move across the Solar Disc through nearly 7 hours. The last transit happened in 2004 and this one is occuring faithfully after 8 years. The next one will, however, occur after 105 more years – in 2117!

Venus Transit (Courtesy: GSFC/NASA)

So this is your last chance to see a Venus transit! Yes, there are many questions that you suddenly have in your mind right now, and I will try and answer all of them as we go along in this article.

Location Location!

The event will not be visible all over the world. There will be parts of the world, like Western part of Africa and Eastern part of South America, which will just miss the event completely. Sorry Brazil and Argentina. That said, the good news is that large parts of the world will definitely see the event.

Visible or not? Check for your location

Asia

Date: 6th June

The whole event
East Asia will be lucky to witness the whole nearly-7 hour event! By the time Venus enters the disc of the Sun, it will already be sunrise in these regions. Venus will exit the solar disc before sunset.
From sunrise till end
India and countries to the west of India, like Pakistan, Afghanistan and the entire Gulf region, will miss the start of the transit. Almost the entire Indian subcontinent will see the transit 3 hours after it starts. That’s no reason to fret, however; the transit will still be pretty long!

Europe

Date: 6th June

From event start till sunset
Most of Europe will be seeing the last part of the event. Venus will already have entered the solar disc by the time the sun rises and then it will exit before sunset. The unfortunate countries will be Spain and Portugal. While Spain will be getting a small last bit of the transit pie, Portugal will miss out on the event completely, as Venus will be just touching the solar disc at sunset.

North America

Date: 5th June

From Event start till Sunset
The event actually occurs when the date is 5th June, owing to its position on the other side of the International Date Line. So Venus will just touch the Sun’s disc at some point in the day. The transit will be visible till the Sun sets. Venus will still be within the Solar disc at sunset.
If you’re in Alaska for some reason, you might not be able to see Russia, but will definitely get to witness the whole transit.

South America

Date: 5th June
If you’re anywhere on this continent, you have really bad luck! Only the north-western parts of the continent will get to see any transit. That too, it won’t be for too long!

How to Watch

This is the most important question after ‘when is it happening?’. Looking directly at the Sun is sheer stupidity, so you’ll need some equipment.

The cheapest and least effort-requiring alternative

Solar goggles will be sold in your neighbouring areas somewhere. Get them. Make sure that these are proper by checking that you can look at the sun comfortably without your eyes hurting even a bit! Make-shift goggles made out of old X-Ray plates might not be a good idea, especially for the sun in the afternoon or late morning. Venus or no Venus, your eyes are the most important things to take care of. Never forget that!

Children in China looking through the goggles during the Solar Eclipse

Cheap alternative, but requires a bit more handiwork

One cheap way to look at the transit is to project it. You’ll need a few things and I think you’ll enjoy the thrill of making a simple tool to observe a cosmic event. You’ll need two magnifying lenses – one being the eye-piece and the other the objective. Make sure that the objective is a bigger lens than the eyepiece. Make a simple cardboard roll. Place another roll inside it, so that it fits snugly, but can still slide without too much of a problem. Place lenses properly within the rolls (before sticking them permanently, of course), so that you can get a decent image. Adjust the distance after that by sliding one cardboard roll against the other and ensure proper focus. Aim it at the sun and project it onto a white sheet of paper.

If properly focussed, you should be able to see Venus quite clearly! Strict warning: Do NOT look through the telescope while it is aimed at the sun. This is more dangerous that looking directly at the Sun, since the telescope actually collects sunlight and focuses them. You’ll run a serious risk of being blinded! Do NOT do it!

Not so cheap alternative

If you’re a member of the local amateur astronomy club, or if they are organising something in the locality, then, filters on a proper telescope is the best way to go! Make sure the guys use proper filters – red-orange filters are the way to go. The filters should be of good make, otherwise prolonged exposure might damage the filters and, in turn, the telescope CCD. With the filters installed, you can actually look directly at the Sun! The glory of Venus making its way should be evident! The upside of a fancy telescope is that you’ll also be able to see a few sunspots.

Home-made Baader filter cover for telescope. Try and get them. They don't come too cheap. (Photo courtesy: backyard-astro.com)

The filters aren’t too expensive, but they aren’t dirt cheap either! So if you’re the handyman and your friend has a telescope, collaborate to set up something that you can tell your grandchildren about.

Capturing on the Camera

Unfortunately the only way to get a good image of the transit on film (real or virtual) is to actually point the camera into the sun and click. With the Sun being so bright, this is a very bad idea; your camera CCD/film will not like it! The only way around that is filters. Make sure you have red-orange filters of appropriate shaped for your camera lens, before you even think of aiming at the Sun and clicking. Contact your local amateur astronomy club(s) or planetaria for the exact filters needed and available. Search for ND5 filters (Neutral Density-5 filters), if possible.

What to watch for

Venus entering and/or exiting the solar disc will be a treat. It will look like an oil drop falling into a liquid. Venus has a dense atmosphere, making the edges of the planet blur out against the bright disc of the Sun. Towards the end of the transit, a thin sliver of the sun’s disc will be visible between the edge of Venus and the edge of the solar disc. As Venus proceeds further, this sliver will also be “pinched off”. That’ll be a sight to behold.

The Venus Cycle!

Now, onto the real nitty gritty of the cycle of Venus. When can we see the transit and does it really have a period?

It turns out that it does – a massive period of 243 years! The transit of Venus will occur in a pair and then be separated by a relatively long time. The pair transits will differ by 8 years. The last transit occured in 2004 and this one is occuring this year – after 8 years, on the dot! But then this will be separated by a long 105.5 years, with the one after this year’s occuring in 2117 (December). The cycle is pretty complicated. The one after that will occur in 2125 – after the proper 8 year cycle (December again!). The one after that will occur after 121.5 years!

So the complicated cycle looks like this: 8-105.5-8-121.5 years between two successive transits. This entire 243 year cycle is then repeated. Look above for the diagrammatic representation.

Summary

So let’s look at the takeaway points:
1.Take a look at the GMT time and figure out the time for the transit in your area.

2.Make sure that you have proper equipment for observing the event. Do NOT see it with the naked eye. Projection onto a surface is an easy way. But it will require a little preparation. Youtube videos are your friends!

3.Look for solar goggles of good make. Remember, your eyes are of foremost importance, not Venus! The best solution – and the most expensive one – is buying filters for a telescope. This will give you a magnified and sharp image.

4.If you are geographically lucky enough to see the start or the end, do keep an eye out for the “pinch-effect”.

Have fun! Watch the Venus Transit safely.

Tags:
Author: Debjyoti Bardhan Google Profile for Debjyoti Bardhan
Is a science geek, currently pursuing some sort of a degree (called a PhD) in Physics at TIFR, Mumbai. An enthusiastic but useless amateur photographer, his most favourite activity is simply lazing around. He is interested in all things interesting and scientific.

Debjyoti Bardhan has written and can be contacted at debjyoti@techie-buzz.com.
  • cleitenag

    Brilliant guide.

    Can you elaborate a bit on why watching it through X-ray plates isn’t a good idea? it is rather popular.

 
Copyright 2006-2012 Techie Buzz. All Rights Reserved. Our content may not be reproduced on other websites. Content Delivery by MaxCDN