Hi everyone! I’m writing this post to alert you to a very rare transit that you MUST see this year–if you don’t, you will never get the chance again. No seriously, you will never get to see it again. I’m of course talking about the transit of Venus across our sun, which will occur on June 6th (June 5th in some places due to the international date line), 2012. This rare event is when we, from Earth, will see Venus crossing in front of the Sun. This event will not occur again until December 11th, 2117. I don’t know about you, but I do not plan on living that long.
So what is a transit? In astronomy, transit actually has multiple meanings, but the one I am referring to, broadly speaking, is when one celestial object passes in front of a much larger one. We say that the smaller celestial object is the one that is transiting the larger one. When this happens, the smaller object blocks only a small fraction of the larger object—if the transiting object blocks most or all of the second one, we no longer call it a transit, we call it an occultation.
Keep in mind that you should not just look at the Sun during this event—I’m sure you all remember all of your elementary school teachers and parents telling you that if you look directly at the Sun, you’ll go blind. That’s still true, unless you use what’s called a filter. By looking at the Sun using the proper filter, you can block out a significant portion of the light, making it much safer to observe the Sun. The best way you can enjoy this rare event is to trek out to your local observatory or amateur astronomer gathering, where there is likely to be a telescope (or multiple telescopes) equipped with the proper filter. If you do not have access to a local gathering of Astronomy nerds, you can view the Sun safely at home with your own telescope!
Transits and occultations play a role in a lot of awesome Astronomy research, and in cool observable phenomena! For instance, one of the most useful and popular ways of detecting exoplanets is through transits! One of the most popular scientific missions currently being carried out is the Kepler mission: Kepler observes a large number of stars continuously, and is hoping to see an exoplanet transit in front of its host star! Similar to the Venus transit, planets in other solar systems can transit their own stars, which blocks out a small portion of the light coming from the star—Kepler can see this by observing a regular drop in the total light it sees from a star. Kepler is so precise, it can see extremely small drops, allowing it to find planets as small as Earth!
Of the phenomena I mentioned in the last paragraph, the most famous and breathtaking are those of solar and lunar eclipses! For a solar eclipse, the Moon is in the same line of sight as the Sun. However, since from Earth, the Moon appears to be the same size as the Sun, it can completely block out the Sun, causing a solar eclipse (although you still see the corona of the Sun, which is the extremely hot outer layer of the Sun’s atmosphere). For a lunar eclipse, it’s a little different—the Earth passes in front of the Moon-Sun line of sight, and the Moon ends up in the Earth’s shadow. Think of the last time you played with a flashlight—you project the light onto the wall, and then place your hand in front of the flashlight—this creates a shadow on the wall, which often looks like a really screwed up animal. This is because your hand is blocking out some of the flashlight’s light, and so you only see the remaining light on the wall. For a lunar eclipse, the Sun is the flashlight, the Earth is the hand, and the Moon is the lit up piece of the wall, except in a total lunar eclipse, the Earth completely blocks the Sun (the hand fully covering the flashlight). When this happens, you get a lunar eclipse.
I hope I’ve now convinced you that transits are really cool, and that you must do your best to observe this rare, awesome Venus transit on June 6th (or 5th)! Check where you need to be to see it, and what your best viewing options are! You won’t regret it.