Exogeology ROCKS!

Image credit: NASA

Tomorrow, you’ll have a once-in-a-lifetime opportunity to actually see a planet cross over a star. Venus transits our sun for the last time in over a century at 22:09 UTC, June 5th, so find a way to watch.

Why is this so special?

If you have any astronomer friends, they’ve probably been blabbering on for months about orbital periods this, first contact that. Why won’t we shut up? Because this is literally once in a lifetime, and it’s kinda cool.

Venus, the next planet inward, will cross directly over the visible disc of the sun. It will appear as a tiny black dot, about one arcminute, covering a minuscule fraction of the disk. This isn’t a lot, but it’s enough to see with the naked eye—not the recommended way to view it, of course.

Venus’ orbit is slightly skewed compared to Earth’s, so Earth, Venus, and the sun only line up this way every 121.5 or 105.5 years. After this much time, Venus gets in the way of the sun twice, each time eight years apart. The last transit was eight years ago. The next, after tomorrow’s, will be in the year 2117.

Transits of Venus were historically used to calculate solar parallax. This eventually led to the astronomical unit, the distance from here to the sun, giving us a way to measure the solar system. Today, scientists’ observations of the transit will help in studying exoplanets.

Do you have a way to live 105.5+ more years or own a time machine? If so, I take back what I said about this being once-in-a-lifetime. Maybe it’s not so special. Even still, what’s the harm in watching?

How can I watch?

If you have vision and plan to keep it, then just going outside and staring at the sun isn’t the method for you. Consider these options instead:

• Try making a pinhole projector.
• Use eclipse glasses. These can be bought online or possibly at your local science museum gift shop. Don’t count on the museum shop though—they might have sold out with all the solar viewing going on lately.
• If you have a telescope, use a filter on the front end (not the eyepiece) to protect your eyes and your telescope. Having a bit of magnification will help turn Venus from a tiny speck to a slightly less tiny speck.
• Do you or a friend weld? No? Huh. Well, for those who do, wear #14 welder’s goggles to safely view the transit.
• Do you have access to a device such as a computer, phone, or tablet which can connect to the internet? If not, can you please explain to me why somebody printed my website? If you do have access, check out NASA’s webcast from Mauna Kea, Hawaii.

Have fun, view safely, and keep me in the loop about that time machine!