The transit of Venus is cool.

I think we can all agree on that. On Tuesday, the planet Venus will pass between us and the Sun—a little black dot sliding across the face of a giant, yellow ball. Barring the Singularity, this will be your last opportunity to see a transit of Venus. The next one won't happen until December of 2117.

But, beyond looking nifty and reminding you of your own mortality, what, exactly, is the transit of Venus good for? Is this a cultural event, a scientific event, or a little of both?

Historically, the transit of Venus provided the data that allowed us to gauge the size of the solar system for the first time. This time around, according to Space.com, researchers will be watching the transit with an eye to the universe outside our solar system. That's because what we learn from the transit of Venus could help us identify planets (including Earth-ish planets) elsewhere in the galaxy.

Astronomers already key in on transits to search for alien worlds, often finding them by detecting the telltale dips in brightness exoplanets cause when they pass in front of their parent stars. NASA's Kepler space telescope has been very successful using this technique, flagging more than 2,300 candidate alien planets to date.

“During the transit, Venus Express will make important observations of Venus’ atmosphere that will be compared with ground-based telescopes to help exoplanet hunters test their techniques," said Håkan Svedhem, ESA’s Venus Express project scientist.

Read the rest of the Space.com story

Find lots of educational materials, how-tos, and useful transit of Venus information at TransitofVenus.org

Check out Discovery News' guide to safely photographing the transit of Venus