It's a celestial spectacle that is truly once in a lifetime—unless you saw it in 2004, or plan on living until the year 2117.
Venus will be seen inching its way across the sun this week, in what astronomers refer to as a "transit of Venus," lasting around six and a half hours on Tuesday afternoon in the Western Hemisphere and Wednesday morning in the Eastern Hemisphere. Observatories, museums, and schools are all hosting viewing parties, and if you're not able to see it live yourself, NASA will post a live webcast.
Hundreds of astronomers—some from warring countries—watched Venus crossing the sun in the 1700s.They used unprecedented global teamwork in the scientific community to determine from the transit our own distance from the sun—a technique still used to find alien worlds beyond our solar system.
Whether this transit will deliver new revelations this century remains to be seen, but remember: Use a pin-hole projector or some other safe method of viewing. Staring at the sun can have negative effects on you.
Video by Jim Festante.