Look skyward, space-lovers: Tuesday, June 5 is the last chance in your lifetime to see the transit of Venus across the face of the sun.
Venus won't visibly pass between the Earth and the sun again until 2117, so get your special sun-viewing glasses now. In North America, the transit will start in the hours before sunset on June 5. Viewers in Asia, Australia, Africa and Europe can catch the transit at sunrise on June 6. The transit will begin at about 6:03 p.m. EDT, 5:04 p.m. CDT, 4:05 p.m. MDT and 3:06 p.m. PDT.
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From Earth, Venus will appear to cover just 1/32 of the face of the sun, so you'll need "very good conditions and very good eyes" to view the event without magnification, according to Nick Schneider, an astronomer at the University of Colorado, Boulder. But you still need protective eyewear, because without it, the intensity of the sun's light can cause serious retina damage.
If you have your own telescope with a sun filter, you can set it up to project an image of the sun on a sheet of paper or the ground, Schneider said. Never look directly at the sun without a specialty filter.
The most satisfying way to view the transit will likely be to go to a local museum or planetarium that has a special sun-viewing telescope set up. For those who can't arrange an in-person viewing, the transit will be streamed online from multiple observatories and telescopes across the globe.
Why so rare? Transits of Venus occur in pairs eight years apart separated by either 105.5 years or 121.5 years. The last Venus transit occurred in 2004, and the next pair won't happen until 2117 and 2125. The reason transits are so rare is that Venus' orbit is off-kilter from Earth's orbit by about 3.4 degrees. That means that when Venus does pass between the Earth and the sun, it's often too low or high to cross in front of the sun's face.
"We tend to think of our solar system layout as perfectly organized with all the planets going around in the same direction all lined up, the truth is that small amounts of misalignment matter a lot."
There have been only seven transits of Venus since the invention of the telescope in 1610, according to NASA. They occurred in 1631, 1639, 1761, 1769, 1874, 1882 and 2004. Views of Venus