It will be your last change to catch a glimpse of one of the rarest cosmic spectacles -- the slow movement of the planet Venus across the face of the sun.

The transit of Venus, which occurs when the planet's orbit brings it between Earth and the sun, takes place roughly twice a century.

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This year's transit is the second of an eight-year pair. The event is analogous to an annular solar eclipse. The transit begins the instant the planet's disk is externally tangent to the sun. Shortly after, the planet can be seen as a small notch traveling across the surface of the sun.

The entire event will be widely visible from the western Pacific, eastern Asia and eastern Australia, NASA said, using only a telescope. During the pass Venus appears as a small, dark round spot moving across the face of the sun, but don't look directly, scientists warn.

Venus covers too little of the solar disk to block the blinding glare, NASA stated. Instead, use some type of projection technique or a solar filter. A #14 welder's glass is a good choice.

The marathon event, which will last nearly seven hours, last occurred on June 8, 2004 - and won't happen again until 2117.

The show began around 6 p.m. EDT and end at roughly 12:50 a.m. EDT for sky-watchers in the United States. Even astronauts aboard the International Space Station are joining in.

I've been planning this for a while, space station flight engineer Don Pettit said in a NASA interview. I knew the transit of Venus would occur during my rotation, so I brought a solar filter with me.

There are plenty of opportunities to watch the event online. NASA's EDGE program is featuring which has a live feed from the top of Mauna Kea in Hawaii, starting at 5:45 p.m. PDT.

The NASA page also links to other live feeds around the world.

Local viewing times: 12:10 p.m. Honolulu, 3:06 p.m. Los Angeles, 5:06 p.m. Mexico City, 6:04 p.m. New York - all on Tuesday - and 5:37 a.m. London, 6:10 a.m. Beijing, 6:12 a.m. Hong Kong, 6:38 a.m. Cairo, 7:10 a.m. Tokyo, 8:16 a.m. Sydney, 10:15 a.m. Auckland on Wednesday.