Come one, come all to the Venus sky show! The rare event will be visible in the late afternoon on Tuesday in the Western Hemisphere—or Wednesday morning in the Eastern Hemisphere. It is a show you likely have never seen before and will never see again. It’s called the “transit of Venus.” Transit means to pass through or across. During Venus’s upcoming transit, the planet will appear to be a little black dot drifting slowly across the face of the sun. It's a spectacle that won’t happen again for another 105 years.
The event is so unique that museums and schools around the world are holding Venus viewing parties for those who want to see the sun with a temporary beauty mark. Even astronauts aboard the International Space Station are planning to watch the event.
"Anything silhouetted on the sun looks interesting,” said Anthony Cook, an astronomer at the Griffith Observatory, in Los Angeles, California. “Seeing Venus is extremely rare.”
Venus is the second planet from the sun between Mercury and Earth. It is about the same size as Earth. Venus appears as one of the brightest objects in the night sky because its thick clouds reflect a lot of sunlight back into space. But this transit won’t cause a big change to the brightness of the sky. Venus will only block out a tiny part of the sun. "You have to know it's happening," said David DeVorkin, of the Smithsonian's National Air and Space Museum, in Washington, D.C.
The transit will last six hours and 40 minutes. Many people are expected to visit the observatory in Mount Hollywood, in Los Angeles. They will look through telescopes with special filters. Experts remind viewers to have patience. The event takes longer to happen than a solar or lunar eclipse.
Unlike eclipses, Venus transits are truly rare. They come in pairs with each transit separated by eight years. Each pair is separated by more than 100 years. The last transit occurred in 2004. After this year, the next pair will occur in 2117 and 2125. Many of us alive today will not get to see this event happen ever again.
Getting A Glimpse
German astronomer Johannes Kepler first predicted the Venus transit in the 17th century. He observed that every century or so, the orbit of Earth and Venus line up perfectly with the sun. Only six transits have been observed in history. Only two people were said to have seen the transit of 1639. The 1882 transit was more popular. People jammed the sidewalks of New York City and paid 10 cents each to peek through a telescope.
The most recent transit, which happened in 2004, was viewed by millions in person and online. The Venus viewings are important to scientists. They use the alignment of Venus and the Sun to help measure the size of our solar system. The method is still used today to search for alien worlds outside of our solar system.
The entire transit will be visible from the western Pacific, eastern Asia and eastern Australia. Sky watchers in parts of the Western Hemisphere, including the U.S., will see the beginning of the show before sunset. In parts of the Eastern Hemisphere, the tail end of the transit can be seen after sunrise. The event will also be streamed live on the NASA website.
Skygazers who want the full experience are heading to Hawaii. It is the best viewing spot because Venus’s whole transit will be visible. Across the Hawaiian Islands, eclipse glasses will be passed out so that people can safely see Venus crossing without damaging their eyes. Experts warn sky watchers not to stare directly at the sun. As with a solar eclipse, it is important to wear special protective glasses to view the event safely.