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Transit of Venus Online: Your Comprehensive Guide, and Yes There’s an App for That

Transit of Venus occurs today, and ICTMN brings readers a list of the best sites to get more information from.
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It’s almost time! Today’s the big day, when Venus passes between Mother Earth and the sun in a unique alignment of the two planets with their star.

Venus is about to transit the sun in the second of this century’s pairings of the phenomenon that happens when the orbits of Mother Earth and the solar system’s second planet are on the same plane. Normally that of Venus is slightly inclined relative to Earth’s, but about once every 105 years or more they line up, and then eight years apart the transit occurs. Because this is the second of the pairing, it will not be seen again until 2117.

Venus will begin wowing viewers just after 6 p.m. Eastern Daylight Time and continue past sunset. People east of the International Dateline will see it as the sun rises. Some lucky viewers, such as those in Hawaii, will be able to watch the entire transit, starting about noon. Indeed, of the many places hosting viewings and parties, both online and off, the observatories on Hawaii are among the busiest. That includes NASA’s observatory, which will broadcast the event viewed through massive telescopes.

Why is everyone so excited? Partly because measuring Venus’s transit is key to measuring the size of the solar system, and partly because it is a rare and novel thing to behold. Numerous websites are devoted to helping people learn about and witness this celestial happening. Below are the most informative and reliable links, culled from the huge quantity of information that has cropped up in recent months.

Different indigenous cultures have varying reactions to stellar phenomena. Many Navajo, for example, did not watch the recent annular solar eclipse of the sun in May because of a taboo. The ancient Mayans venerated Venus but were a little afraid of this morning and evening star. They tracked its path through the skies assiduously and used it to determine the best times to wage war.

At this point many of the sites devoted to this once-in-a-lifetime phenomenon have been taken over by blank screens at the ready, and countdown information. But they are still chock-full of info. Here are some of the most reliable sites, and what they can tell us about this astronomical wonder.

Sun Earth Day is a site put up by NASA to inform, broadcast and otherwise chronicle the major sun-related skywatching events of any given year. The annular eclipse of May 20 was one, but now that that’s over, the site is completely focused on the transit of Venus. It is also where one can watch the transit webcast from the summit of Mauna Kea, Hawaii.

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The site includes an interactive map that helps you locate a viewing party near you, if you are not content to watch online.

NASA Headquarters. From NASA itself we have astronomer Fred Espanak with a page about the transit, describing and illustrating in great detail what the transit will look like and what time to catch the best look. is devoted completely and unequivocally to, well, the famous transit. Do not confuse it with, which is about the 2004 transit and thus does not contain the most current information. has extensive coverage as well, focusing on the history, what the measurements of the transit can tell us, and all other facets of this phenomenon.

Sky and Telescopemagazine published a comprehensive overview, with timetables.

Transit of Venus Projectis a site run by Astronomers Without Borders, a group of scientists and astronomers based in California, with membership worldwide, that focuses on uniting everyone under the common sky.

Lastly, thanks to the Transit of Venus Project, observers themselves can be sources of information as well. There is, of course, an app for that. Scientists are urging armchair astronomers to download it and send their observations of the transit to a global center that will use the information to measure the size of the solar system. It’s free, and fun. Download it here.