Next 5 weeks bring rare solar events to Colorado

On the afternoon of Sunday, May 20, Colorado will see a “bite” taken out of the sun as the moon moves across the sun causing a partial solar eclipse. The eclipse starts at 6:22 p.m. with maximum eclipse at 7:30 p.m. and the sun will set at 7:50 p.m.

The celestial event will mark the most complete solar eclipse the U.S. has seen in more than 10 years, according to Douglas Duncan, director of the University of Colorado Boulder’s Fiske Planetarium.

The planetarium will host an eclipse event at Folsom Field on the CU-Boulder campus from 5:30 to 8 p.m. on May 20. The event will include an expo from local space-related agencies and presentations from Fiske Planetarium.

Admission is free for anyone who has already purchased eclipse-watching glasses for $2 at Boulder’s McGuckin Hardware or Fiske Planetarium. Admission on the day of the event is also $2, which includes a pair of eclipse glasses. Supplies are limited and pre-purchase is recommended.

“It is important to safeguard your eyes when observing any solar event,” Duncan said. “If you accidentally looked at the sun on any day your eye would hurt and you would look away. On an eclipse day there is a compelling reason to look at the sun but it is just as powerful, so you must protect your eyes to watch the eclipse. Even if only a fraction of the sun is visible this is still true.”

The inexpensive glasses designed for eclipse viewing are much darker than regular sunglasses, and provide appropriate protection for viewing solar events. For comparison, the same protection is also available from the very darkest type of welder’s eye protection, rated 14 on a 1 through 14 scale.

Fiske Planetarium and Sommers-Bausch Observatory on May 20 will be open from noon until 4 p.m. for “Astronomy Day” celebrations, including fun activities with telescopes and hands-on planetary transit displays. The observatory will stay open until 10 p.m. for continuing telescope observations after dark.

A little more than two weeks later, on the afternoon of Tuesday, June 5, the planet Venus will cross in front of the sun. This rare crossing — called a solar transit — won’t be seen again for a century.

“Even though Venus is as large as Earth, it is only 1 percent the size of the sun, so it will look like a tiny dot,” said Duncan. “In the past, astronomers sailed all over the world to watch transits. If you could see Venus from two widely separated sites its position would be slightly different and by using geometry you could find out the size of the solar system.”

The glasses used to protect eyesight while watching the solar eclipse also will provide protection when viewing the solar transit, Duncan said.

More information on preparing for eclipse watching, the solar transit and the special protective viewing glasses can be found on the Fiske Planetarium website at

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