UND astronomers webcast rare solar eclipse Sunday, May 20


Juan Pedraza

Document Type


Publication Date



UND astronomers webcast rare solar eclipse Sunday, May 20

A popular University of North Dakota eclipse-chasing team is in California to capture a rare and glorious "ring of fire" solar event. With clear, calm weather forecast for Sunday afternoon, the team expects excellent viewing.

"The National Weather Service is predicting a perfect day for us out here," said Tim Young, an astrophysicist in the UND Department of Physics and Astrophysics and globally recognized eclipse observer.

With his longtime eclipse teammate Ron Marsh, professor and chair of UND Computer Science, Young expects to share the event with the world via streamed images over the Internet.

The UND scientists arrived at Redding, Calif., Wednesday to start setting up for Sunday's solar show. The eclipse is set to begin around 5:15 p.m. Pacific Daylight Time (7:15 p.m. Central Daylight Time), when the Moon begins to cross the Sun. The Moon will be over the Sun for about eight minutes. The event ends 7:36 p.m. Pacific (9:36 Central) when the Moon is fully past the Sun.

"We're capturing the images live with the telescopes through a solar filter, because it's very dangerous to observe these solar events directly," said Young, noting that this is the fourth annular eclipse he and Marsh recorded and Webcast for UND.

"The images of the eclipse—filmed through a filter as they happen--will be projected on a large screen, and that's what we'll be showing on our Webcast," Young said. "For me as an astrophysicist, the important thing is that events such as eclipses allow us to confirm the accuracy of our measurements and predictions for such celestial events."

While the public is largely concerned with time in minutes, scientists such as Young measure these events down to fractions of seconds. Young and his team record these events for both classroom use at UND and for educational outreach at schools in the Grand Forks area and beyond.

Young and Marsh will capture the solar eclipse action with two refracting telescopes: a 70 mm Ranger and an 80 mm Orion. The size, or aperture, in millimeters refers to diameter of the objective, or main, lens and measures the telescope's light-gathering capability. Refracting means a tubular telescope that uses its main lens to magnify an image directly through the eyepiece, without any convex mirrors or prisms (a small mirror can be used at viewing end to reflect the image up into a viewing eyepiece).

The UND team is collaborating with Shasta Community College to host a public viewing and live Webcast of the eclipse.

"We've been waiting for this one for a long time," said Young. "The last one seen in this country was in 1994 (annular); the next solar eclipse—a total eclipse—won't come until 2017."

About annular eclipses

Both total and annular solar eclipses are among nature's most magnificent sights.

"An annular eclipse is unusual because the Moon is a little bit further in its orbit around the Earth," Young said. "This means that the apparent disk of the moon is smaller and when lined up with the sun it is smaller. It is very similar to holding a dime and a nickel together with their centers aligned. The edge of the nickel is seen all around on the outside."

The sun is the nickel and the moon is the dime in this model.

"Some of the US (western/middle part) will see a partial eclipse," Young said. "The sunlight will still be streaming around the edge of the moon and even at 99 percent covered, and it's very dangerous unless you have eye protection. This usually is referred to as the 'ring of fire' and produces a glowing ring that looks like a giant eye in the sky with a dilated pupil. The most populous cities in the path of totality – 80 miles across – will be Redding, Calif., and Reno, Nevada, with Salt Lake City, Utah, and Amarillo, Texas, getting the eclipse as the sun sets."

The UND Eclipse Team is in Redding, Calif., to get the all four contacts of the eclipse (entrance and exit of the moon).

The reason that eclipses are so rare is because the moon's orbit is tilted five degrees from the ecliptic (the Earth-sun plane). That leaves only two points where the sun, Earth and moon can line up exactly.

The Moon is nearly the same angular size as the Sun (from our perspective, the Moon's disc looks about the same size as the Sun, even though in reality the Sun is 400 times bigger the Moon and 400 times farther away. So the Moon in a total eclipse can block out the Sun over a 200-mile wide path that sweeps across half the Earth.

The UND eclipse team's first eclipse Webcast was from Anatolia, Turkey, on March 26, 2006. The team's efforts are extremely interactive through use of its chat room, audio question/answer system, podcasts, and blogs.

Juan Pedraza

University Relations Writer/Editor

This document is currently not available here.