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Smallest planet makes big move
Space buffs, curious gazers peer though big telescopes to witness Mercury's transit
By Allison Bailey
abaile19@mscd.edu

Photo by Jenn LeBlanc • jkerriga@mscd.edu George Hammond, a professor of physics and astronomy at UCD, looks through his telescope, which he bought specifically to see Mercury’s transit.

A crowd of people gathered on the lawn near the flagpole on Nov. 8 and peered through telescopes to watch an astronomical event that happens only once every ten years.

Seven telescopes were made available, and behind each one a long line of people waited to have a look at the transit of Mercury in front of the sun. Each telescope was manned by a volunteer to help explain the event.

“It’s really nice, actually,” said Alex Nguyen, a Metro physics major. “I didn’t think it would be that small compared to the sun.”

Metro graduate Stephanie Pahl helped organize the viewing with the Metro and UCD physics departments and the Society of Physics Students.

Pahl said the number of people interested in watching Mercury surprised her.

“We estimate that between 700 and 1,000 people came,” Pahl said. “We were very surprised. We had no idea that so many people would be interested in astronomy.”

Mercury passes in front of, or transits, the sun about once every 10 years. That makes it a rare event by human standards, but in astronomical terms it’s a frequent event, said Grant Dean, a physics professor at Metro. Dean was volunteering at a reflecting telescope, which reflects the light of the sun off a spherical mirror and projects it onto a metal plate.

“Most of the time Mercury passes north or south of the sun because its orbit is tilted compared to the Earth’s,” Dean said. “You need a nice cushy alignment between the Earth and the sun (in order to see the transit).”

According to NASA’s website, a Mercury transit takes place 13 times a century. Documented on NASA’s website are all Mercury transits since 1605. Between 1605 and the most recent transit on Nov. 8, Mercury has transited the sun 56 times. Also, NASA has estimated to the minute all the times Mercury will transit the sun up until the year 2295, which is another 38 times. The last time Mercury transited the sun on Nov. 8 was in 1881.

Pahl saw Mercury transit in 1999 while working at the Denver Museum of Nature and Science.

“I thought the event was so incredible that I really wanted to watch it again, and I thought it would be fun to include other people,” she said.

According to Pahl, most of the telescopes used belong to the Metro Physics department, but three were her own. They all had to be equipped with special filters to enable people to look at the sun without damaging their eyes.

One of the telescopes belonged to Frank Saunders, a scientist with the Boulder Department of Commerce, who was there to talk to participants about astronomy and support science education, he said.

Saunders’ telescope was equipped with a hydrogen-alpha filter, which isolates a certain spectrum of light that makes solar flares visible. People looking through his telescope were able to observe the Mercury transit, a sunspot and a solar flare.

“We have kind of a triple feature at the moment,” he said.

Saunders said that before the invention of radar, transits of Mercury and Venus used to be very important to astronomers who wanted to determine the distance between the Earth and the sun.

“What I like about seeing a transit like this is being able to introduce people to an aspect of astronomy. It gives us a chance to see the size of a planet compared to the sun,” Saunders said. “It should remind us for a moment just how tiny our planet really is.”