2008 Woodie Awards
Mercury pays rare visit
Astronomy department views Mercury crossing sun
Mark Freeman
Issue date: 11/14/06 Section: News
|
Dr. Ron Olowin, chair of the physics and astronomy department, helped students and other curious onlookers observe the event through a large telescope on the Chapel Lawn. Olowin explained that the event is "fairly rare because there are only about thirteen of these transits every century" and that it is a "once in a lifetime experience."
According to Olowin, the orbits of Mercury and Earth are "not compatible" since they rarely align with each other. Mercury has a faster orbit than Earth, and one Mercury year is roughly 88 days. Olowin compares the orbits to car blinkers-sometimes people will have their lights flashing at the same time, but at other points the lights won't be in sync.
Saint Mary's students were lucky as they were able to see the planet's entire five-hour trek across the sun. "In the East Coast, people only saw it for a few minutes," Olowin said.
A special filter was used to view the sun. Olowin explained that the filter "absorbs or reflects 99.9 percent of the light that strikes it," and whatever remains is pushed into a magnifier. This way, people can view the sun without worrying about being blinded.
Those who took a glimpse through the telescope saw the planet as a tiny speck against the massive surface of the sun. At different points in the day viewers could watch the planet slowly progress across the star until it finally vanished from sight. Along with Mercury's transit, students were also able to view a large sunspot about ten times larger than Earth through the telescope.
A simulation of Mercury crossing the sun can also be viewed on the department's website (http://physics.stmarys-ca.edu/) in the Astronomy Lab section. This allows students to see Mercury's transit all at once, instead of over the course of a few hours.
The department has put on events like this before. "We often observe the November meteor showers as well as lunar eclipses and partial eclipses of the sun," said Olowin. They have watched a transit of Venus crossing the sun as well, an event that happens roughly twice each century. While astronomy classes will still be looking at the stars and other exotic objects like quasars, Olowin thinks that there won't be another public event until next term.
For the Mercury viewing, the department had hoped to connect a television camera to a telescope, allowing for live television broadcast of Mercury's transit, but a power failure in the morning damaged some equipment. "We weren't able to resurrect the camera," Olowin said. There were worries that the project might be cancelled due to rain and bad weather, but the skies cleared up in the afternoon.
Unfortunately for those who missed the event, the next Mercury transit won't occur until 2016, according to NASA, and it most likely won't be as majestic as the one from last Wednesday. Because of the latitude and longitude of the planet in the sky, "We won't see anything like this until 2170," said Olowin.