Supermoon can be viewed tonight

March 19, 2011

By SHEA STASKOWSKI
sdnedu@bellsouth.net

Look to the sky tonight to see the biggest and brightest moon in the last 18 years.
Dubbed “The Supermoon” by astronomers, the nighttime spectacle is getting buzz due to its proximity to the Earth and the fact that it is a full moon.
“The moon has been this close before, but not as a full moon that close,” said James Hill, director of the Rainwater Observatory in French Camp. “The moon goes around the Earth in an elliptical orbit, so it’s closer sometimes than other times, and it just so happens that this time, it will be closer than it has been in years.”
The last full moon so close to the Earth occurred in March of 1993.
In the span of a month, the variation in the size of the moon is due to the elliptical shape of the moon’s orbit. When the moon is at it’s closest to Earth, it is known as a perigee, which is roughly 30,000 miles closer to Earth than it is at it’s further point, known as apogee.
In December 2008, a near-supermoon occured when the moon turned full just four hours before its perigee. But tonight, the full moon and perigee are just under one hour apart, Hill explained, which will make for a more impressive sight.
“When the moon is at it’s further point and nearest point, there is only about a 14 percent difference,” Hill explained, which is why most people don’t take note of the varying sizes of the moon. But the added factor of the full moon will make tonight’s perigee appear much larger and 30 percent brighter, Hill added.
The moon will look especially large as it first rises over the horizon. This is due to an optical illusion called moon illusion, though the moon will be the same size all night.
Though some are speculating that the supermoon is a result of the recent earthquakes in Japan, Hill said there is absolutely no correlation, and that this supermoon is just the natural pattern of the orbit.
In addition to the largest perigee in 18 years, watchers of the sky will have another sight to see. Saturn will come in view tonight for the next several months as Earth begins to approach the distant planet.
“When the full moon rises, right after it, Saturn will be rising,” Hill said. “On March 20, the moon and Saturn will only be eight degrees apart.”
Though Saturn will be visible for several months, Mercury is will only be visible for the next week.
“This weekend is about the best time of year to see Mercury,” Hill said. “If you don’t look for it in the next week, you won’t see it because Mercury moves so quickly in its orbit.”
Roughly 30 minutes after sunset tonight, Hill advises people to look due west.
“You will see two bright stars,” he said. “They will be sort of in the twilight, and the lower one is Jupiter and the one above and just to the right will be Mercury.”
The Rainwater Observatory will be open tonight at 6:30 for those who wish to observe the supermoon through a telescope, though Hill said a telescope isn’t necessary. There is no charge for admission.