Festive Cinco de Mayo celebrations today will have competition for attention from far, far away. That’s 221,802 miles from Earth, to be exact.
At that distance, the moon will be at perigee – its closest point to Earth in its elliptical orbit – this year. The fact this lunar phenomenon is coinciding with this month’s full moon earns it the title of “super moon” as well as “fat moon.”
Not only will the Earth’s satellite appear larger that evening; it will also shine brighter than usual – about 16 percent – in its full-moon duration that day.
While this may create a stir among astronomy enthusiasts, as well as avid lunar shutterbugs, this heavenly event is actually not as rare as a blue moon which occurs about once every two or three years.
“The moon is in an elliptical orbit, so it periodically comes closer to the earth. Its distance from the earth varies as it orbits around,” explained California State University, Stanislaus astronomy associate professor Christopher De Vries during a telephone interview Thursday.
Perigee – the term used when the moon is at its closest approach to earth – is “not that unusual an occurrence,” he noted.
“When there’s a full moon – that means the sun and the moon are on opposite sides of the earth – when that happens, that has an effect on the tide. But (perigee) is not that unusual. It’s actually interesting,” he said.
Even though the moon on Saturday will be at its closest to earth this year, its size will “not be anything that’s really perceivable” to the naked eye, added De Vries.
“The moon appears to be very large when it appears on the horizon, but that’s an optical illusion,” he further explained. “If you hold a dime and hold it at arm’s length, that should be as big as the moon is.”
What is garnering quite a bit of attention and excitement among astronomers and professionals like De Vries more than the lunar perigee on Saturday is the spectacular solar eclipse coming up on May 20. That’s when the first annular eclipse to occur in the United States in nearly two decades – 18 years to be exact – will take place. The only sad part of it is that you have to be in Alaska and China to have “a great view” of the phenomenon showing the sun turning into a ring of fire as the moon passes right in the middle of the sun creating a ring-of-fire effect, De Vries said. Southern Japan and Korea also will have great views of this eclipse phenomenon.
“But in Central California, we’re only going to see the edge. The farther north you are, you’re going to get a little more of a view “of the eclipse which will start around 5:30 or 6 in the evening until sunset. So I’m looking forward to watching the sunset that evening,” said De Vries.
For those who are planning to view that solar eclipse on May 20, he offers the following advice.
“Don’t look – never look – directly at the sun even if it’s an eclipse, because there’s a tendency to stare at it; you can go blind,” he said.
One thing he recommends people to do for solar-eclipse viewing with the naked eye is to “build a pinhole camera, and you’ll get protection” looking inside the box rather than directly at the sun.
Another alternative for such viewing is to get a hold of a “shade 14 welding glass” utilized by welders on the job, and use that to safely look directly at the sun during the eclipse, De Vries added.
Unfortunately, due to budget constraints, observation nights and events when the public can view lunar or solar phenomena such as the May 20 eclipse on campus courtesy of the university is now a thing of the past. At one time, the university had 81 astronomy events a year that were open to the public, De Vries noted. The last free event he was involved in was over a year ago when more than 500 members of the community attended, recalled De Vries who is the only astronomer on the faculty in the university’s Department of Physics, Physical Science, and Geology.