Although I know that I will not be the only one from Astro 17 to post about this Sunday's supermoon, I wanted to look a bit more into the phenomenon that brought millions of people outside to stare at the moon for a few hours.
At around 10:11 (ET) on Sunday night, the full moon was shaded a dark red and looked incredibly prominent in the sky. The moon will be fantastic due to a number of terrific coincidences, the first of which is a full lunar eclipse. In the lunar eclipse, the Earth will be directly between the sun and moon meaning that there will be no direct sunlight hitting the moon, the usual cause of its shine in the night sky. Instead of its usual white shine, the moon on Sunday had a dark red tint, due to Rayleigh Scattering, the same effect that causes the sky to look blue. Basically the low amounts of light particles that do reflect off of the Earth and hit the moon will be scattered by the particles of the atmosphere only allowing certain wavelengths to continue moving an assigned path. In this case, a lot of the red light will be reflected off the moon, giving it the "Blood Moon" effect that we saw on Sunday night.
The reason the September 27 caused such a stir throughout the world was because it combined a total lunar eclipse, the 4th of the year, and the moon at its perigee, or the closest that it will ever be to the Earth. Because the Moon's orbit is elliptical, it has a furthest (apogee) and closest (perigee) approach to Earth. The moon passes through its apogee about once a month. During this pass through, the moon looks 14% larger and 30% brighter than it does at its pedigree. However because this occurrence and a full lunar eclipse do not happen too frequently, the chances of them falling on the same night is extremely rare. In fact, the phenomenon, called a Saros, only happens every 18 years, 11 days and 8 hours.
Luckily, due to the rotation of the Earth and moon as well as weather patterns, the Boston area was one of the top sights to see the super moon. It was really refreshing to walk back to my dorm in Currier and see hundreds of students and faculty standing in the quad lawn just gazing up at the sky in silence. While it may not be as evident as it is to us, the students who choose to take an astronomy class, the night sky is pretty captivating. Hopefully this inspires people to take some time to appreciate the stars a bit more often. Or maybe it will take another 18 years to get people looking up.
Sources:
http://www.space.com/11161-supermoon-full-moon-science-infographic.html
http://www.timeanddate.com/astronomy/moon/lunar-perigee-apogee.html
http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/blusky.html#c2
http://www.foxnews.com/science/2015/09/27/sundays-rare-supermoon-eclipse-what-need-to-know/
http://images.latinpost.com/data/images/full/53810/mexic-moon-mission.jpg?w=600
Great post, Simon! I'm glad you got to enjoy the supermoon this year! 5/5
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