In Recent Astronomical News: Lunar Eclipse

If you were on campus (or in western Africa, western Europe, or anywhere in the Americas that isn’t Alaska or northwestern Canada) the night of August 27, you might have been out walking, or glanced out your window, and noticed that the moon looked different than usual. Around 7:30 or 8pm, it might have looked a bit darker than normal, standing out a little less against the night sky. Closer to 9pm, the sky might have appeared to be changing color, trying on Reed’s signature shade of red. After approximately 9:12pm, it might have begun to lighten and revert back to its typical gray. By midnight, you might have questioned if anything had happened at all.

This kind of astronomical event is referred to as a lunar eclipse. Lunar eclipses occur when the Earth is positioned perfectly between the moon and the sun so that the shadow of the Earth falls on the moon’s surface. This phenomenon is why the moon appears darker during a lunar eclipse. As to why the moon appears red, it’s slightly more complicated, and has to do with the different colors that make up sunlight. Colors with shorter wavelengths, like blues and violets, scatter more easily when they pass through Earth’s atmosphere, as opposed to colors with longer wavelengths, like oranges and reds. During a lunar eclipse, colors with longer wavelengths are able to make it through Earth’s atmosphere and reach the surface of the moon. If you were to stand on the surface of the moon during a lunar eclipse, you’d see exactly what we see on Earth during a solar eclipse: the sun obscured by a black disc, save for a glowing, oscillating orange ring. 

While eclipses occur four to seven times per year on average, this particular lunar eclipse was a part of the Saros 138 series. For the etymology nerds out there, “Saros” comes from the ancient Greek noun “saro”, which in turn comes from either the Babylonian word “saru,” meaning “3600,” or the ancient Greek verb “saro,” meaning “to sweep.” Eclipses within a saros series occur every eighteen years, eleven days, and eight hours (6,585.3 days) apart. Therefore, the last eclipse of the Saros 138 series occurred on August 16, 2008, and the next one will occur on September 7, 2044. All eclipses in the Saros 138 series share two characteristics: they happen when the moon is at its north node—which is one of two locations where it crosses the Sun’s path—and from that north node, the moon moves southward. The duration of the Saros 138 series is 1,460.44 years (1,460 years, five months, and around eight days, to be precise). It began on October 15, 1521, and it will end on March 30, 2892. 1521 was the year in which Martin Luther was excommunicated by Pope Leo X. To the human perspective, this might seem like an extraordinarily long time ago, but if you were to scale the centuries against the entire history of the universe, it is in fact very, very recent (check out Carl Sagan’s cosmic calendar). There is not yet any historical data for the year 2892, but someone on Quora predicts that we’ll have accomplished world peace. Someone else predicts that we’ll have evolved into cyborgs and another person predicts that the technology we’ve developed will destroy us as a species. Who can say?

All this to say, don’t be worried if you missed August’s lunar eclipse. While it was the last lunar eclipse this year, there will be  three next year, on February 20, July 18, and August 16. Only the lunar eclipse on August 16 is visible from Reed College, but the February 20 eclipse can be viewed from nearly everywhere else on the plane —mark your calendars if you’re studying abroad in South America, Africa, Europe, or Asia. Similarly, if you spend your summers in Oceania, Asia, the western coast of Africa, or adventuring around Antarctica, mark your calendar for the July 18th eclipse. And, for whatever reason, if you happen to find solar eclipses more interesting than lunar eclipses, there will be two of those next year as well, on February 6 and August 2. The February 6th eclipse will be annular rather than total, and visible from South America (save for Ecuador, Colombia, and Venezuela) and western Africa, as well as Antarctica. The August 2 eclipse can be viewed in totality from Algeria, British Indian Ocean Territory, Egypt, Gibraltar, Libya, Morocco, Saudi Arabia, Somalia, Spain, Sudan, Tunisia, and Yemen.

Sources for this article were taken from NASA, TimeandDate.com, Wikipedia, and (most importantly, Quora.