Don’t know a perigee from an apogee? Confused between a tire tread and a lunar tetrad? Worry not, we’ve got you covered with my layperson’s primer for Sunday’s big stargazing party in the sky. This weekend, you can witness a celebrated celestial event that won’t be repeated for another 18 years: a rare, blood-tinted supermoon total lunar eclipse. Sounds sinister, and perfectly fitting for the upcoming Halloween season, but it’s really just all a simple matter of planetary dynamics and physics.
On Sunday evening, Sept. 27, at 10:11 PM EST or 7:11 PM PST, the full moon will be bathed in a ruddy, reddish hue as the Earth’s shadow falls over its pale face for one hour and 12 minutes. But what makes this lunar eclipse extra special is that it also coincides with the moon’s perigee, where it'll be at its nearest point to our Big Blue Marble. Sunday night’s eclipse is the fourth and final of the "blood moons," a phrase used to describe the four lunar eclipses we’ve observed in 2014/2015 and scientifically known as a lunar tetrad.
I see you shrugging your shoulders. Well, it’s only happened five times in the last hundred years, and most recently 33 years ago when Ronald Reagan was president and Return of the Jedi was over a year from release. It’s a perfect storm of cosmic proportions you can’t afford to miss: a full moon, paired with a total lunar eclipse, while our lone satellite is in the path of its elliptical orbit closest to Earth. The reddish-copper color that washes over the moon is caused by scattered sunlight filtered through the Earth's atmosphere.
Still unimpressed? Picture me sporting a cascading Camaro-cut mullet and rocking out to Iron Maiden in parachute pants when the last one took place in 1982. See, I knew you’d come around, eventually. And the next time it happens won’t be until 2033, when many of you may be using your AARP cards at Denny’s for a Grand Slam breakfast. Excited now?
The partial eclipse starts at approximately 8:00 p.m. EST, then peaks at around 10:36 p.m. EST, when it enters totality and will be seen in North and South America, as well as Europe, Africa and parts of West Asia. Conditions for the harvest supermoon eclipse should be favorable in most of the northern hemisphere, so break out some moon munchies and frosty beverages, arrange some lawn chairs, call up some friends and impress them with your newfound knowledge of this rare astronomical spectacle.
Enjoy the show and keep watching the skies!