The moon is making its closest approach of the year this week
The moon will be rising before 5 p.m. Tuesday and Wednesdays and will be more than evident not long after nightfall.
What will be the second in a sequence of “supermoons” will dominate the night skies over Philly this week and be a high point in a lunar festival that began last month.
Granted, to astronomers and other night-sky gourmets, a supermoon may be the equivalent of a frozen hamburger patty.
But for those who live under the light-compromised skies of Philly and the rest of the Northeast corridor, it would qualify as a star attraction.
This one is notable because the moon will be making its closest approach of the year. At the instant of fullness, at 8:19 a.m. Wednesday in Philadelphia — this time thing may take some getting used to — NASA estimates that it will be 221,800 miles away.
It will appear about 14% brighter than it does when it’s farthest from Earth, with the Sea of Tranquility and the Copernicus Crater about as visible as they get to the unaided eye.
Plus, it will be arcing high in the sky — the lower the sun, the higher the moon — and beaming its silvery light on the remnants of the foliage.
The moon will be rising early enough Tuesday, at 4:07 p.m., and Wednesday, at 4:42 p.m., to be visible not long after nightfall, looming large on the eastern horizon.
In fact, the moon should be casting its light even as some voters are casting their ballots before the polls close Tuesday night.
What is a ‘supermoon?’
Astronomers tend to have a certain disdain for the term supermoon, which actually was minted by an astrologer, says Harry J. Augensen, retired Widener University astronomy and physics professor and now director of the school’s observatory.
“Astronomers prefer the term full moon at perigee,” he added.
A generally accepted definition of a supermoon is a full moon that is in the 90th percentile of the moon’s annual closest approach to Earth of the year.
When are the dates of the next supermoons?
The moon won’t be quite as close, but it would meet the standard for super on Dec. 4 and again on Jan. 3, 2026. (Too early to know if it would be shining on snow.)
Is it true that Earth now has two moons?
No. That report last month was a media/social media hallucination.
The object in question was basically a space rock detected by an ultra-powered telescope in Hawaii. It is not orbiting earth, but moving parallel with it; nor is it visible, unless you have access to something like that Hawaii telescope, nor is it having any effects on our lives.
It evidently has been around about 60 years and looks to hang around 120 more, said Karen Masters, physics and astronomy professor at Haverford College, “a long time on human timescales, but tiny in astronomical timescales.”
“I take it as a nice reminder we live in a dynamical solar system.”
Besides, this week one moon should be enough.