Looking Up: Won't You Be My Neighbor?

Feb 18, 2019

Credit M. Procell

Hal is 'over the moon' in bringing us this week's episode of Looking Up.

One object I never tire of is our old, dependable Moon. I really love the Moon, and I love to explore the mountains, ridges, and craters through my telescopes.

But when the Moon is full and at its brightest, it is pretty hard to observe with a scope, and it can be just too bright. So tonight, and tomorrow night when the Moon becomes the second so-called “super-moons” of 2019 (meaning it’s a wee bit closer than normal), take a look instead at the neighborhood the Moon is hanging out in. If you look carefully, tonight, you’ll see the full Moon just above the bright star Regulus in the constellation Leo the Lion. If you look at the same time tomorrow night, you’ll see that the Moon appears to be just below Regulus – how the heck did that happen? Well, the Moon is so close to us that it moves across the sky, as you’ve no-doubt seen, over the course of roughly a month. Hey, I bet that’s where the word “month” comes from! In fact, Regulus is almost exactly on the line in the sky, called the ecliptic, so from time to time, the Moon and various planets cross in front of, or occult, Regulus. In 2044, the planet Venus will turn that trick and block out Regulus for a moment. You don’t see that too often, not even in a moo-nth of Sundays! 

Regulus is hotter than the sun, about 69 light-years distant, and shines in Earth's skies as the brightest star in the constellation Leo, the Lion. The Moon is the brightest object in the night sky and is less than 1.5 light-seconds away. As illustrated in this multiple-exposure photograph, such lunar occultations of bright stars can be majestic to watch. Their exact timing depends on the observer's location but they are not particularly rare occurrences.
Credit Joe Orman (8/2/1999) / nasa.gov

If you’d like to take a closer look at the Moon, or any of the other wonderful and amazing things in the sky, please visit csastro.org for a link to information on our monthly meetings and our free public star parties.