Three Crescents and a Sinking Comet

If you're crazy about crescents, you'll find your happy place this week between the Moon and Venus. Meanwhile, we shift our focus from 45P/H-M-P to another famous periodic comet, 2P/Encke.

What makes a crescent special? Is it the contrast of pointed horns and bowed arc or simply the Moon's fragile appearance that's so breathtaking? If I could find the bumper sticker, I'd happily slap I Brake For Crescents on the back of my car.

Late February crescendos with crescents — two brought to us by the Moon and one via Venus. On Friday morning, February 24th, face southeast about 40 minutes before sunrise to spy a sliver Moon not two days from new with its back to the Sun. Low altitude may color the crescent peach, adding to the beauty of the sight.

Three nights later on February 27th, watch for an even thinner Moon to materialize low in the western sky less than a day and a half past new, horns pointed up and ready to charge into the night like a Pamplona bull.

In late February, the ecliptic arcs sharply up and away from the western horizon, which gives the Moon a swift kick into the evening sky and makes sighting the young crescent easy work.

Since phases of the Moon and the Earth — as seen from the Moon — are complementary, a sickle Moon implies a nearly full Earth for an astronaut staring back in our direction. Earth, being nearly four times as large as the Moon appears in our sky, reflects a great deal of sunlight back at the Moon, lighting up the remainder of the lunar disk in an ember-like luminescence called earthshine. Earthshine is most obvious when the Moon mimics that Mona Lisa smile.

Venus throws its scimitar in the ring, too! Since greatest eastern elongation in mid-January, Venus has been slimming down while also growing in apparent size as it approaches inferior conjunction on March 25th. Currently a banana-thick crescent measuring 43″ from tip to toe, the planet is large enough to show a shape in any telescope, even 10× binoculars.

The crescent will become larger and strikingly thinner in the coming weeks, so be sure to keep an eye on it. Just like the Moon, the Venusian crescent will flip from one side of the planet to the opposite when it reappears west of the Sun in the morning sky in late March.

Now that I've dragged you by the horns this far, you'll be happy to know there's more than one reasonably bright evening comet vying for your attention. We've been tracking 45P/Honda-Mrkos-Pajdusakova for the past couple weeks, and while it's still just visible in binoculars and now sports a short tail, periodic comet 2P/Encke has been slowly brightening at the same time. Pity it's only now reaching magnitude +9 and soon will be departing the evening sky.

As I write this, the comet is cozying up to Venus in Pisces, a compact fuzzy glow of magnitude +8.8. It's brightening as it runs westward toward the Sun and will reach perihelion on March 10th. Comet 2P/Encke could become as bright as magnitude +6.5 in the next 10 days and become visible in binoculars shortly before disappearing in the solar glow around March 6th. The best time to catch it is near the end of evening twilight. On February 27th, the thin lunar crescent and Venus will neatly frame the comet. Photos anyone?

For northern hemisphere observers, that's all she wrote, but southern skywatchers will have another go at 2P/Encke when it returns to the morning sky in late March at magnitude +8 and fading.

And of course don't forget 45P/Honda-Mrkos-Pajdusakova. Now that it's become well placed in a moonless sky, amateur astronomers have been having better luck recording new details, including a fresh, new tail. The photo above, taken by José J. Chambó, perfectly captures the comet's ethereal beauty in the context of deep space.