The sky this week from March 11 to 18

Wednesday March 16
Whether you rise early or late today, there is a tempting target in the north: the variable star Delta (δ) Cephei in Cepheus the King. This bright star lies about 2.5° east of Zeta Cephei, which marks the lower right (southeast) corner of the house-shaped constellation.

Delta Cep is the archetype of the Cepheid variable star – a supergiant star that is no longer fueled by hydrogen, which has already been depleted from its core. Now pulsating in size, Delta Cep steadily changes in brightness over a period of 5 days, 8 hours, 47 minutes and 32 seconds, going from magnitude 3.48 at its peak to 4.37 at its peak. Take the time to examine the star tonight to compare it to nearby suns. Check back every few days and you may be able to tell if it is currently brightening or darkening. Astrophotographers experienced in using photometry software can easily plot the star’s luminosity over time, by plotting it as a light curve.

Sunrise: 7:10 a.m.
Sunset: 7:08 p.m.
Moonrise: 5:32 p.m.
Moon setting: 06:44
Moon phase: Waxing Gibber (97%)

Thursday March 17
When you think of the Cancer star clusters, M44 – also known as the Beehive Cluster – probably comes to mind. But that’s not all the crab has to offer. Tonight, let’s enjoy a different open cluster: M67, which spans 30′ near magnitude 4 Acubens, the constellation’s alpha star.

From Acubens, look 1.7° due west and you’ll land right in the middle of M67, which shines at 6th magnitude. This is fair bright enough to be seen with the naked eye, but only on a moonless night with an otherwise dark sky. Given the brightness of the full moon today, you will need binoculars or a telescope to help you in your search. This beautiful, dense group of stars is around 4 billion years old – quite old for an open cluster, and astronomers expect it to last another 5 billion years before fully dispersing.

Sunrise: 7:08
Sunset: 7:09 p.m.
Moonrise: 6:38 p.m.
Moon setting: 7:11
Moon phase: Waxing Gibber (99%)

Friday 18th March
The full moon occurs at 3:18 a.m. EDT, casting its bright light across the predawn sky. It will do the same tonight, rising towards sunset. The March Full Moon is also called the Worm Moon.

This month, the Full Moon is in Virgo. To reduce the effect of our satellite on deep sky observation, let’s look elsewhere tonight: Turn north after sunset to find the constellation Camelopardalis. Here we are looking for the relatively bright galaxy NGC 2403 (magnitude 8.5). This distant spiral is nearly 10 million light-years away and extends approximately 25.5 feet by 13 feet into the sky. Although visible in 10×50 binoculars under dark skies, you better use a telescope tonight to compensate for interference from the Moon.

NGC 2403 is located in the southeastern part of the constellation, near the tip of the nose of nearby Ursa Major, marked by the 3rd magnitude star Muscida. From this star, look 7.7° northwest to land on NGC 2403, which lies 0.7° south of a 7th magnitude field star, HIP 37196.

Sunrise: 7:07
Sunset: 7:10 p.m.
Moonrise: 7:47 p.m.
Moon setting: 7:36
Moon phase: Full

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