Wednesday, March 16
Whether you’re up early or late today, there’s a tempting target in the north: the variable star Delta (δ) Cephei in Cepheus the King. This bright star sits roughly 2.5° east of Zeta Cephei, which marks the lower righthand (southeastern) corner of the house-shaped constellation.
Delta Cep is the archetypical Cepheid variable star — a supergiant star no longer fueled by hydrogen, which has already been exhausted from its core. Now pulsating in size, as a result Delta Cep changes brightness regularly over a period of 5 days, 8 hours, 47 minutes, and 32 seconds, swinging from magnitude 3.48 at its brightest to 4.37 at its dimmest. Take some time while examining the star tonight to compare it to nearby suns. Come back every few days and you may be able to tell whether it’s currently brightening or dimming. Astrophotographers with experience using photometry software can easily chart the star’s brightness over time, plotting it out as a light curve.
Sunrise: 7:10 A.M.
Sunset: 7:08 P.M.
Moonrise: 5:32 P.M.
Moonset: 6:44 A.M.
Moon Phase: Waxing gibbous (97%)
Thursday, March 17
When you think of star clusters in Cancer, M44 — also called the Beehive Cluster — likely 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 4th-magnitude 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. That’s just bright enough to see with the naked eye, but only on a moonless night with otherwise dark skies. Given the bright, nearly Full Moon today, you’ll want binoculars or a telescope to aid in your search. This beautiful, dense grouping of stars is some 4 billion years old — pretty old for an open cluster, and astronomers expect it may last 5 billion years more before it disperses completely.
Sunrise: 7:08 A.M.
Sunset: 7:09 P.M.
Moonrise: 6:38 P.M.
Moonset: 7:11 A.M.
Moon Phase: Waxing gibbous (99%)
Friday, March 18
Full Moon occurs at 3:18 A.M. EDT, casting its bright light across the predawn sky. It will do the same this evening, rising around sunset. The March Full Moon is also called the Worm Moon.
This month, the Full Moon sits in Virgo. To reduce our satellite’s effect on deep-sky observing, let’s look elsewhere tonight: Turn north after sunset to find the constellation Camelopardalis. Here, we’re looking for the relatively bright (magnitude 8.5) galaxy NGC 2403. This distant spiral sits nearly 10 million light-years away and spans about 25.5′ by 13′ on the sky. While visible in 10×50 binoculars under dark skies, you’re better off using a telescope tonight to offset the Moon’s interference.
NGC 2403 is located in the southeastern portion of the constellation, close to the tip of nearby Ursa Major’s nose, marked by the 3rd-magnitude star Muscida. From that star, look 7.7° northwest to land on NGC 2403, which sits 0.7° south of a 7th-magnitude field star, HIP 37196.
Sunrise: 7:07 A.M.
Sunset: 7:10 P.M.
Moonrise: 7:47 P.M.
Moonset: 7:36 A.M.
Moon Phase: Full
The Sky This Week: Venus and Mars dazzle before dawn
Source: Trending Update Article
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