Archive
Ephemeris: 04/08/2025 – A look at Proxima Centauri
This is Ephemeris for Tuesday, April 8th. Today the Sun will be up for 13 hours and 9 minutes, setting at 8:19, and it will rise tomorrow at 7:08. The Moon, halfway from first quarter to full, will set at 5:57 tomorrow morning.
The nearest star to our Sun is a triple star system called Alpha Centauri or Rigil Kentaurus. It is in the skies of the Southern Hemisphere, but visible from the far southern parts of the United States. I’ve seen it from the Florida Keys and also from the latitude of the Big Island of Hawai’i. The closest member of that group this is a star we call Proxima Centauri or just Proxima for short. It is not visible to the naked eye. It is a red dwarf star maybe 12% the Sun’s mass, and at 11th magnitude. Proxima would be tough to spot with a pair of binoculars in a region of the sky which is filled with stars because it’s in the band of the Milky Way. Alpha Centauri, itself, is located near the Southern Cross, the farthest of the two bright stars to the east of it.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). Times will be different for other locations.
Addendum
07/03/2023 – Ephemeris – The Sun is more massive than most stars
This is Bob Moler with Ephemeris for Monday, July 3rd. Today the Sun will be up for 15 hours and 29 minutes, setting at 9:31, and it will rise tomorrow at 6:02. The Moon, at full today, will rise at 10:28 this evening.
The Sun appears to be a singular object in the sky. There is none other. But is that true? No, it’s not. The Sun is a star, middle-aged for a star of its mass. The Sun is bigger than most stars, because most stars are runty red dwarf stars. In fact the closest star to our Sun is a red dwarf, called Proxima Centauri, the third, outlying star in the triple star system whose brightest star is called Rigil Kentaurus, though better known by its 1603 Bayer catalog designation, Alpha Centauri. Proxima is a challenge to spot even with binoculars. It turns out that stars visible to the naked eye are all brighter than the Sun. As far as the range of stellar masses go, the Sun is pretty much in the middle. Rigil Kentaurus itself is 8 percent more massive than the Sun and 50 percent brighter. Both Rigil Kentaurus and Proxima are too far south to see from Michigan.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT –4 hours). They may be different for your location.
Addendum
Bob Moler's Ephemeris Blog 