Stellar Brightness

The Brightest Stars, as Seen from the Earth

Rank	Popular Name	Name, Constellation	Apparent	Absolute	Distance
						Magnitude	Magnitude	(parsecs)
									(1 pc=3.26 lightyears) 
0	Sun				      -26.8		+4.75		0.000003 
1	Sirius		Alpha CMa A	       -1.45		+1.4		2.7
2	Canopus		Alpha Car	       -0.73		-4.7		60
3	Rigil Kentaurus	Alpha Cen A	       -0.1		+4.3		1.3
4	Arcturus	Alpha Boo 	       -0.06		-0.2		11
5	Vega		Alpha Lyr		0.04		+0.5		8.1
6	Capella		Alpha Aur		0.08		-0.6		14
7	Rigel		Beta Ori A		0.11v		-7.0		250
8	Procyon		Alpha CMi A		0.35		+2.7		3.5
9	Achernar	Alpha Eri		0.48		-2.2		39
10	Hadar		Beta Cen AB		0.60		-3.5		160
11	Altair		Alpha Aql		0.77		+2.3		5
12	Betelgeuse	Alpha Ori		0.80v		-6.0		200
13      Aldebaran       Alpha Tau		0.86            -0.2            16 
14	Acrux		Alpha Cru A		0.90		-3.5		80
15	Spica		Alpha Vir		0.96v		-3.4		80
16	Antares		Alpha Sco A		1.00v		-4.7		130
17	Pollux		Beta Gem		1.15		+1.0		11
18	Fomalhaut	Alpha PsA A		1.16		+1.9		7
19	Deneb		Alpha Cyg		1.25		-7.3		500
20	Mimosa		Beta Cru		1.28		-4.6		150
21	Adhara		Epsilon CMa A		1.50		-5.0		200
22	Castor		Alpha Gem		1.58		+0.8		14
23	Shaula		Lambda Sco		1.62v		-3.4		100
24	Bellatrix	Gamma Ori		1.63		-3.3		93
25	GaCrux		Gamma Cru		1.64		-2.5		70
26	Elnath		Beta Tau		1.65		-2.0		55
27	Regulus		Alpha Leo A		1.99		-0.4		30

Magnitudes

The brightest magnitudes are the largest negative numbers. Originally the plan was to call the brightest visible stars "stars of the first magnitude" or magnitude = 1 and on down to the faintest visible "stars of the sixth magnitude" or magnitude = 6. As measurements improved, it was found that some 1's were brighter than the others, hence numbers smaller than 1, eventually running into negative numbers. The scale is logarithmic, and each increase in 5 magnitudes corresponds to a decrease in brightness by a factor 100. The absolute magnitude is the magnitude the stars would have if viewed from a distance of 10 parsecs or some 32.6 light years. Obviously, Deneb is intrinsically very bright to make this list from its greater distance. Rigel, of nearly the same absolute magnitude, but closer, stands even higher in the list. Note that most of these distances are really nearby, on a cosmic scale, and that they are generally uncertain by at least 20%. All stars are variable to some extent; those which are visibly variable are marked with a "v". You may find a slightly different ordering of magnitudes as measurements are refined.

What are apparant and absolute magnitudes? Apparant is how bright the appear to us in the sky. The scale is somewhat arbitrary, as explained above, but a magnitude difference of 5 has been set to exactly a factor of 100 in intensity. Absolute magnitudes are how bright a star would appear from some standard distance, arbitrarily set as 10 parsecs or about 32.6 lightyears. Stars can be as bright as absolute magnitude -8 and as faint as absolute magnitude +16 or fainter. There are thus (a very few) stars more than 100 times brighter than Sirius, while hardly any are known fainter than Wolf 356.

To see the same list, but with links to pages on the constellations and each star, see Chris Dolan's Stellar Brightness page (nice work, Chris!).

This page, http://casswww.ucsd.edu/public/bright.html, last updated February 8, 1996
Send comments and questions via mailto: Bill Baity, CASS, UCSD 0424, 9500 Gilman Drive, LaJolla CA 92093-0424, tel (619) 534-3209, wbaity@ucsd.edu