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public LocationGreenwich, UK
Sunrise: 5:08 
Transit: 13:06 
Sunset: 21:03
wb_twilight   (Astronomical Twilight)   What's Visible Now?
All Constellations » Perseus » 

Algol - β Persei (beta Persei)

Above the horizon.  Circumpolar today
Alt: 28.81°   Az: 59.17°   Direction: East-North-East

Algol, also designated as β Persei (beta Persei), is a variable and multiple main-sequence star of spectral class B8 in the constellation of Perseus.

Algol visual magnitude is 2.12, making it the 60th brightest star in the sky. Because of its brightness, Algol is clearly visible to the naked eye when observed from locations with dark skies, and should be also quite easily visible from light polluted areas.

Image of Algol - β Persei (beta Persei) star
DSS2 image of Algol. The red arrow shows the motion of Algol during the next 100000 years (6.67 arcmin in Right Ascension and -1.67 arcmin in declination);

Celestial Coordinates


03h 09m 46s
+41° 02’ 54”
17h 44m 23s
20h 54m 10s


03h 08m 10s
+40° 57’ 20”

Galactic Coordinates


Finder Chart

Finder chart Algol - β Persei (beta Persei) star
Simplified finder chart for Algol - β Persei (beta Persei).

Magnitude, Color, Spectral Class



The red dot in the diagram below shows where Algol is situated in the Hertzsprung–Russell diagram.

HR Diagram
H-R diagram showing the position of Algol. Attribution: Richard Powell / CC BY-SA

Star System Properties

Algol is a visual double star which can be observed only with the help of very large telescopes. The table below shows key information about the Algol double sysyem:

81.9 arcsec

Distance, Radial Speed, Proper Motion

Algol is distant 92.77 light years from the Sun and it is moving far from the Sun at the speed of 4 kilometers per second.

4 km/s
0.004 arcsec/y

Alternative Designations

β Persei
(beta Persei)

Visibility from Your Location

Algol - β Persei (beta Persei) is circumpolar and transits at 07:15 UTC (altitude: 79.6°)