Star profile
Algol
Beta Persei · Perseus
Variable starWhat is Algol
Algol is Perseus's fabled «demon's head», a name drawn from the Arabic «raʾs al-ġūl». Every 2.87 days its brightness drops in a way the naked eye can register, and for centuries it was thought a cursed star; today we know it as an eclipsing system, where an unseen companion passes periodically in front of the brighter star. Its light travels barely 90 years to reach us — still carrying an echo of those ancient fears.
Where it is and when to see it
Algol lies in the northern celestial hemisphere. It is visible to the naked eye under a dark sky. Its best month of the year is November, when it culminates around midnight.
- From London it never sets and culminates about 79° up.
- From New York it culminates about 90° above the horizon.
- From Sydney it culminates about 15° above the horizon.
It can be seen from anywhere north of 49° S.
It ranks no. 2 in brightness among the 99 stars of Perseus in our catalogue. To find it, start from Mirfak, the brightest: it lies about 9° away (a fist at arm's length covers about 10°).
The light you see today left it about 90 years ago.
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A public signature from a real person. The chosen name is a symbolic denomination within Stelvia, with no official standing or IAU recognition: the sky is not for sale and belongs to no one.
Astronomical data for Algol
- Constellation
- Perseus
- Apparent magnitude
- 2.09
- Distance
- 89.9 light years
- Coordinates (J2000)
- RA 47.042° · Dec 40.956°
- Catalogue
- HIP 14576 · HD 19356
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Other stars in Perseus
Perseus has 99 stars in Stelvia's catalogue. Here are a few of them.
- MirfakAlpha Persei1.79
- Zeta Persei2.84
- Epsilon Persei2.90
- Gamma Persei2.91
- Delta Persei3.01
- Rho Persei3.32
- MiramEta Persei3.77
- Nu Persei3.77