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Algol: Fixed-Star Reference

Beta Persei in Perseus. A dated coordinate note and a careful way to compare the star with a birth chart.

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Algol belongs to Perseus rather than a zodiac constellation. Its fame in star lore often draws readers directly to an interpretation, but the first technical question is how a source places it on the zodiac at all. The answer is a projection from equatorial coordinates onto the ecliptic.

IAU nameAlgol
DesignationBeta Persei · HR 936
ConstellationPerseus
Visual magnitude in IAU table2.09
J2000 right ascension47.042215°
J2000 declination40.955648°
Tropical longitude on 1 Jan 202626.53° Taurus
Ecliptic latitude on 1 Jan 202622.43°

Reading the coordinates

At the stated 2026 reference instant, the projected tropical position is 26.53° Taurus, with ecliptic latitude 22.43°. Its latitude is substantial. A planet at the same ecliptic longitude may still be separated by many degrees in the sky. The locator reports the full angle for that reason.

Right ascension and declination locate Algol on an equatorial sky map; the tropical position rotates and projects that J2000 direction into a dated ecliptic frame. Precession changes the printed zodiac longitude over centuries. It does not move the star from Perseus to a different astronomical constellation. This is why an undated “fixed degree” should be checked against its source.

A useful research question

How far north of the ecliptic is the star at the date being considered? A clear answer identifies the named star, the date, and the method of comparison. Ptolemy’s surviving astrological discussion groups stars by constellation figure and assigns symbolic qualities; it is a historical text, not a measured guide to personal outcomes.

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Position calculation

The IAU table identifies the named star and gives its right ascension and declination at J2000. Astronomy Engine rotates that direction to the true ecliptic and equinox of a chosen date. The displayed tropical longitude is the angle around the ecliptic; latitude records how far above or below that plane the star lies. The reference date on this page is 1 January 2026 at 12:00 UTC.

The calculation does not propagate individual stellar proper motion, parallax, or perspective effects. It is intended for modern reference dates, not ancient reconstructions. A planet sharing a projected longitude with a star can still be far away on the sky. The chart locator shows that full angular separation and limits automatic matches to stars within 40° of the ecliptic.