Spica

Spica (α Vir / α Virginis / Alpha Virginis) is the brightest star in the constellation Virgo, and one of the brightest stars in the nighttime sky.

In Chinese astronomy, the star is known as Jiao Xiu 1 (角宿一) in Jiao Xiu, one of the Chinese constellations. In Hindu astronomy, Spica corresponds to the Nakshatra Chitra.

Spica is believed to be the star that provided Hipparchus with the data which enabled him to discover precession of the equinoxes. A temple to Menat (an early Hathor) at Thebes was oriented with reference to Spica when it was constructed in 3200 BC and, over time, precession resulted in a slow but noticeable change in the location of Spica relative to the temple. Nicolaus Copernicus made many observations of Spica with his home-made triquetrum for his researches on precession.

The name Spica derives from Latin spīca virginis "Virgo's ear of grain" (usually wheat).

Spica is the brightest of the rotating ellipsoidal variables. Its apparent magnitude varies between +0.92 and +1.04, with a period of 4.0142 days. This slight dip in magnitude is barely noticeable visually. It is also a variable of the Beta Cephei type.

Located close to the ecliptic, Spica can be eclipsed by the Moon and (rarely) by the planets. The last planetary eclipse of Spica occurred when Venus passed in front of the star (as seen from Earth) on November 10, 1783. The next eclipse will occur September 2, 2197, when Venus again passes in front of Spica.

An easy way to find Spica is to follow the arc of the handle of the Big Dipper to Arcturus, and then continue on the same distance to Spica ("follow the arc to Arcturus and speed on to Spica").

In medieval astrology, it was a Behenian fixed star, associated with the emerald and sage. In his De Occulta Philosophia, Cornelius Agrippa attributes its kabbalistic symbol Image:Agrippa1531 Spica.png to Hermes Trismegistus.

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