Spica

Spica (α Virginis) is a brilliant first-magnitude star, believed to be the star that provided Hipparchus with the data which enabled him to discover precession of the equinoxes. The temple at Thebes was oriented with reference to Spica in about 3200 B.C. when it was constructed, and over time, precession resulted in a slow but noticeable change in the orientation of Earth relative to Spica using the temple's fixed orientation and construction date to compare against. Nicolaus Copernicus also made a lot of observations of Spica with his home-made triquetrum[?] for his researches on precession.

The name Spica derives from the Latin spica, an ear of grain.

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

Some facts about Spica

• Distance from Earth[?]: 262 light-years
• Spectral type: B1 V
• Radial velocity: 1 km/s
• Proper Motion: 0.053 arcsecs/year
• Apparent Visual Brightness[?] (Sirius A = 1): 0.108
• Apparent Visual Magnitude: 0.98
• Absolute Visual Magnitude: -3.55
• Luminosity: 2.5e4 Solar Luminosities

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Spica is also the first Slovene astronomical magazine, edited by Bojan Kambič and published since 1995 (Slovene Spika (http://slo-astro.lmbitea.si/spika)).