Spica
HIP 65474; Alpha Virginis; 67 Virginis
About Spica
Description
Spica is a blue giant of spectral type B1III-IV at magnitude 0.98, the brightest star in Virgo and the 16th brightest in the sky. Located about 250 light-years from Earth, it is actually a close binary system — two hot stars orbiting every 4 days, so close they are distorted into egg shapes by tidal forces. The combined luminosity is about 12,100 times solar.
Observing Tips
Follow the arc of the Big Dipper's handle past Arcturus to 'speed on to Spica' — extending the arc about the same distance. Spica is a brilliant blue-white star low in the spring sky, marking the sheaf of wheat held by the Virgin. It is a useful guide to the Virgo Cluster of galaxies, which lies about 10° to the northwest. Best observed April through July.
History
The name Spica means 'ear of grain' in Latin, referring to the sheaf of wheat in the constellation figure. Hipparchus used observations of Spica around 130 BC to discover the precession of the equinoxes — one of the most important discoveries in ancient astronomy. Copernicus also used Spica to calibrate his observations.
Fun Facts
Spica is a rotating ellipsoidal variable — the two tidally distorted stars present different cross-sections as they orbit, causing tiny brightness changes. Both stars are so hot and massive that they will end their lives as supernovae, possibly leaving behind a double neutron star or even a black hole binary.
Observe
1Physical Properties
Position & Identifiers
2How easy to split?
| Telescope | Bortle 3 | Bortle 4 | Bortle 5 |
|---|---|---|---|
| 80 mm refractor 80mm refr. | V. hard+ | V. hard+ | V. hard |
| 150 mm Newton 150mm Newt. | Medium | Hard+ | Hard |
| Celestron C8 (203 mm SCT) C8 203mm | Medium+ | Medium | Hard+ |
Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs
3Visibility
Set a location in User Settings to see visibility data.
4Light Curve
5Multiple Star System
Eyepiece View
A: 1.0 · B: 12.0 · Sep: 151.9″ · PA: 33° · N up, E left
Resolved · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 2.3″
Explore
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Size Comparison
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Compare Stars
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Stellar Lifecycle
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Spectral Classification
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Hertzsprung-Russell Diagram
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Blackbody Spectrum
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Stellar Absorption Spectrum
Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.
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Stellar Fusion
Discover
15Stellar Notes
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Light Travel Time Machine
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Relativistic Travel
Survey Image
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Nearby in the Sky
Other targets within a few degrees — pan your scope a little and keep exploring.
