Spica is the brightest star in Virgo and about the 15th-brightest star in the night sky. It is actually two hot blue stars, orbiting each other every four days, about 250 light-years away. It is a spring evening star in the Northern Hemisphere; find it by following the Big Dipper’s handle to Arcturus and then “speeding on” to Spica.
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Spica at a glance
| Other names | Alpha Virginis, Chitra (India) |
|---|---|
| Constellation | Virgo (the Maiden) |
| Brightness | Magnitude about +0.97 |
| Distance | About 250 light-years |
| Type | Close binary: blue giant (B1) + blue main-sequence star (B2) |
| Masses | About 11 and 7 Suns |
| Orbit | 4.01 days |
| Temperature | About 25,000 K (main star) |
| Luminosity | About 20,000 times the Sun (both stars) |
| Best time to see it | Evenings around May (highest at about 9 p.m.) |
| Where on Earth | Visible from everywhere south of about 79°N |
How to find Spica
Use the Big Dipper. Follow the curve of its handle to the bright orange star Arcturus (“arc to Arcturus”), then continue the same curve about the same distance again to reach a bright blue-white star low in the south: Spica (“speed on to Spica”). It is the brightest star in Virgo, which otherwise is a large but faint constellation.
Spica is a spring and early-summer evening star in the Northern Hemisphere (April to June is best) and an autumn evening star in the Southern Hemisphere. In November it is close to the Sun and appears only in the morning twilight. Because it is just south of the celestial equator, it can be seen from almost everywhere on Earth.
Two stars that distort each other
Spica is a spectroscopic binary: two hot blue stars so close together that no telescope can separate them; their presence is revealed by their spectra. The larger star is a blue giant of about 11 solar masses, the smaller about 7. They orbit each other every 4.01 days, and they are so close that their gravity pulls each star into an egg shape. As they rotate, we see slightly more or less of their surface, so Spica’s brightness varies very slightly, an effect called ellipsoidal variation. The main star is massive enough to end its life as a supernova one day.
The star that revealed Earth’s wobble
Around 130 BC the Greek astronomer Hipparchus compared his measurements of Spica’s position with records made about 150 years earlier and found that it had shifted by about 2 degrees. He had discovered the precession of the equinoxes, the slow wobble of Earth’s axis that also explains why Polaris will not always be the North Star.
Spica, the Moon and the planets
Spica lies only about 2 degrees from the ecliptic, so the Moon and planets often pass close to it, and the Moon sometimes hides it in a lunar occultation. In November 2026 brilliant Venus is near Spica in the morning sky as part of the November planet parade.
Names
Spica means “ear of grain” in Latin; the star marks the ear of wheat held by the Maiden. In India it is Chitra (“the bright one”), a nakshatra used as the reference point for the widely used Lahiri (Chitrapaksha) ayanamsa in Indian astronomy.
Spica and the spring sky
Spica forms the Spring Triangle with orange Arcturus and Regulus in Leo, and, together with Arcturus, Denebola and Cor Caroli, a larger shape called the Great Diamond. The region between Spica and Denebola in Leo holds the Virgo Cluster, a group of more than a thousand galaxies about 55 million light-years away, a famous hunting ground for owners of small telescopes on dark spring nights.
Because Spica is a close pair of hot, massive stars, it is also a laboratory for astronomers: the strong tidal forces between the two distort their shapes and slowly change their orbit, helping scientists test models of how massive stars evolve.
Frequently asked questions about Spica
How do I find Spica?
Follow the curve of the Big Dipper’s handle to Arcturus, then continue the curve to the next bright blue-white star: Spica.
Is Spica one star or two?
Two. Spica is a close pair of hot blue stars orbiting each other every four days, too close to separate with a telescope.
How far away is Spica?
About 250 light-years.
When is Spica visible?
On spring and early-summer evenings in the Northern Hemisphere. In November it is near the Sun and only visible low in the dawn sky.
What is Spica called in India?
Chitra, one of the 27 nakshatras.
Sources: Spica overview and references. Star data from standard catalogues; positions and rise/set times are calculated by SpaceTracker.live with the Astronomy Engine library.