Spica is the brightest star in Virgo, a close pair of hot blue-white stars that orbit so tightly that each is pulled into an egg shape by the other.
At a glance
| type | blue-white star (class B) |
|---|---|
| distance from the Sun | 250 light-years (76.6 pc) |
| its light left it | 250 years ago |
| luminosity | 20,500 × the Sun |
| radius | 7.47 × the Sun |
| surface temperature | 25,300 K |
| constellation | Virgo (Maiden) |
Read off the piece’s own catalogue, the same values it draws with.
About Spica
What looks like one star is two massive, hot stars circling each other in a matter of days. They are so close that their gravity distorts both into elongated shapes, and as the pair turns we see more or less of their surfaces, so Spica’s light varies slightly in a regular rhythm.
Spica lies near the ecliptic, and the Moon regularly passes in front of it. The ancient astronomer Hipparchus compared his measurements of Spica’s position with older records and found that the stars had shifted, which led him to discover the slow wobble of Earth’s axis now called precession.
What you see in the piece
With HUMAN EYE on it is a bright blue-white point low in Virgo, standing alone in a part of the sky with few bright stars. Close up the light is hot and blue-white.
Questions
Is Spica a binary star?
Yes. Spica is two hot stars in a very tight orbit, distorted by each other’s gravity, which makes its brightness change slightly.