At only 250 light years from earth is Spica, the fifteenth brightest star in the sky and the alpha star of Virgo.
Though Spica glows like a single bright point of light, it’s really a star system, a binary whose primary and secondary components can only be separated by their spectral lines. They’re each main sequence stars, but the primary is a blue-white giant with enough mass that it could one day disappear in a supernova explosion. The secondary is much smaller but is still seven times larger and 1,800 times brighter than the earth’s sun. Each of the stars is rotating at a speed of 200 km/sec and they complete one orbit around each other every four days.
Spica was studied by Hipparchus in the second century BCE when he calculated that the earth is wobbling slightly as it spins on its axis, causing a westward shift in the stars, noticeable over thousands of years.
The Galaxies of Virgo:
The Virgo Cluster
Though clusters of galaxies are almost an unimaginable concept, in space terms they aren’t that unusual. Within the constellation of Virgo are numerous clusters of galaxies that have been glowing, spinning, and expanding for millions of years.
Our Milky Way galaxy, for instance, contains some of the oldest stars in the universe. We’re part of the Local Group of galaxies that itself is located within the Virgo Supercluster.
Abell 1689 is over 2 billion light years away in the constellation Virgo and is one of the largest clusters of galaxies in the known universe