BellaOnline Forums Education Astronomy Scorpius the Scorpion

Anyone wary of spiders may want to avoid the spider's cousin Scorpius. Most constellations don't look like their namesakes. But Scorpius is easily imagined as a giant scorpion with a blood red heart gleaming in the southern sky. It's been an astronomical scorpion for over 3000 years.

Scorpius the Scorpion

One of the most exotic binary systems we know of is GRO J1655-40. It's some 11,000 light years away, and is made up of a sunlike star and a black hole. The black hole's strong gravity pulls matter away from the other star. But matter doesn't just topple into the black hole. It's pulled into what's called an accretion disk which orbits the black hole at high velocity. Here is an artist's impression of the system. At seven solar masses, the black hole would have formed when a massive star used up its fuel, exploded as a supernova and the remnant collapsed into a black hole.

The hunter Orion and his nemesis the scorpion aren't seen in the sky at the same time. Orion is seen in northern hemisphere winter and Scorpius in the summer.

Here's a size comparison between the Sun, Arcturus and Antares. The Sun contains some 99.9% of the mass of the whole Solar System, so we think of it as pretty big. But it's just a dot compared to Arcturus, the red giant star in Boötes the Herdsman. And even that's small compared to Scorpius's Antares.