Scorpius

Scorpius is one of the easier recognisable constellations, not to confuse with Scorpio, the name for the astrological sign of the Zodiac. At the moment Scorpius is right above us here in the southern hemisphere.

In the Greek mythology the scorpion was send by the gods to kill Orion, the great hunter, after he had boasted to kill all animals on Earth. They fought for a whole day and finally were exhausted. When Orion fell asleep the scorpion stung him, Orion woke up and killed the scorpion but then died from the poison. The gods placed them amongst the stars in the sky but far apart so they could not fight anymore.

The tail of Scorpius lies in the Milky Way, the city of stars in which we live. When we look at the tail of Scorpius
and the next constellation, Sagittarius, we look towards the centre of our galaxy. The central bulge is obscured by opaque foreground clouds however and can’t be seen. Still most of the light we see in this area comes from about 25,000 light years away.

In the body of Scorpius we see the brightest star of the constellation, Antares. Its name is Greek for “rivalling Mars” (anti-Ares, where Ares was the Greek name for the God of war, which was called Mars by the Romans) since it is very bright and reddish in colour, just like the planet. However Mars is a tiny planet while Antares is a red super-giant, probably about 200,000 times greater in diameter. The reason they look similar is because of the huge difference in distance. Where Mars is only 5 to 20 light minutes away, Antares lies at a distance of about 600 light years. It is the 15^th brightest star in the sky and about 10,000 times more luminous than our Sun. Estimates of its diameter vary from 280 to 700 times that of the Sun, but it is only about 15 times more massive than the Sun and has therefore a very low density. The reddish colour is the result of a relatively low surface temperature and its brightness fluctuates from 0.9 to 1.2 every four to five years.

In Scorpius you can also find some nice open and globular clusters that can be viewed with binoculars or small telescopes. The nicest ones to observe are M6 and M7, close to the tail of Scorpius. These are two prominent open star clusters that can be seen with the naked eye as hazy patches. With binoculars you can see tens of individual stars in each. M7 is about 8,000 light years away and M6 twice as far. M6 is also called the butterfly cluster because of its shape when viewed with binoculars. There are some other clusters in this constellation, like M4 close to Antares, but they are fainter and less nice to view with amateur telescopes.
Close to Scorpius pinchers lays Scorpius X-1, this is the strongest X-ray source in the sky. It consist of a 13^th magnitude blue star, orbited by a neutron star.

All in all Scorpius is an interesting constellation to view.

Happy stargazing from Balule,
Miriam