Scorpius rising

A few weeks ago, I was sitting beside Hoopers Inlet, enjoying the tail end of what had been a rather beautiful auroral display, writes Ian Griffin.

As the glow of the southern lights faded, my eyes were drawn to a marvellous sight in the eastern sky. The constellation Scorpius was rising. Moreover, as the night was calm, a mirror image of the distinctive ‘‘sting’’ could be seen reflecting from the inlet’s mirror-like surface.

For several minutes, until a light breeze disturbed the starry scene, I was transfixed by the colourful celestial reflections.

Studying those colours helps us to understand the surface temperatures of the stars. Red stars such as Antares (the brightest star in Scorpius) are much cooler than the sun, while stars such as the nearby and distinctly blue Tau are hotter.

Antares is a red supergiant star about 550 light-years from us. It is so big that, placed in our solar system, it would gobble up all of the planets out to Mars!

Scorpius is one of the most distinctive constellations in the sky.

According to legend, it is the killer of Orion the Hunter. Orion was so terrified of the murderous arachnid that since Zeus raised him and the scorpion to the heavens, he flees from it. To this day, as Scorpius rises in the east, Orion is setting in the west.

With the new moon on April 12, this week is the perfect time to observe Scorpius rising for yourself. The constellation is low in the sky at sunset, but by 9pm, Antares is more than 10 degrees above the horizon. While the best views will be obtained from rural locations, the stars of Scorpius are so bright that it is easy to see them from the centre of Dunedin.

Our local star, the sun, is situated on the outskirts of the Milky Way galaxy. When we look towards Scorpius, we look towards the centre of our home galaxy, a star-rich region teeming with gas and dust. If you have a pair of binoculars, it is well worth using them to scan across this beautiful part of the sky.