Cast your eye to the southern sky

The sagittarius region boasts a rich collection of nebulae and star clusters. - john mcphee

IT'S LUCKY FOR modern stargazers that comet hunter Charles Messier was an organized sort of chap.

When the 18th century French astronomer came across something that later could be mistaken for a comet, down it went into his notebook. His list of things to ignore evolved into a valuable record of the sky's most impressive sights, from M1 to M110.

The southern horizon in summer boasts a treasure trove of these objects, particularly in the constellations Scorpius and Sagittarius. This area is packed with star clusters and clouds of glowing gas and dust called nebulae.

This month marks prime-time viewing for Scorpius although it crawls pretty low along the horizon in the northern hemisphere. Scorpius is named for the venomous desert arachnid that, in Roman mythology, killed Orion, the glittering hunter whose constellation haunts the winter skies far away from his mortal enemy.

Unlike a lot of constellations, Scorpius doesn't require much of an imaginative leap to see the creature behind its' name. The scorpion hangs just above the southern horizon - a fishhook or the letter J also comes to mind.

At the heart of Scorpius beats Antares, the star whose red hue inspired the Romans to name it the "rival of Mars." About 500 of our suns could fit into Antares, a red giant star about 500 light-years away.

But time is running out for this huge ball of gas. Its density is less than one-millionth that of our Sun and when it finally runs out of fuel, “Antares will collapse and explode in a supernova - at which time its brightness will rival that of the rest of our galaxy put together,” according to NASA scientists.

If you train a pair of binoculars on Antares, you may notice a hazy patch in the same field of view to the right. That's M4, a group of stars called a globular cluster. M4 may look like Antares' neighbour but this incredibly dense group containing hundreds of thousands of stars lies 7,500 light-years from Earth.

Saturn, Mars and the star Antares line up in the constellation Scorpius on Aug. 24, 2016. That line through Antares is a satellite. - john mcohee

As with all globulars, it takes a larger telescope to make out individual stars in M4. In my 90-millimetre scope, the foggy patch takes on a sort of pebbly appearance, particularly on a night of good "seeing" - that is, when the atmosphere is steady and there's little haze in the air.

A more satisfying sight in binoculars and small scopes are looser collections of stars called open clusters. Scorpius boasts a couple of beauties, M7 and M6. They lie just above the tail of the scorpion. On a moonless night of great seeing, M7 shines like a scattering of jewels in my 10x50 binoculars. I can also make out the nebula in M6.

You can often get a better view of fainter objects like nebulae if you don't look right at them. Avert your eyes slightly to the side and a more distinct image pops into view. This technique takes advantage of more light-sensitive areas on the sides of the retina.

Whatever part of the eye you use, it’s the best time of year to soak up the celestial riches at the heart of our home galaxy.