The Milky Way is back

During the hot, steamy nights of July, the Milky Way is a recurrent sight stretching from horizon to horizon. Now’s the best time to view it with the naked eye, and to discover a host of celestial gems within it using a telescope or binoculars. As well, one should not neglect Venus and Saturn, which continue to dominate the evening sky… 

The Milky way is our galaxy — a disk-shaped island of stars that measures about 120 000 light years across with an average thickness of 1000 light years. To visualize it, our galaxy has the same proportions as a thin crust pizza… Our Sun, is an average star among 200 billion others, that is situated in the middle of the disk’s thickness about 26 000 light years from the centre. Seen from our perspective, inside the Milky Way, our galaxy looks like a narrow luminous band that arches overhead. This “milky trail” (as it was known to the ancient Greeks) owes its glow to the cumulative light of hundreds of millions of stars spread throughout the Galaxy’s disk.

However, the stars are not distributed evenly: Some parts of the disk are thicker and brighter than others. Such is the case for the region delimited by Sagittarius and Scorpius, above the southern horizon. The centre of our galaxy lies beyond the stars of these constellations and is demarcated by a prominent galactic bulge, which explains the disk’s increased thickness. At its heart lies Sagittarius A* (pronounced A-star), our  galaxy’s supermassive black hole. This cosmic colossus has a mass of about four million “Suns” contained in a volume smaller than our solar system… Lucky for us, we’re at a safe distance!

Other striking features that await observers who scan the Milky Way between Sagittarius and Cygnus (at the heart of the summer triangle), are the dark zones that seem devoid of stars: The Cygnus rift, in particular, seems to split the Milky Way in two, along its length. These are not “holes” in the Galaxy, but rather foreground clouds of dust and gas that block the light of the stars that lie behind them. We see these dust-lanes silhouetted against the Milky Way’s luminous disk.

Viewed with binoculars, the Milky Way has a “granular” texture, which indicates that it consists of individual stars. And scanning along the Milky Way, between Sagittarius and Cygnus, one can find many nebulae and star clusters, both open and globular, which makes this one of the richest fields for deep-sky objects. Telescopes offer an even more rewarding experience, revealing many unexpected details… An absolute must for your “bucket list.”

And speaking of telescopes, you’ll need one (a small one will do) to see Saturn’s rings. In July, the planet is located in Virgo and is visible in the south after twilight; it sets in the west after midnight. On July 16, the first quarter Moon will pass below Saturn.

The only other evening planet, visible in July, is so bright that it doesn’t require a telescope or the Moon to see it. Of course, we’re talking about Venus, which is visible in the west after sunset. On July 3, Venus will pass just above the Beehive star cluster, also known as M44 (its number in the Messier catalogue). However, observing Venus will still present a challenge, requiring good weather conditions and an unobstructed west-northwest horizon. Binoculars will prove indispensable. During the course of the month, Venus will slowly approach the horizon, and the bright star Regulus, in Leo: the two will be separated by about one degree on the evening of July 21.

Clear skies!