In the northern hemisphere, June is the time of year with the longest days, but also the shortest nights. At our latitudes, we must wait till 11 p.m. for the sky to be totally dark. Stay up late enough and you’ll be treated to one of the most breathtaking objects seen through a telescope in the June sky: the Hercules Cluster.
The Hercules Cluster is known as a globular cluster, a sphere-shaped concentration of stars. Edmund Halley, the scientist who also discovered the periodicity of the famous comet that now bears his name, observed this cluster for the first time in 1714. On June 1, 1764, French astronomer Charles Messier made the cluster the 13th entry in his well-known catalogue of deep-sky objects. Ever since then, astronomers have referred to the cluster as “M13.”
As its more common name suggests, the cluster lies in the constellation Hercules, which is found very high in the June sky. In the countryside on a moonless night, you can even make out M13 with the naked eye. It appears as a dim spot of hazy light that’s slightly broader than a star. Though it’s not dazzling to the naked eye, you should still feel proud if you manage to ferret it out. The Hercules Cluster reveals its full splendour when seen through a telescope of 15 cm or larger. The object is remarkably intricate as it’s made up of thousands of stars. You’ll be instantly struck by how complex our Universe is. The larger your telescope, the more amazing the experience.
Consisting of hundreds of thousands of stars spread across only 145 light-years, the cluster is like a mini-galaxy floating on the outskirts of the Milky Way. At the cluster’s core, the stars are so close together that astronomers believe that planets there would have trouble remaining in orbit around a single star. Instead, they would be pulled by gravity along a winding path through the cluster. The stars in globular clusters are among the oldest in the Universe (some are over 12 billion years old). Any exoplanets found within these clusters would also be incredibly old. As you admire M13 through a telescope, keep in mind that it may harbour planets that are almost three times older than Earth.
If you want to observe the Hercules Cluster but don’t have a telescope or can’t track M13 down, why not contact an astronomy club in your area for assistance.
The Moon and planets in June
As for the planets, bright, lovely Venus is easy to make out in the west after sunset. Always spectacular with binoculars or a small telescope, Jupiter appears in the south at nightfall. Mars shows up later in the southeast around midnight, and you may often have to wait even later to see the red planet rise above the trees and rooftops.
Saturn, which lingers all night long in June, may well steal the show this month. The ringed planet is in opposition on the 27th, meaning it’s diametrically opposite the Sun in the sky. Hence, when the Sun sets (in the west), Saturn rises (in the east) and vice versa. On the night of June 27 to 28, the Full Moon lies only one degree above Saturn. Strangely enough, the brilliant Moon makes it quite easy to spot Saturn because the planet is one of the only objects near the Moon to shine through the surrounding brightness.
Finally, since it’s June, we mustn’t overlook the solstice, which occurs this year on the 21st at 6:07 a.m. in our time zone. The June solstice is the time of year when the Sun reaches its highest point above the northern hemisphere; at that moment, it shines vertically down on the Tropic of Cancer. From an astronomical point of view, the solstice kicks off the summer season in the northern hemisphere and the winter season in the southern hemisphere.