Spread out the blanket and get comfortable! Planets, the Moon, the Milky Way and exotic objects: There’s something for everyone in this year’s July sky.
First up: Mercury
You still have a day or two in early July to catch the five-planet parade (which was visible to the naked eye in the second half of June) before Mercury vanishes in the Sun’s glare. The tiny planet rises only 30 minutes before the Sun, and spotting it will be a major challenge even if you have a perfectly clear view of the east-northeastern horizon. The other planets will be your best guides to help you locate the elusive Mercury.
The planets all orbit the Sun in roughly the same plane, and that plane passes through the constellations of the zodiac. Therefore, from our Earthly viewpoint during the wee hours in early July, four clearly visible planets—four of the brightest points in the sky—form a long line from south to east towards Mercury.
A skewer of planets
From their respective risings to that of the Sun’s, our main planetary quartet continues to light up the July nights.
Saturn is the first to emerge above the east-southeastern horizon, around 11 p.m. at the beginning of the month, then increasingly earlier until 9 p.m. in early August. The beautiful ringed planet is almost stationary and outshines all the stars of the constellation Capricornus, near Aquarius in July. The Moon inches toward Saturn on the evenings of July 14 and 15 (about 6 degrees on the 15th), serving as a guidepost to finding the distant planet.
Jupiter rises about 90 minutes after its neighbour. Currently in the constellation Cetus, just below Pisces, the giant planet rises above the eastern horizon around 12:30 a.m. in early July and 10:30 p.m. by month’s end. Jupiter is very easy to spot: Apart from the Moon, it is by far the most luminous object in the second half of the night, until Venus rises in the east-northeast at daybreak. Stay tuned for a beautiful Moon-Jupiter conjunction during the night of July 18 to 19, when our satellite lies 3 degrees below the rising planet.
Mars is the next to emerge. With the Earth slowly closing in, the Red Planet increases in magnitude and appears to be moving rapidly against the background constellations of the zodiac. On July 1, it can be found near the junction of the two fish of the constellation Pisces and rises at about 1:30 a.m. It sits in the middle of Aries by month’s end, rising around 12:15 a.m. Mars also gets a visit from the Moon, which passes less than 4 degrees from the planet during the night of July 20 to 21.
But the showstopper remains the very brilliant Venus, despite its gradual dimming. It rises in the east-northeast between 3:30 a.m. (July 1) and 4 a.m. (July 30); an hour later, just as civil dawn begins, Venus reaches an altitude of 11 degrees before getting swallowed up in the glare of the rising Sun. Try to catch a glimpse of Venus on the morning of July 26, when it appears to hang less than 4 degrees below a very thin lunar crescent.
Extra-large full Moon
The biggest full Moon of the year occurs on July 13, only nine hours after our satellite will be at its closest point to Earth (perigee, at 357,264 km) in its elliptical orbit. This is known as a perigee full Moon, or what we commonly call a “supermoon.” This proximity translates into an observable diameter 10% larger than the farthest full Moon of 2022, which was in January. However, it will be impossible to tell the difference with the naked eye due to the lack of reference points. The effect will nonetheless be notable due to the high tidal ranges at that moment and over the following days.
It is always a good time to turn our gaze to our celestial sidekick. In addition to this full Moon and the planetary meetups mentioned earlier, here are a few of the most noteworthy encounters. As night falls on July 2, the four-day crescent Moon lies near the star Regulus in Leo; note the earthshine on the part of the Moon not directly illuminated by the Sun. On the evening of July 10, the star Antares—the red “heart” of Scorpius—and the gibbous Moon come to within 2 degrees of each other. On the morning of July 23, after rising at about 1 a.m., the last crescent Moon hangs in Taurus, between the Pleiades star cluster and the orange star Aldebaran.
But of all these encounters with the Moon this month, the closest and most mysterious is the one on July 11. Could it also be the most dangerous?
Doughnut and black hole as a final treat
On May 12, 2022, an international team of astronomers unveiled the first image of a cosmic body known as Sagittarius A*, a supermassive black hole at the centre of our own Milky Way galaxy. The radio image reveals the dark silhouette of this gravitational abyss that heats up the matter swirling around it, causing it to glow.
This black hole is four million times more massive than our Sun and is located, from our vantage point on Earth, in the constellation Sagittarius. July evenings are undoubtedly the best time to observe this region of the sky at the core of the Milky Way.
Here’s where to look if you want to gaze in the direction of this black hole. Face south-southeast at astronomical twilight to locate the main stars that form a teapot in the constellation Sagittarius. Draw an imaginary line from the base of the teapot’s handle (the star Ascella) to the beginning of its spout (the star Kaus Media). Then double the length of this line to find the location of Sagittarius A* and the core of the Milky Way.
In the evening of July 11, the waxing gibbous Moon will pass a mere 2 degrees above this galactic glutton; use it to help you look in the right direction. There’s no need to worry about our natural satellite, the black hole is actually 26,000 light-years away from us—660 billion times further than the Moon! And don’t be surprised if you can’t see the same image as the one revealed in May: From our Earthly viewpoint, this doughnut of matter surrounding the black hole appears to be the same size in the sky as a real doughnut... observed on the surface of the Moon!
On that note, bon appétit!
Clear skies!
