Although the days are truly longer during the summer solstice, something about the air in July—be it the whiff of vacation, the oppressive heat or the lighter traffic—seems to stretch time out.
Even planet Earth shifts into “low” gear. In early July (on the 5th to be exact), Earth will be at aphelion, its farthest point from the Sun during its elliptical orbit—152 million kilometres from our star. And yes, Earth truly is farthest from the Sun during summer, for the Northern Hemisphere that is (remember that it’s winter in the Southern Hemisphere). Despite the Earth-Sun distance being 3.5% larger than on January 2, that extra distance doesn’t come close to counteracting the effect of Earth’s tilted axis, which is what really causes the changing seasons. Rather, aphelion is the moment when our planet is moving at its slowest (105,000 km/h) around the Sun, 4,000 km/h slower than at the beginning of the year. This slowdown is akin to taking the scenic route to better enjoy the view—it allows us some extra time to gaze at the beautiful summer constellations.
The best time to enjoy the cozy, star-filled evenings will be in the first half of the month, when the Moon’s phase will be favourable during the days surrounding the July 10 new Moon. Far from the light pollution of large urban areas, and with our natural satellite out of the way, the night will reveal plenty of low-magnitude stars and, more importantly, the core of the Milky Way rising up towards the Summer Triangle, due south in the constellation Sagittarius. Scan this region of the sky with binoculars and you’ll see multiple star clusters and stellar nurseries, such as the Lagoon Nebula (Messier 8) coupled with a cluster of young stars. To catch a glimpse, look for the teapot in the constellation Sagittarius; M8 will be lying just above the spout, slightly higher than the lid, about 5,000 light-years away. On the evening of July 21, the waxing gibbous Moon, located a mere 1.3 light-seconds from Earth, will appear to shine less than 3 degrees to the lower left of M8; the two celestial bodies can be seen together through binoculars, theoretically making it easier to locate the distant nebula but also more difficult to view it because of the Moon’s dazzling light.
As Venus continues to pull away from the Sun, its brightness overshadows that of Mars in the twilight glow. This is a particularly striking sight, what with both planets very low on the western horizon, 45 minutes after sunset: Venus pops out more readily than the Red Planet.
From July 1 to 3, Venus brushes by the Beehive cluster (Messier 44), offering a wonderful opportunity to view it through optical instruments. Aim binoculars at the planet and you’ll see the brightest stars in the cluster, not too far off, trying to pierce the glow of twilight. A telescope will reveal Venus as a small, gibbous disc with a diameter of only 11 arc seconds.
Venus also offers us one of the last good opportunities to spot tiny Mars before it slips behind the Sun from our vantage point on Earth. In the first half of July, dazzling Venus approaches from the right of the faint Red Planet, which grows ever dimmer above the western horizon with each passing day. The two planets are in conjunction on the evening of July 13, only ½ a degree from each other. The very thin crescent Moon joins the duo and presents an interesting viewing challenge: On July 11, it hangs 5 degrees to the right of Venus and the following evening, it moves 7 degrees to the upper left of the planet.
Jupiter and Saturn offer better viewing conditions and, as the weeks go by, we don’t have to wait as long to spot them. For example, Saturn rises in the southeast two hours after sunset in early July (around 11 p.m.), but only 30 minutes at the end of the month (around 9 p.m.). Brilliant Jupiter follows suit about an hour later, also above the east-southeastern horizon.
Both giant planets dominate the constellations of Capricornus and Aquarius and their rather faint stars, beneath the trio of bright stars that make up the famous Summer Triangle asterism. One way to locate Saturn in the sky this year is to draw a line from Vega (the highest) to Altair—the two brightest stars of this summer asterism—and to then double that distance toward the horizon and the ringed planet.
You’ll also be treated to a beautiful encounter between our natural satellite, Saturn and Jupiter during the three nights following the full Moon of July 23.
Early risers can enjoy the two giant planets perched above the southern horizon until dawn, at which point Mercury also makes an appearance. Mercury reaches its greatest elongation from the Sun on July 4; it can be found very close to Zeta Tauri, the star that marks the tip of Taurus’s southern horn.
Despite its distance from the Sun, Mercury remains difficult to see because the tiny planet stays low on the horizon at dawn, barely 10 degrees high in the east-northeast. The best time to look for it will be on the morning of July 8: If you can spot the very thin lunar crescent within 45 minutes of sunrise, note that the bright dot of light glowing less than 5 degrees to its right is the tiny rocky planet.