For many of us, August is synonymous with shooting stars. Despite the name, shooting stars are not actually stars, just tiny flecks of dust that burn up upon entry into Earth’s atmosphere. Meteor showers are caused by clouds of dust particles that lie in Earth’s path around the Sun. Since our planet follows the same path year after year, the showers usually occur at the same period as well. This month’s main attraction will be the Perseids.
The Perseid meteor shower—resulting from Earth crossing the stream of dust left behind by comet Swift-Tuttle—is one of the year’s most spectacular and certainly the most popular in the Northern Hemisphere. When viewing conditions are ideal (no clouds, haze, moon, light pollution, etc.), one can expect up to 100 meteors per hour, all appearing to originate from the same region of the sky: the constellation Perseus.
What can we expect in 2021? Peak activity is expected around 3 p.m. (ET) on August 12—that’s broad daylight in our time zone. So, as you can imagine, it will not be possible to observe the meteor shower from our location at the exact peak time. However, the best night to see the Perseids, here in North America, will be August 12-13. And since the Moon will be a waxing crescent (the new Moon occurs on August 8), it will already have set before the end of twilight and will not interfere with our viewing. The Perseid meteor shower is active from dusk to dawn, but the number of visible shooting stars increases significantly as the hours progress towards dawn, when the radiant—the area of sky where the meteors seem to originate—is at its highest point. If you have cloudless skies, an open view of the sky, and are far enough away from light pollution, you should be able to spot a good 50 or so meteors per hour. If you’re unlucky and the weather is bad, the night of August 11-12 will also provide excellent displays. In fact, the first Perseids can be spotted as early as mid-July; their numbers increase until the night of peak activity and then decrease until the third week of August. Get your wish list ready!
The giants and their escorts
August is not only about the Perseids; this year, it will also be the perfect time to check out the two Solar System giants, Jupiter and Saturn, since they will both reach opposition (the most favourable position for observation) during the month. In this configuration, our Earth sits between the Sun and the planet in question, and the distance separating us from that planet is, in theory, the smallest it will ever get. But since planetary orbits are not perfectly concentric circles, opposition and closest distance do not usually occur at the same time, but rather a few days apart.
Saturn—by far the most beautiful jewel in the evening sky visible by telescope—will be in opposition on August 2 in the early morning hours. The lord of the rings is currently in retrograde motion in the constellation Capricornus, 18 degrees below the celestial equator, at about 74 light-minutes (1,336,656,975 km) from Earth. Saturn’s famous rings make it a target of choice for observers with telescopes; the rings will be tilted 18 degrees towards the Earth, providing a good view of its details. Choose a location that offers an unobstructed view of the southern horizon, ideally in the middle of the night when Saturn is at its highest.
Jupiter—the largest planet in the solar system and fourth-brightest object in the sky—will be in opposition on the night of August 19-20. Jupiter will be in retrograde motion, just like its sister gas giant, but in the constellation Aquarius at the start of the month, before crossing the border of Capricornus on August 18. The planet can currently be found 14 degrees south of the celestial equator, at a distance of 33 light-minutes (599,887,459 km) from Earth. Unlike the rings around Saturn, Jupiter’s rings are nearly imperceptible and not visible from Earth. However, a small telescope will reveal a pattern of light and dark cloud bands in the planet’s atmosphere along with its four largest natural satellites: the Galilean moons Io, Europa, Ganymede and Callisto. In fact, these moons will be at their brightest at the time of Jupiter’s opposition. And, by strange coincidence, they will also all be close to their greatest elongation from the planet, making the night of August 19-20 a great time to explore the gas giant.
Jupiter and Saturn will be visible most of the night all month long, so go ahead and treat yourself to some great views!
Planets at twilight
Brilliant Venus boldly stands out as soon as the sky darkens after sunset, less than 10 degrees above the western horizon; the gibbous Moon will be its neighbour on the evenings of August 10 and 11. Lower and to the right of Venus, Mercury and Mars also make an appearance at twilight but are much harder to spot than the Evening Star, notably because they are much dimmer as well as a lot closer to the horizon than Venus. By mid-August, the Sun catches up with Mars, which disappears in our star’s glare; the Red Planet eventually passes behind the Sun on October 8.