Each August brings the return of the Perseid meteor shower, the year’s most famous shower. The Perseid shower is well-known because it’s reliable, and also because it occurs in mid-summer, when the weather is generally better in the northern hemisphere. In a good Perseid shower we get about 80 meteors an hour.
This year, the Perseid shower will peak in the early morning hours of Aug. 12. In other words, stay up late on Aug. 11; viewing should be good from midnight until dawn on Aug. 12. Viewing should also be good in the early hours of Aug. 11 and 13, starting after midnight.
We are fortunate this year in that the moon, a foe of meteor viewing, sets before midnight on all three of the good viewing nights, and will thus be well out of the way by the time the shower peaks after midnight.
The Perseids get their name from the constellation of Perseus the Hero, which rises in the northeast right around midnight in mid-August. The shooting stars appear to come from that part of the sky where Perseus is located. The Perseids are sometimes called "The Tears of St. Lawrence" after St. Lawrence, whose Aug. 10 (A.D. 258) martyrdom on a gridiron is depicted in varying levels of grisliness on many medieval and renaissance works of art.
Meteor showers are caused when the earth wanders into leftover comet debris. As a comet approaches the sun in its orbit, the comet leaves a trail of dust behind it. As the earth orbits the sun, we wander into a given comet’s debris at the same time every year. Thus, shooting-star showers recur at the same time every year.
Every August, we wander into the debris left over by comet Swift Tuttle. The little bits of comet dust hit our atmosphere and burn up from the friction, causing the Perseid meteor shower.
This also explains why meteor viewing is always better after midnight. After midnight, your part of the earth starts facing into the comet debris. More comet dust hits the atmosphere above your head, and you see more shooting stars.
To view a shooting-star shower, you do not need a telescope or binoculars. Find a spot with a good view of full sky. Get away from distracting street or house lights. Make sure you’re comfortable, since you’ll be looking up a lot. A lawn chair or recliner is helpful.
You can focus your attention on the eastern sky, since the meteors will seem to come from the constellation of Perseus, which rises in the east around midnight. That said, you do not need to know where to find the constellation of Perseus. Watch the east, but also scan the entire sky, since these streaks can appear anywhere.
Planets in August
Throughout August, Venus will emerge in the west as it gets dark around 7:30 p.m., about 15 degrees above the western horizon (a little more than the width of your fist at arm’s length). Throughout the month Venus sets around 9 p.m. Venus is hard to miss; at minus 3.9 magnitude it’s the brightest dot of light in the sky. Look for the beautiful sight of a slender crescent moon close to Venus on the evening of Aug. 9; the moon will be about four degrees to the left of Venus, or the width of two fingers held at arm’s length.
With Venus gone by 9 p.m., Saturn is the only planet in the middle part of the night. Look for Saturn in early August about halfway up in the southwest at dusk, setting in the west just before midnight. By the end of August, Saturn will be only a third of the way up in the southwest at dusk and will set just before 10 p.m. It shines at 0.6 magnitude, about as bright as a really bright star.
Saturn continues to make a nice triangle with two of the brightest stars, Arcturus and Spica. Bluish-white Spica, to the lower right of Saturn, is a little dimmer than Saturn. Arcturus, a yellow star, is brighter than both Saturn and Spica. Arcturus is to the upper right of Saturn. On the night of Aug. 12, look for the waxing crescent moon below Saturn. Saturn, the moon and Spica will make a lovely triangle.
Jupiter is by far the brightest morning planet in August. At the start of the month Jupiter rises at 3:45 a.m. in the east-northeast, shining at minus 2 magnitude. The planet will be about 15 degrees above the horizon (the width of your fist at arm’s length) as day starts to break around 5:10 a.m. By the end of August, Jupiter rises just after 2 a.m. and is halfway up in the east at daybreak. At minus 2, Jupiter is brighter than any other dot in the summer morning sky. Jupiter, as it rises in the east, is just to the left of Orion the Hunter. Look for the waning crescent moon next to Jupiter on Aug. 31.
In early August, Mars appears just below Jupiter in the morning sky, but the red planet is several dozen times dimmer than Jupiter. Mars rises in the east around 4:15 a.m. in early August and is about 15 degrees above the horizon at dawn. By the end of the month, Mars rises at 3:40 a.m. and is about 25 degrees up in the east at dawn.
Mercury joins Mars and Jupiter in the early-morning sky for the first part of August. Mercury appears below the other two planets in the east in the hour or so before daybreak. On Aug. 1, Mercury rises in the east at 4:45 a.m. and shines at minus 0.1 magnitude, brighter than all but the very brightest stars. Mercury will be about 10 degrees above the horizon when it fades into the dawn light about 5:30 a.m.
For the next two weeks of August, Mercury rises a little later each day but also increases in brightness. By Aug. 5, Mercury rises at 4:40 a.m., shines at minus 0.6, and is washed out in the dawn by 5:45 a.m. By Aug. 10, Mercury rises just after 5 a.m., shines at minus 1 magnitude, and is lost in dawn around 5:45 a.m. After that, it will be harder to see Mercury since there is a small window between when it rises and when day breaks.
For the first half of August, Mercury, Mars and Jupiter form a line in the eastern sky just before dawn, with Jupiter on top and the brightest; Mars in the middle, and by far the faintest; and Mercury on the bottom. Look east about 5 a.m. in the first days of the month. Jupiter and Mercury are about 12 degrees apart, with Mars in the middle. On the mornings of Aug. 3 and 4, look for the waning crescent moon amid the planets.
By Aug. 8, the two brighter planets are 20 degrees apart, with fainter Mars still in the middle. After that, with Mercury lower at dawn, it will be harder to catch the trio.
August Sky Map
This map is good for 11 p.m. in early August and 9 p.m. at the end of the month.
In the south, look for Scorpius in the southwest. To its left, Sagittarius the Archer is almost due south. The constellation is also called The Teapot; the eight stars that make the core of the constellation are quite bright.
To the left of Sagittarius is a much fainter zodiac constellation, Capricornus the Sea Goat. Its shape has been compared to the Joker’s smile, and to a bikini bottom.
High overhead we have the Summer Triangle, made of one bright star pulled from each of three constellations: Vega from Lyra the Harp, Deneb from Cygnus the Swan, and Altair from Aquila the Eagle.
In the north, look for the Big and Little Dippers, with Draco winding its way between the two. The time of this map is one of those rare moments when both the Big Dipper and Cassiopeia can be seen in the islands at the same time. The two constellations are on opposite sides of the North Star, and usually one constellation is up and the other is down.
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Mike Shanahan is director of Education, Exhibits and Planetarium. For more information, go to www.bishopmuseum.org/planetarium/planetarium.html Opens in a new tab
