This August features a gathering of planets just above the sun at dusk, and the return of the most famous meteor shower.
There is a chance to catch all five naked-eye planets at the same time in the early evening, and Venus and Jupiter have their closest gathering since the year 2000 at the end of the month.
In mid-July it became possible to see all five naked-eye planets in the early-evening sky; this phenomenon continues through August. The situation is divided into two groups: Jupiter, Venus and Mercury hanging low in the west at dusk, and Saturn and Mars shining in the south. Since the western planets set by 8 p.m., you will have only about 30 minutes, from 7:30 to 8 p.m., to collect the full set of planets.
The two brightest planets, Venus and Jupiter, gather low in the west with Mercury at dusk throughout August. To see this gathering in early August, look west between 7:15 and 8 p.m. Venus shines brilliantly in the west, at minus 3.88 magnitude; by the time you pick it out, around 7:15 p.m., it will be only about 10 degrees above the west horizon, or the width of your hand at arm’s length. Venus sets by 8 p.m.
Early in the month, draw a line from Venus up to Jupiter, the second brightest dot in the sky. As it gets dark, look for Jupiter about two hand-widths above Venus, shining at minus 1.75 magnitude. Jupiter sets around 9:15 p.m. in early August, well over an hour after Venus.
If you draw a line from Venus to Jupiter in the first week of August, the planet Mercury will be in between the two brighter planets. Mercury shines at around zero magnitude, similar to a very bright star. It appears closer to Venus than Jupiter at the start of the month, and almost exactly in between the other two planets by Aug. 7.
Of particular note: Look for the slender crescent moon low in the west on Aug. 4; it will be just to the left of Mercury. The following night, the moon will be just to the left of Jupiter.
From Aug. 8 through 23, the three planets will appear to change from a line into a triangle. By Aug. 21, they will make a striking triangle: Venus on the bottom, Jupiter five degrees above Venus, and Mercury about six degrees (three fingers) to the left of Venus. The whole tight triangle should be visible by 7:30 p.m., low in the west, and sets at 8 p.m. By Aug. 23, the three planets make a compact, almost equilateral triangle.
From then to the end to the month, Venus seems to get closer and closer to Jupiter; on the night of Aug. 27, the two planets are side by side in a tight gathering, less than a fourth of a degree (half the width of the moon) apart. This will be the tightest gathering of the two brightest planets since the year 2000; it may appear that they are practically fused into a single light. On this night, as throughout the month, you only have about 45 minutes to catch this lovely sight, from dusk until the planets set together at 8 p.m. Make sure you have a clear, flat horizon to view this close gathering.
The other two naked-eye planets, Saturn and Mars, are also visible in the evening sky this month. As it gets dark in early August, look south; Mars is the orange dot to the right of the orange star Antares, the brightest star in the constellation of the Scorpion. Saturn is directly above Antares; the two stars and the planet form a triangle at the start of August.
As the month goes on, Mars will appear closer each night to a line drawn from Antares to Saturn; due to this, what was a nice triangle on Aug. 1 will squish into a straight line running from Antares to Mars to Saturn by Aug. 23. (This is the configuration of Antares, Mars and Saturn you see on our August sky map, with a straight line between the orange star Antares, the orange planet Mars, and Saturn.)
From Aug. 24 to the end of the month, Mars will appear a little more to the left of Antares and Saturn night by night; by the end of the month, there is another nice triangle between the three dots of light, now with Mars on the triangle’s left side.
In early August, Mars sets by 1 a.m. and Saturn sets by 1:45 a.m. By the end of the month the two planets set together, at midnight.
Look for the moon, around first quarter, next to Mars and Saturn on the nights of Aug. 10 and 11.
Perseid meteor show
The Perseids are the most famous meteor shower of the year, with up to 80 an hour. The peak of the shower occurs early in the morning on Aug. 12, from 12:01 a.m. until dawn, and again early in the morning of Aug. 13, 12:01 a.m. until dawn. The moon should not be too much of a problem this year; it is waxing gibbous during this shower’s peak, setting by 1 a.m. on Aug. 12 and before 2 a.m. on Aug. 13. So, the moon gets out of the way right as the shower starts picking up.
To view shooting star showers, just find a dark location (with as little city light as possible) and get comfortable; a lawn chair is a good idea. While many meteors seem to be coming from the constellation of Perseus, which rises in the east around midnight, check the entire sky for streaks of light. As with all meteor showers, the viewing of the Perseids will be better after midnight.
These repeating annual events are caused as the Earth enters into debris left over from a specific comet, in this case, Comet 109 P Swift Tuttle. With the Perseids, this comet debris is located in the direction of the constellation of Perseus the hero; because the streaks of light seem to come from that part of the sky, the shower is called the Perseids shower.