For about a month near the summer solstice, five planets are visible during the early evening, but they are not easily visible simultaneously from mid-northern latitudes. As the sky darkens a parade of planets extends across the sky from brilliant Venus in the west to Mars in the southeast. The “X” factor of seeing 5 planets simultaneously is Mercury. It reaches its greatest elongation on July 12, although Mercury is visible throughout its apparition.
For more southerly locations in the United States and farther southern latitudes, see this article: 2018: Five Planets Visible at Once
Here’s how to look for the five planets:
June 16, 2018: Start looking for Mercury early it its apparition, although the rising time for Mars is much later. From an observing location with a clear horizon, locate the speedy planet Mercury 30 minutes after sunset. Mercury sets 63 minutes after sunset, 15 minutes before Nautical Twilight (sun’s altitude is -12°). Mars rises in a dark sky nearly 3 hours after sunset. At 30 minutes after sunset on this evening, Venus is 25° to Mercury’s upper left. The waxing crescent moon (3.3 days old) is 7.9° beyond Venus.
July 2: Again with binoculars first locate Mercury 10° up in the west-northwest 30 minutes after sunset with brilliant Venus 16.6° to Mercury’s upper left. Regulus is 8.1° beyond Venus. Mars touches the east-southeast horizon 25 minutes after Mercury sets and 15 minutes before the end of twilight.
July 12: At sunset, Mercury is 13° up in the west-northwest. Thirty minutes later, it has an altitude of only 8.5° with brilliant Venus 16.4° to its upper left. Venus is 3.4° beyond Regulus. Mercury sets 78 minutes after sunset and Mars touches the southeast horizon at the same time. Locate Mercury, then wait until Mars clears the east-southeast horizon.
July 17: The best evenings for seeing all five planets are around this date, but you’ll need optical assistance. Thirty minutes after sunset, dimmer Mercury is 5.1° above the horizon. Mercury is dimmer as the apparition continues so optical aid is needed to first locate it. Regulus is 9.5° to the upper left of Mercury with Venus 8.5° beyond the star. Mars rises six minutes before Mercury sets, although both are low in the sky. Twilight lingers for over 2 hours at this time of the year at mid-northern latitudes.
On July 17, 2.5 hours after sunset and after Mercury sets, the planet parade arches across the southern sky. Brilliant Venus sparkles 5° up in the west and Mars is 5° up in the southeast. Saturn is 32.8° to the upper right of Mars, above the Teapot of Sagittarius. Jupiter is 50.8° to the west of Saturn and 1.8° to the west of Zubenelgenubi. The moon (5.0 days old) is nearly between Venus and Jupiter.
Another opportunity to see five planets simultaneously, from mid-northern latitudes, occurs in the morning near the time of the summer solstice in 2020. While these groupings are infrequent, they provide magnificent displays of the solar system’s beauty.
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