September 8: Before sunrise, locate the thin waning crescent moon (28.0 d, 2%) 1.8° to the upper left of Regulus with Mercury 4.4° below the star. Mercury (m = −1.2) is only 4.5° up in the east-northeast 30 minutes before sunrise. You’ll need a clear horizon and binoculars to see the trio in bright twilight.
September 6: In the predawn eastern sky, the waning crescent moon (26.0 d, 15%) is on a virtual line that connects the Gemini Twins, Castor (α Gem, m = 1.6) and Pollux (β Gem, m = 1.2). The moon is 9.2° from Pollux. Thirty minutes before sunrise, with binoculars, look in the east-northeast for Mercury (m = −1.1) 1.2° to the left of Regulus. Mercury is 6.5° up in the sky.
In the evening sky, Saturn’s retrograde ends. It is 5° to the upper right of Kaus Borealis (λ Sag, m = 2.8), the star at the top of the lid of the Teapot of Sagittarius, and 45° from Jupiter. Mars and Jupiter have the same visual brightness (m = −1.9). Because they have distinctly different colors, do they appear to be the same brightness to you? While they are over 70° apart, it is not appropriate in formal astronomy to compare respective objects’ brightness, but it is a fun activity. Look near the end of twilight because they have nearly the same altitude early in the evening.
September 1: Mercury (m = −9) is 10° up in the east-northeast, 30 minutes before sunrise. It is approaching a conjunction with Regulus (α Leo, m = 1.3). This morning Regulus is 7.8° below Mercury, and very difficult to locate, even with optical assistance and a perfect horizon.
In the evening sky, for most of the month, Venus (m = −4.7) and Spica (m = 1.0) set at nearly the same time, 85 minutes after sunset this evening. As they separate, Venus moves farther south. (Recall that the farther north an object the longer it stays in the sky.) As they slide into twilight the largest time gap in their setting times is 15 minutes. Jupiter (m = −1.9) is 24° to the upper left of Venus. (If the Martian dust storms subside,) At 10 p.m. CDT, when Mars is near the meridian about 22° up, it may provide excellent telescopic views. Mars moved into the boundaries and in front of the sidereal backdrop of Capricornus.
Look for 5 planets during the month. From mid-northern latitudes, they are not visible simultaneously. Look for Mercury about 30 minutes after sunset with binoculars, then wait for Mars to cross the southeastern horizon. Four bright planets then span the sky from Mars to Venus. Mars reaches its opposition later in the month. The planet is closer than it’s been since 2003.
July opens with the waning gibbous moon in the south-southwest. Mars, now the second brightest planet, is 25° up in the south-southwest, 5.8° below the moon. At the same time, Saturn is 10° up in the southwest. With both planets near their oppositions, they appear in the southeastern sky during the evening and move westward during the night. During the early evening, four bright planets are arched across the sky, with the trio of bright outer planets in retrograde.
One hour after sunset, brilliant Venus stands 14° up in the west. Venus is 9° to the lower right of Regulus. Watch Venus close in and pass Regulus during the first 9 days of the month. At this hour, dimmer Mercury is 4° up in the west-northwest, setting nearly 90 minutes after sunset. Use binoculars to locate it. This speedy world approaches its greatest elongation during the first half of the month.
Meanwhile, bright Jupiter, 82° to the upper left of Venus, is 33° up in the south. This giant planet is 2° west of Zubenelgenubi. Saturn, just past its opposition and retrograding above the Teapot of Sagittarius, is 13° up in the southeast, 52° to the lower left of Jupiter.
Mars, racing toward its opposition later in the month, rises in the southeast 117 minutes after sunset. The Red Planet, retrograding in Capricornus, appears 34° to the lower left of Saturn. Start looking for the five naked eye planets during the early evening. Look for Mercury during twilight, then wait for Mars to clear the southeast horizon. Here are the highlights for the first half of the month:
July 1: As the sky darkens, Venus is 9° to the lower right of Regulus. Mars rises 117 minutes after sunset this evening. The waning gibbous moon is 15° to the left of the planet.
July 2: The Venus-Mercury gap is 16.6°. Mercury sets 90 minutes after sunset, its maximum setting interval after sunset for this apparition. The Venus-Regulus gap is 8° this evening. Watch Venus close the separation during the next several evenings: 07/03, 6.9°; 07/04, 5.7°; 07/05, 4.7°; 07/06, 3.6°; 07/07, 2.6°; 07/08, 1.5°.
July 4: The Venus-Mercury gap is 16.2°. Mercury’s brightness is fading fast as it approaches its greatest elongation. This evening its apparent magnitude is 0.2, but it is appearing in bright twilight.
July 6: The moon is at its Last Quarter phase at 2:51 a.m. CDT. Earth is at aphelion 94.5 million miles from the sun at 11:46 a.m. CDT.
July 9: Venus is closest to Regulus this evening, 1 degree. The planet appears to the upper right of the star. Watch the gap widen during the next several evenings as Venus moves away and toward Spica. Venus has a conjunction with Regulus in about 13 months when they are near their solar conjunctions, both hiding in bright sunlight. On October 3, 2020, Venus, 22° up in the morning sky at 90 minutes before sunrise, appears 33’ below the star. On the previous morning, Venus is 36’ above Regulus.
July 12: Mercury is at its greatest elongation, 26.4° east of the sun at 12:29 a.m. CDT. Mercury is only 13° above the horizon at sunset. The Venus-Mercury gap is 16.4°. Venus is now 3.4° past Regulus. The gap grows about 1° each evening. The moon is at its New phase, 9:48 p.m. CDT.
July 14: Not long after sunset look for the waxing crescent moon 2.1° to the left of Mercury with binoculars. Mars passes 1.1° north of Psi Capricorni.
July 15: Venus passes 1° to the upper right of Rho Leonis. The waxing crescent moon is between Venus and Regulus, 1.5° to the lower right of Venus and 5.1° to the upper left of Regulus.
At mid-month, Venus continues to dominate the evening sky with its brilliance. At 65 minutes after sunset, Venus is 11° up in the west, setting about an hour later. Venus is now 6.5° to the upper left of Regulus. On July 15, the waxing crescent moon is 1.5° to the lower right of Venus. Mercury, now past greatest elongation and fading quickly into the sun’s glare, sets 71 minutes after sunset. Use binoculars to catch it in bright twilight. Jupiter, near Zubenelgenubi, is 30° up in the south-southwest. Saturn, 19° up in the south-southeast, is 51° to the lower left of Jupiter. Mars, the second brightest “star” and rising 65 minutes after sunset, is approaching its perihelic opposition. It is 18° up in the southwest 2 hours before sunrise. Here are the highlights for the second half of the month:
July 16: The waxing crescent moon is 11.9° to the upper left of Venus. The Venus-Regulus gap is 7.7° and growing each day.
July 17: Jupiter’s retrograde ends 2° west of Zubenelgenubi. Watch Jupiter move eastward toward the star during the next month. The waxing crescent moon is 24.8° to the upper left of Venus. If you’ve not looked for all five naked eye planets, start looking for Mercury, 30 minutes after sunset with binoculars.
July 18: The waxing crescent moon is 9.2° to the upper right of Spica. During the next several nights, start looking for some Perseid meteors before the moon approaches its full phase, after midnight, and before morning twilight begins.
July 19: The moon is at its First Quarter phase, 2:52 p.m. CDT. This evening the moon is 13.3° to the right of Jupiter.
July 20: Today is the 49th anniversary of Apollo 11’s historic moon landing. This date also marks the 42nd anniversary of the Viking 1 landing on Mars. The waxing gibbous moon is 3.5° above Jupiter this evening.
July 22: The waxing gibbous moon is 8.4° above Antares.
July 24: This evening the waxing gibbous moon is 1.9° to the upper right of Saturn.
July 27: Mars (m=-2.8) is at opposition. The Full Moon is 7° to the upper left of Mars. The moon reaches its Full phase, 3:20 p.m. CDT. Mercury (m=1.9) 32 minutes after sunset during early twilight.
July 31: Earth and Mars are closest (closest approach), 35.7 million miles away.
The month ends with four bright planets lined up across the early evening sky. Brilliant Venus is 9° up in the west 70 minutes after sunset. Mars is 7° up in the southeast. Mars retrogrades until August 27. It is 30° to the lower left of Saturn, 23° up in the south-southeast, above the Teapot of Sagittarius. It retrogrades until September 6. This ringed wonder is 49° to the left of Jupiter. Jupiter is 26° up in the southwest, 1.5° to the right of Zubenelgenubi. Watch this giant world narrow the gap to the star and pass it next month. Jupiter is 50° to the left of Venus.
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.
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.
Click through this short slide show to see Venus, Mercury and the Moon this evening.
Brilliant Venus shines from the western sky this evening. Now setting nearly 90 minutes after sunset, this evening planet appears higher each evening at the same time.
Dimmer Mercury is 4.5 degrees to the right of Venus. Binoculars help finding its location. It is rapidly diving into bright twilight and fading in brightness. On April 1, it passes between Earth and Sun, and moves into the morning sky,
The 4.5-day old crescent moon appears 38 degrees above Venus this evening. Watch it appear higher in the sky, more distant from Venus, and with a growing phase as it continues through its celestial path.
The articles that follow provide details about the planets visible without optical assistance (binoculars or telescope):