Many beautiful events involving the moon and planets—against a striking background of stars—will reward early risers this July.
Predawn skies feature a display of the three bright outer planets, all easily visible to the unaided eye. The best time to look throughout the month is about 75 minutes before sunrise. At that time, Jupiter, gleaming at magnitude -2 in east-northeast to east, appears as the brightest “star” in the sky. The other two planets glow at first magnitude—or only 1/16, or 6 percent—as bright as Jupiter. Reddish Mars appears to the upper right of Jupiter, by 22° on July 1. The gap between these two planets decreases by half a degree daily, so Mars-Jupiter will appear 15° apart by July 15, and 7° apart at the month’s end. Two weeks later, on Aug. 14, Mars will pass only 0.3° north of Jupiter, for the most impressive planetary pairing of this year.
This year, Mars joins Jupiter in the constellation Taurus, the Bull, from July 12 through Sept. 5. Jupiter, which takes nearly a dozen years to circle the sun, entered Taurus in late April 2024 and will remain within its boundaries until June 2025. Taurus is noted for its two fine star clusters, the Pleaides and the Hyades, impressive to the unaided eye, and especially so when using binoculars. First-magnitude Aldebaran, marking the Bull’s reddish eye, completes a V-shaped pattern with the Hyades, constituting the head of Taurus, with all its stars fitting within a single field of view of binoculars.
Saturn stands off by itself, in the south-southeast to southwest, in the predawn sky during July. A telescope reveals the rings, appearing almost needle-like at low magnifications, as they’re tipped at an unusually small inclination of 2° to 2.4° from edge-on this month.
The waning crescent moonsweeps through the field of Mars, the Pleiades, Jupiter, Aldebaran and the Hyades on July 1-3 and July 29-31, creating especially beautiful vistas on those six mornings. Watch also for these events:
July 4, one hour before sunrise: The old moon—3% full and at its northernmost point this month—rises in the northeast to east-northeast, 17° to the lower left of Jupiter. The span of four solar system bodies—Saturn, Mars, Jupiter and the moon—is 96° long. (Faint Uranus and Neptune also sit within the lineup.)
July 8-22, about 1 1/2 to 2 hours before sunrise: Uranus appears within 5° of Mars, within same binocular field. Mars is moving 0.7° per day against background stars. Look for 5.8-magnitude Uranus 4.8° to the lower left of the red planet on July 8, and 4.6° to the upper right of Mars by July 22. They’ll appear closest on July 15, when Uranus appears within 0.6° north (to the upper left) of Mars.
July 9 and 19, about 1 1/4 hours before sunrise: Jupiter passes within 4.8° north of Aldebaran, a once-in-12-years event. Jupiter moves slowly, and so remains within 5° of Aldebaran July 3-16.
July 21, about 1 1/4 hours before sunrise: The full moon is low in the southwest. Mars passes within 4.8° south of third-magnitude Alcyone, brightest member of the Pleiades. Six solar system bodies—the moon, Saturn, Neptune, Uranus, Mars and Jupiter—span 133°. Follow the moon daily through Aug. 3, and watch it sweep past the other bodies by July 31.
July 30, about 1 1/4 hours before sunrise: Mars is 5° from the moon and 7.5° from Jupiter, while Aldebaran forms a nearly isosceles triangle with the two planets, about 6° from each.
On Aug. 1, Mars and Aldebaran have spread to 5.3° apart, while Jupiter stands 6.5° to the lower left of both reddish objects, forming an isosceles triangle.
By the closing week of July, Orion, with his two bright stars Betelgeuse and Rigel—and the vertical line of three stars marking his belt midway between them—emerges low in the eastern, early twilight morning sky, below and to the right of the triangle of Jupiter, Mars and Aldebaran. The scene is well described by Robert Frost in the opening lines of his poem, “The Star-splitter”:
You know Orion always comes up sideways.
Throwing a leg up over our fence of mountains.
Other bright stars in the morning twilight sky are zero-magnitude Vega in the northwest, accompanied by Altair and Deneb, completing the Summer Triangle; Fomalhaut, mouth of the Southern Fish, below Saturn; zero-magnitude Capella in the northeast; and the “Twin” stars of Gemini, Pollux and Castor, 4.5° apart, far below Capella. Confirm the Twins by finding them about 6° to the left of the waning crescent moon on Aug. 2.
Evenings: Both inner planets, Mercury and Venus, set during dusk twilight in July, and require binoculars for a reasonable chance for a successful sighting. That’s especially true for Venus, to the upper left of the recently set sun, by less than 8° on July 1, to 16° on July 31. Using binoculars, soon after sunset, scan the horizon to the left of the sunset point. You’ll need very clear skies and an unobstructed view.
Setting later in twilight, Mercury will be easier to see than Venus. Its magnitude fades from -0.5 on July 1, to 0.0 on July 12, to +0.5 on July 24, and +1.0 on Aug. 1. Remember that a fading of one magnitude corresponds to a 60 percent loss of brightness! On July 7, Mercury will appear 3°-4° to the lower right of the crescent moon, and climb highest, but still only a few degrees up in the west-northwest in mid-twilight, the following weekend.
Skipping Venus and Mercury—which don’t impress, because they’re currently deep in twilight—the most prominent evening stars are golden Arcturus, high in the southwestern sky, and blue-white Vega, ascending in the east-northeast. Altair and Deneb complete the Summer Triangle with Vega.
During July 1-7 at nightfall, the sky is dark and moonless for fine Milky Way viewing, and for three nights more, after moonset and before midnight.
At dusk on July 8 and 9, the waxing crescent moon appears 6° from Regulus, heart of Leo, the Lion.
On Saturday, July 13, as seen from Palm Springs, the star Spica is occulted by the leading dark edge of the moon in daylight, at 7:43 p.m.—a difficult event to observe, even with optical aid. Spica is still hidden by the moon at sunset, and emerges along the moon’s bright, sunlit edge at 9:02 p.m. The sky would be dark enough to allow seeing Spica, except for its closeness to the moon’s sunlit edge, so a telescope is recommended. Later in the evening, as the moon continues eastward, Spica will become visible to the unaided eye, to the moon’s lower right.
On the night of July 20-21, the moon is full. Thereafter, the moon rises later each evening, and by July 24, it is well below the horizon at nightfall, and the sky will again be dark for Milky Way viewing.
The Astronomical Society of the Desert will host a star party on Saturday, July 6, at Sawmill Trailhead, a site in the Santa Rosa Mountains at elevation 4,000 feet. For dates and times of other star parties, and maps and directions, visit astrorx.org.
The Abrams Planetarium Sky Calendar is available by subscription from www.abramsplanetarium.org/skycalendar. For $12 per year, subscribers receive quarterly mailings, each containing three monthly issues.
Robert Victor originated the Abrams Planetarium monthly Sky Calendar in October 1968 and still helps produce an occasional issue. He enjoys being outdoors sharing the beauty of the night sky and other wonders of nature. Robert Miller, who provided the evening and morning twilight charts, did graduate work in planetarium science, and later astronomy and computer science at Michigan State University, and remains active in research and public outreach in astronomy.
