June mornings feature a striking lineup of solar system bodies.
On June 1, a 30 percent crescent moon sits midway between two first-magnitude planets, Saturn in the southeast, to the moon’s upper right, and Mars in the east, to the moon’s lower left. The best view is 1 to 1 1/2 hours before sunrise, before the brightening dawn interferes. The waning moon passes close to four planets in a span of six days: Saturn on May 31, Mars on June 2, and a close Mercury–Jupiter pair on June 5. But to see Mercury or Jupiter in early June, you’ll need binoculars and an unobstructed view toward the east-northeast horizon during bright twilight, closer to sunrise.
On the morning of June 3, the 12 percent crescent moon will appear 9° to the lower left of Mars; on June 4, the 5 percent moon will be 22° to Mars’ lower left. On the latter morning, wait a bit, and aim your binoculars very low in bright twilight, 14° to the moon’s lower left, and try for emerging Jupiter, with departing Mercury just one-sixth of a degree to its lower left. You’ll need perfect skies! Jupiter gets higher each morning, and will become easy to see with the unaided eye later this month. Mercury is heading toward superior conjunction beyond the sun on June 14, and will emerge into the evening sky in June’s final week.
On June 5, again using binoculars in twilight, look 36° to the lower left of Mars for the rising of a very thin, old 1 percent moon, only about 24 hours before new. If you spot this crescent, describe it and note the times you first and last observe it for future reference. (The new moon occurs the next day at 5:38 a.m.) Also on June 5, can you spot Jupiter and Mercury, rising nearly 2° apart, 4° to the moon’s lower right?
In dark, moonless skies two to three hours before sunrise from June 3-16, get fine views of the Milky Way, with its Cygnus Star Cloud—made up of stars of our own spiral arm ahead of us in our revolution around the galactic center—overhead inside the summer triangle of Vega, Altair and Deneb. By June 21, the moon, nearing full, returns to the morning sky, setting in the southwest during twilight. An impressive lineup of the moon, Saturn, Mars and Jupiter spans 162° that morning, nearly from horizon to the opposite horizon. For the rest of June and into July, Jupiter is immersed in a beautiful star field in Taurus, below the Pleiades and above Aldebaran and the Hyades. Mars will pass through the same field, overtaking Jupiter by mid-August.
On the morning of June 27, the moon will appear closely west of Saturn, occulting the planet in the daytime, after sunrise. In late June, as viewed through a telescope, Saturn’s rings appear only 2° from edge-on, an unusual aspect. On July 1-3, a waning crescent moon sweeps past Mars, the Pleiades, Jupiter, Aldebaran and the Hyades.
Jupiter appeared in solar conjunction on the far side of the sun on May 18. As a consequence of Earth’s faster orbital motion around the sun, Jupiter is emerging into the morning sky. Both inner planets pass superior conjunction on the far side of the sun this month—Venus on June 4, and Mercury on June 14. Since they orbit faster than Earth, they’ll emerge into the evening sky. At this conjunction, Mercury also happens to be at the perihelion of its orbit, so it will be very bright and will move very swiftly into visibility. With binoculars, very clear skies, and an unobstructed view of the west-northwest horizon, it’ll be possible to start seeing Mercury within a week after its conjunction, and with unaided eye before the month’s end. Venus is more leisurely, moving only 7° out from the sun by June 30, while setting only 30 minutes after sunset. The decreasing angle of the ecliptic (planetary pathway) relative to the horizon at dusk as summer progresses will slow Venus’ climb out of the bright twilight glow. But the improving geometry and Venus’ larger orbit, extending up to 47° from the sun, will make the cloud-covered planet a spectacular “evening star” later this year and into March 2025.
The summer solstice on June 20 gives us the highest midday sun and the northernmost sunrise and sunset of the year. Combined with the moon’s orbit near its maximum inclination to Earth’s equator in 2024-25, a thin crescent moon at dusk on June 7 sets unusually far north. (A hyper-thin crescent moon, only about 15 hours after new, and within 8.5° of the sun, might be caught with binoculars in early twilight on the evening of June 6.) The full moon at dusk on June 21 rises unusually far south, several degrees more so than the sun’s annual extremes. Between those dates, watch the moon pass these bright zodiacal stars in the evening sky: Pollux in Gemini on June 8; Regulus in Leo on June 11; Spica in Virgo on June 15 and 16; and Antares in Scorpius on June 19. Note Pollux and Castor, 4.5° apart, mark the top of the “spring arch,” still entirely visible in the west to northwest in early June. From left to right, its stars are Procyon, Pollux, Castor and Capella. Other bright stars at dusk are Arcturus, crossing high in the south, and the Summer Triangle of Vega, Deneb and Altair, rising in the northeast to east.
In June’s final week, watch the changing configuration of the “Twin” stars Pollux and Castor with Mercury. On June 23, Mercury is 10° below the twins, forming an isosceles triangle. On June 28, Mercury passes 4.7° (the minimum distance) south, to the lower left, of Pollux. On June 30, Mercury is 6.3° to the left of Pollux, in a straight line with twins.
Throughout the summer of 2024, the three bright outer planets put on a nice show in the predawn sky. Folks averse to waking up early to planet-gaze, take heart! Earth will overtake Saturn in September, Jupiter in December, and Mars in January 2025. Those dates mark when those planets will be at their closest and brightest—and thereafter, we’ll look back into the wake of Spaceship Earth to see them in the evening sky, joining Venus.
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.
