From the June 2024 issue

Sky This Month: June 2024

June’s pre-dawn sky finds six planets strung along the ecliptic. It’s a great time to become acquainted with many planets all in one go.
By and | Published: June 1, 2024 | Last updated on June 3, 2024

June’s pre-dawn sky finds six planets strung along the ecliptic, spanning 72° on the 1st. In order of increasing elongation from the Sun, they are Jupiter, Mercury, Uranus, Mars, Neptune, and Saturn. A 24-day-old waning crescent Moon joins the line of objects, 16° east of Saturn. It’s a great time to become acquainted with many planets all in one go, and during nice weather to boot.

Some of the planets switch places early in the month, while the Moon wanders across the line over the span of four days. Most are visible to the unaided eye, though Mercury is challenging as its elongation quickly diminishes in bright twilight after the 1st. Uranus and Neptune both require binoculars to spot.

Let’s take a look at the spread of planets, starting with the first to rise.

Saturn lies in eastern Aquarius and shines at magnitude 1 on June 1. It rises just before 2 a.m. local daylight time and stands 1.5° east of Phi (ϕ) Aquarii. It extends this distance to 2.1° by June 30, when the ringed planet reaches its stationary point. Saturn and a gibbous Moon lie less than 3.5° apart on the morning of June 27.

You can see practically the full disk for the first time in 14 years. It spans 17″ and the wide axis of the rings stretches almost 40″. We are a year away from the ring-plane crossing, which occurs in March 2025. Now that the ring plane is almost edge-on, the satellites of Saturn appear to criss-cross in front or behind the planet. Titan, the brightest of Saturn’s moons at magnitude 8.6, orbits the planet every 16 days. It transits Saturn’s southern hemisphere on June 14, beginning shortly after 4 a.m. CDT. With dawn approaching on the East Coast and Saturn 30° high in the Midwest (and lower farther west), its visibility will be affected by local seeing conditions.

Titan’s transit lasts four hours, with the latter parts visible from the western U.S. The fainter satellite Rhea begins a transit at 4:20 a.m. MDT, its shadow appearing behind Titan as both moons transit — quite an extraordinary alignment. Rhea is a small satellite and shines at only magnitude 10, so it’s very difficult to see against the bright background of Saturn. High-speed video and image-refining techniques should capture it.

Eight days later, on June 22, Titan passes behind Saturn in an occultation. It approaches the northwestern limb of the planet and disappears just before 4 a.m. EDT, taking a few minutes to become fully occulted. Given local seeing conditions and its altitude, see how long you can keep track of Titan before it’s gone. Meanwhile, magnitude 10.5 Tethys skims along the northwestern edge of the rings.

A nice challenging observation occurs the morning of June 25, when Dione (magnitude 10.6) is visible off the western limb of Saturn. The moon crosses into the planet’s shadow around 3 a.m. EDT and disappears behind Saturn’s disk at 3:43 a.m. EDT. Meanwhile, Tethys is transiting in front of Saturn and may be visible in the very narrow dark shadow just south of the rings on the planet.

You’ll often see the moons skimming the edge of the rings, a perspective effect that is intriguing to watch. Tethys, Dione, and Mimas congregate very close to the rings on the morning of June 21. Their relative motion can be spotted within 15 minutes.

Iapetus orbits at a much greater distance from Saturn than the other moons and takes just over 79 days to perform a complete loop. Iapetus also varies in brightness as it orbits, a result of the difference between its bright and dark hemispheres. It shines near 10th magnitude at western elongation and closer to 12th magnitude at its eastern limit. This month, Iapetus reaches its fainter eastern elongation in mid-June (the 17th), standing 8.5′ from the planet.

Neptune is located about 10.5° east of Saturn and 9° southwest of the Circlet of Pisces. The 5th-magnitude star 27 Piscium is a useful guide to the 8th-magnitude planet. Scan the region with a pair of 7×50 binoculars; find Saturn and look two fields of view to its east. Look for a parallelogram of four stars in the 4th- to 5th-magnitude range. 27 Psc is the northernmost bright one; you’ll find the much dimmer Neptune about 2° north-northeast of it. Neptune remains near its stationary point this month — it is moving constantly but the combined motion with Earth’s orbit makes it appear to stand almost still.

If you need a brighter guide to finding Neptune, look no further than the waning gibbous Moon on June 28. Neptune rises at 12:30 a.m. local daylight time, with the Moon just to its southwest for observers in the eastern half of the U.S. At 3:30 a.m. EDT, Neptune stands 0.7° due north of the Moon. As the morning progresses, the Moon moves northeastward, so an hour later, it’s west of the planet. The distance slowly increases and by dawn in the Midwest, they’re just over 1° apart.

Mars is up next, rising shortly before 3:30 a.m. local daylight time on June 1. The Red Planet glows at magnitude 1.1. In the pre-dawn sky of June 2, it stands 6.5° east of the waning crescent Moon in eastern Pisces. By June 6, Mars is within 0.5° of Omicron (ο) Psc, a 4th-magnitude star that glows more than 100 times brighter than our Sun and lies nearly 300 light-years away. The star is an aging sun that appears orange in telescopes. So does Mars, although the planet’s color is due to the hue of its surface dust. How do their colors compare?

Mars soon moves into Aries (on the 10th) and skips across two-thirds of this constellation by June 30. By this time, the Red Planet rises before 2:30 a.m. local daylight time Through a telescope Mars spans 5″, and if you can see enough detail, note the 91-percent-lit disk. Mars is just over six months from opposition and will grow in prominence for the rest of the year.

Uranus rises next and on June 1 it’s up by 4:45 a.m. local daylight time. The twilight strongly interferes. However, note that Uranus and Mercury are 2.5° apart, and Mercury shines at magnitude –0.9. If you can spot Mercury, try using binoculars and scan westward to spot magnitude 5.9 Uranus. This will be challenging at low elevations due to its faintness, but if you’re located above 4,000 feet or so (and the higher the better), atmospheric haze is less and you’ll have a good chance of spotting the seventh planet in twilight using optical aid.

Jupiter passed superior conjunction last month and reappears in the morning sky in June. Its visibility continues to improve throughout the month, rising earlier each day. On the 1st, the gas giant rises 20 minutes after Uranus and is easy to spot at magnitude –2. Jupiter and Mercury stand 5° apart, and you might even spot the Pleiades 5° north of Jupiter if you grab binoculars for viewing. The sky gets bright quickly and Uranus (and M45) will become increasingly difficult.

If you can’t spot Uranus on June 1, wait until the end of the month, when the ice giant rises shortly before 3 a.m. local daylight time in a dark sky. With Mars now 10° to its west and the lovely Pleiades star cluster 6° to its northeast on the 30th, Uranus is an easier target for binoculars or a telescope.

An hour later on that date, Jupiter and Mars are low in the eastern sky, with Uranus midway between them. It’s a perfect summer morning, with a waning crescent Moon standing higher in the east. Watch the sky over the following hour to see the Hyades in Taurus rising as twilight begins to roll in.

June 4 is a noteworthy but challenging date for observation, when Mercury and Jupiter are only 7′ apart in bright twilight. Mercury shines at magnitude –1.1 and Jupiter at magnitude –2 so it’s a bright pair, but they stand only 12° west of the Sun. Such a close conjunction is rare, so it’s worth trying for. As previously mentioned, higher elevations help by reducing atmospheric haze. The farther south you are, the better the chance of seeing them as well.

Mercury sinks quickly out of view and appears in the evening sky by the end of the month, standing 6° high 30 minutes after sunset at magnitude –0.7.

Meanwhile, Jupiter continues to improve — by June 30, it rises at 3:30 a.m. local daylight time and stands 5° from Aldebaran, the brightest star in Taurus. Through a telescope its disk spans 34″ and the gas giant is attended by its collection of Galilean moons: Io, Europa, Ganymede, and Callisto.

Venus reaches superior conjunction with the Sun June 4 and remains invisible this month.

The Northern Hemisphere experiences its summer solstice on June 20, when the Sun reaches its northernmost declination in the sky. This occurs at 4:51 p.m. EDT.

Rising Moon: Celebrate!

Enjoy the “earthiness” of a nearly Full Moon on the summer solstice. This date — the longest day and the shortest night of the year — is strongly tied to the progression of the seasons and cherished by cultures worldwide. Consider seeking out your local Indigenous community — their sky is different than the official IAU constellations. You might even feel more of a connection to their stories than to the classical Greek mythology.

Adding to the festivities, the Strawberry Full Moon shines on the 21st. Although more than 24 hours after the solstice, the pairing will still make the news. It’s reasonably common if you break the arbitrary hard lines of the Western calendar: Full Moons fall on the 18th in 2027, the 23rd in 2032, the 20th in 2035, and the 22nd in 2043. More will follow.

Because the Sun and Moon are opposite each other in the sky, it’s fairly well known that the Full Moon rises at sunset and sets at sunrise. There is little surprise to be had at this at lower latitudes, but farther north it’s notable how late the moonrise is. For some places, thanks to the daylight saving protocol, the Full Moon doesn’t rise until after midnight! The extra lag is due to the current alignment of the lunar orbit’s 5° tilt to the rest of the planets’ (the ecliptic plane). Low this summer, Luna is clipping Antares, but will sail well above it nine years from now.

Meteor Watch: Glowing display

June is a quiet month for meteors, with no major showers occurring. The so-called sporadic background rate from random meteors or remnants of long-gone showers reveals up to seven meteors per hour, and always keep a look out for the occasional fireball.

Noctilucent clouds are glorious features of the summer sky from northern latitudes. They are preferentially seen from latitudes of 55° north to 70° north and are located more than 10 times the height of ordinary cirrus clouds. They have an iridescent pearly glow and remain in sunlight long after the Sun has gone down. Ice crystals forming on high-flying dust particles generate the spectacle, and time-lapse photography reveals beautiful flows produced by extremely high wind patterns. They don’t appear every night, but always cast a glance to the northern sky to see if they’re present.

Comet Search: All night short

Well before astronomical twilight ends, have your scope on Comet 13P/Olbers, low in the northwest. At 8th magnitude, it’s the brightest of a trio of comets tonight — but sadly, it’s quickest to set. Take in the modest star cluster NGC 2281 along the way. The two make a wide-field pairing 2° apart from the 8th to the 10th. Never seen a lynx? The sky version is just as camouflaged, so at the end of the month, use the feet of Ursa Major to close in on Olbers.

If it’s too faint for the eye, the bluish ion tail may be the prize for imagers. The classic broad fan shape of the comet goes edge-on as Earth passes through its orbital plane June 17 to 18. We should be treated to an anti-tail, a trick of perspective where one of the tails appears to point back to the Sun.

Quickly slew to the south side of the Virgo galaxy cluster, already west of the meridian, to check out Comet C/2023 A3 (Tsuchinshan–ATLAS), glowing about 9th magnitude and masquerading as a galaxy.

A treat for visual and observers and imagers alike, the Fireworks Galaxy (NGC 6946) and its neighboring star cluster NGC 6939 host 10th-magnitude Comet C/2021 S3 (PanSTARRS) from the 13th to 15th. This gathering may test your resolve in waiting for the Moon to set around 2 a.m.

Locating Asteroids: Look way up

2 Pallas is a favorite of mine — half of the time. Its orbit is tilted so much to the ecliptic (34°) that it’s often too low for me, but then the asteroid vaults out of the deep south, reaching high declinations. A nice side effect is that the Moon never interferes. As a further bonus this month, it lies just east of Corona Borealis, a straightforward star-hop from magnitude 4.1 Epsilon (ε) Coronae Borealis.

Sporting a diameter of 320 miles, Pallas checks in as the third-largest rock of the main belt. Its reflectivity, or albedo, is a pretty typical 16 percent, putting this month’s brightness at magnitude 9.3, just past opposition in mid-May. In four years, it’ll hit magnitude 6.6 with a close approach, relatively speaking.

Let the sky do the work for you: On the 1st, center your scope on Epsilon CrB, then come back 19 minutes later to see Pallas in the center of the field. By the 14th, it’s just nine minutes before the rock arrives at center stage. The best times to frame Pallas with four or five marker stars are the first week of the month and the 17th through the 21st. Each night you come back, Pallas has moved on.

To see the main-belt object shift during a single three-hour session, go for the 8th, as it closes in on a magnitude 6.6 star. The two start at a separation similar to the Double Double (Epsilon Lyrae, 3.5′), and end with a gap like beautiful Albireo (0.5′).