Midday on June 20 (12:48 p.m. in Palm Springs), the sun passes only 10 degrees south of overhead in the Coachella Valley. Summer officially begins at 2:44 p.m., when the sun is exactly over the Tropic of Cancer, east-northeast of Hawaii.
My advice: Avoid the intense light and heat of midday! Get out during the cool predawn, mostly between 90 minutes and one hour before sunrise, to enjoy the lineup of three or four naked-eye planets.
On mornings in June, Jupiter and Saturn will catch your eye, because they’re only 5-6 degrees apart, drifting across the sky from the south to southwest—Jupiter is the brighter, westernmost member of the pair—while moving little among the stars near the border of Sagittarius and Capricornus. Mars moves from Aquarius into Pisces in June, yet strangely stays fixed in the southeast those 30 mornings, while the zodiac background seems to scroll westward behind the brightening red planet.
Venus adds impressive brilliance to the predawn planetary panorama by mid-June. In Taurus, it hangs in the east-northeast, 9 degrees below the Pleiades star cluster for two weeks, June 14-27, as both rise a few minutes earlier each morning, into a darker predawn sky. Starting on July 1, Venus slowly moves across the Hyades star cluster until passing just one degree north of Aldebaran, eye of the Bull, on July 11 and 12. By then, Jupiter and Saturn will be nearly at opposition, so they’ll be getting low in southwest, almost 180 degrees from the sun.
Mars, brightening from magnitude 0.0 to -0.5, is in the southeast, 41 to 61 degrees east of Saturn. On June 5, Mars lies directly ahead of Spaceship Earth in our pursuit of the red planet, and later in the month displays its minimum gibbous phase, 84 percent full. (When we overtake Mars on Oct. 13, it will appear at opposition and be visible all night.)
Welcome Venus! After passing inferior conjunction, nearly between the Earth and sun, on June 3, Venus climbs quickly into the morning sky, to upper right of the rising sun. By June 13, it’s easy to see with the unaided eye, but very low, at morning mid-twilight. Even a few days before that date, you can use binoculars to pick out Venus’ very thin crescent in a brighter sky. While Venus is less than 15 degrees from the sun before June 13, protect your eyes by blocking the sun with a building, or looking before sunrise. By June 15, Venus rises an hour before the sun, and by June 30, two hours before.
Telescopic views: Enjoy Jupiter, with two dark equatorial cloud belts and four bright satellites discovered by Galileo; Saturn’s rings now tipped 21 degrees from edge-on; and Mars’ frozen carbon dioxide south polar cap, now extensive while it is mid-spring in that hemisphere. Syrtis Major, the largest dark marking on Mars, first seen in 1659, will be well-placed nearest to the center of the planet’s disk on June 23 at 2:52 a.m.; June 24 at 3:32 a.m.; June 25 at 4:12 a.m.; and June 26 at 4:52 a.m. To see these details on Mars more than three months before its closest approach requires high magnification, but Venus’ crescent is easy to see with low power. Watch it thicken from 5 percent on June 15, through 10 percent on June 21, to 15 percent on June 27, and 20 percent on July 2, while shrinking in apparent size as it recedes from Earth.
As for stars, the Summer Triangle of Vega, Altair and Deneb passes overhead, chasing Arcturus and Antares below the western horizon. Fomalhaut, mouth of the Southern Fish, approaches its highest position, in the south.
The waning moon, in gibbous phase, skips past Jupiter and Saturn on the mornings of June 8 and 9. A few days later, the moon—near last-quarter phase and about half illuminated—appears near Mars on June 12 and 13. On the morning of June 18, look for Venus 10-11 degrees to the lower left of an 8 percent crescent moon. On June 19, look for the last, 3 percent old moon, just 2 degrees to the lower left of Venus. It might be too difficult to spot Aldebaran in bright twilight that morning, within 5 degrees to the lower left of Venus and 3 degrees to the lower right of the moon. The moon drops out, but Venus and Aldebaran get higher each morning, spreading to 5.1 degrees apart June 22-25, as Venus ends retrograde in Taurus.
From June 21-24, the four planets Venus, Mars, Saturn and Jupiter span a minimum arc of 130 degrees across the sky. Spectacular for binoculars: On June 30, Venus, entering the Hyades star cluster, will be within 4.5 degrees to the upper right of Aldebaran; and on July 11 and 12, Venus will pass just one degree north of the red, first-magnitude star.
June evenings: Mercury on June 1 is of magnitude +0.2 and near peak altitude for this apparition, low in the west-northwest evening twilight, below the “Gemini Arch” of Procyon, Pollux, Castor and Capella. The innermost planet fades to +1.1 by June 10, when it’s 12 degrees below the sinking Twins, and completes an isosceles triangle with them. Thereafter, Mercury quickly fades, and sinks into bright twilight.
Regulus is high in the west-southwest to west; Spica and Arcturus pass through their highest points in the south; and Antares; past opposition, ascends in the southeast. Altair rises north of east to complete the Summer Triangle with Vega and Deneb farther north, to its upper left.
At the end of June, in the east-southeast, Jupiter rises a bit less than an hour after sunset, and Saturn a bit more than an hour, about 20 minutes apart. You can spot them higher in the southeast later in evening; highest in south near 3 a.m.; or in the southwest as dawn brightens.
Waxing moon in the evening: Catch the gibbous moon near Spica on June 1, and a nearly full moon close to Antares on the night of June 4-5. The moon returns to the evening sky on June 22 as a thin crescent low the west-northwest at dusk, to the lower left of Pollux and Castor. Find a fatter crescent moon near Regulus on June 24 and 25. On Saturday, June 27, the moon nears first-quarter phase, half full and 90 degrees from the sun, and is ideal for showing details through binoculars and telescopes. On the next two evenings, find Spica near the gibbous moon.
The Sky Calendar now has more than 3,000 subscribers nationwide. From its first issue in October 1968, without interruption through August 2012, I designed and co-produced the monthly Sky Calendar for Michigan State University’s Abrams Planetarium. I now do about three year. For more information and a sample, visit www.abramsplanetarium.org/skycalendar.For resources on observing Mars during 2020, visit www.abramsplanetarium.org/msta.
The star parties hosted by the Astronomical Society of the Desert are likely to be cancelled through at least June, to help limit the spread of COVID-19. To check for the eventual resumption of activities, visit the club’s website at www.astrorx.org. The Rancho Mirage Library’s Observatory is currently closed as well; watch www.ranchomiragelibrary.org/observatory.html for updates.
Wishing you clear skies!
Robert Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing informal sky watching opportunities for folks in and around Palm Springs. Robert D. Miller 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.