Junes short nights bring big sights for sky-watchers

July 17, 2024

Late spring gives way to summer in June, bringing mild nights to explore the starry sky. Unfortunately, these are the shortest nights of the year, but, if you’re an avid sky-watcher, sleep is overrated.

It’s time for the Strawberry Moon

A bright moon greets sky-watchers as June begins, with a big orb skirting the southern horizon during the month’s first weekend. The moon is full at 11:41 p.m. Eastern time on Saturday. June’s full moon is traditionally called the Strawberry Moon, marking the time of year when these delicacies ripen for harvest. It is also known as the Mead Moon, Rose Moon and Honey Moon because of the apparent color of its disk. It is the southernmost full moon of the year, and because its light has to pass through more of Earth’s atmosphere for us Northern Hemisphere dwellers, it takes on a slight amber tint.

Insomnia for die-hard astronomers?

The summer solstice occurs on June 21 at 10:58 a.m. This is the moment when the sun reaches its most northerly point in the sky and we experience the longest day of the year. In Washington, the sun is above the horizon for 14 hours and 54 minutes for several days before and after the solstice. It also means that if you like looking at the stars in a dark night sky, you don’t have much time to do so.

We use the term “twilight” to describe the afterglow of the rising or setting sun, and there are three varieties of twilight that are tabulated in our almanacs.

Civil twilight is the time when the center of the sun’s disk is six degrees below the horizon. In Washington, that is generally a half-hour after sunset or before sunrise. This is the time when objects can still be clearly seen, but we begin to lose color perception.
Nautical twilight is the time when discerning the horizon at sea becomes difficult, and it occurs when the center of the sun’s disk is 12 degrees below the horizon.
Astronomical twilight is the time when any residual glow from the sun is no longer visible; the sun is 18 degrees below the horizon. It generally occurs 90 minutes after sunset or before sunrise. Factoring in astronomical twilight, sky-watchers have just six hours to enjoy the splendors of the summer skies for the weeks before and after the solstice.

Lions and Herdsmen and Bears. Oh, my!

If you are willing to stay up past 10 p.m., several distinctive constellations will greet you on June nights. The easiest one to pick out is the “asterism,” or group of stars, known as the “Big Dipper,” which hangs high in the northern sky at the end of evening twilight. The seven stars that form its distinctive shape are part of a much larger constellation: Ursa Major, the Great Bear.

From a dark site, it doesn’t take too much imagination to see a stick figure resembling a bear, save for its preposterously long tail made up by the stars in the Dipper’s “handle.” Preposterous or not, you can follow the arc of the handle to Arcturus, the brightest star in the northern half of the sky. Arcturus is a giant star in the constellation of Boötes, the Herdsman, which looks to me more like a kite than a person.

Moving back toward the Dipper, we can use a northward-trending line from the two stars at the outer edge of the “bowl” to point out Polaris, the North Star. A southward-trending line from these same stars will bring you to Regulus, the “heart” of Leo, the Lion. Regulus sits at the base of a semicircle of stars that form an asterism called “The Sickle.” Leo’s hindquarters are marked by a right triangle, whose eastern apex is marked by the star Denebola. You can find the big cat in the southwestern sky as twilight ends.

Venus chases Mars through ‘the Beehive’

Venus still dominates the western sky throughout the month. This planet is the third-brightest object in the sky after the sun and moon, and it reaches its greatest apparent distance from the sun on June 4. You should have little trouble spotting it shortly after sunset. Venus spends much of June chasing down the more distant and fainter planet Mars. After 9:30 p.m., look above and to the left of Venus for the dimmer red-hued glow of Mars.

If you have a pair of binoculars, track down Mars on the nights of June 1, 2 and 3. During this time, the Red Planet appears to cross a well-known star cluster known as “the Beehive.” From a dark site, the cluster is visible as a hazy patch to the naked eye, but urban dwellers can get a nice view with a bit of optical aid. Venus follows Mars on June 13, passing through the northern part of the cluster. By the month’s end, both planets approach Regulus in Leo.

Yellow-hued Saturn rises after midnight for most of June and is easily seen in the pre-dawn southeastern sky. The planet’s famous rings can be seen with a good spotting telescope, but you may want to wait until later in the summer, when the planet will be in the sky all night long.

Jupiter should be easy to find in morning twilight by the middle of the month, and, by July, it will be a good target for the small telescope. The giant planet will be best seen in the fall, but early morning commuters can enjoy its companionship for the rest of the summer.

Geoff Chester is an astronomer who has worked at the U.S. Naval Observatory since 1997.

correction

A previous version of this article incorrectly said that Saturday's full moon will be at 7:39 a.m. Eastern time. It will be at 11:41 p.m. The article has been corrected.

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