The seasons transition this month with the arrival of the June solstice, heralding summer heat in the north and winter chill in the south. Sky-watchers will also be treated to the best views of the largest planet in the solar system, Jupiter, which will appear at its biggest and brightest in five years.
So mark your June calendar, and gaze skyward on the next clear night.
Venus and moon—June 1
Known affectionately as Earth’s “evil” twin, Venus is one of the brightest planets in our night skies thanks to its thick, reflective atmosphere. The planet currently hangs very low in the eastern horizon, rising only about an hour before the sun does, so the viewing window will be short.
But on the morning of June 1, Venus will be joined by a razor-thin crescent moon, making for an especially appealing sight. Try using binoculars to spot the waning crescent moon about five degrees to the right of Venus, a separation equal to about the width of your fist held at arm’s length. Both objects should be visible through binoculars in the same field of view.
Moon moves near Mercury— June 4
Just a few days after its morning visit with Venus, the moon will pop into the evening sky to skirt past another planet, tiny Mercury. Look for the moon to appear as a very slim sliver, as it will be only a day past its new phase. Star-like Mercury will sit just six degrees to its right.
Big, bright Jupiter—June 10
On this night, look for Jupiter to be at its best and brightest for the entire year. That’s because the largest planet in the solar system will officially reach opposition—meaning it will be directly opposite to the sun from our perspective and will be well lit and visible from sundown to sunrise.
Opposition also means that Jupiter will be at its closest to Earth in its orbital cycle, coming within 398 million miles of us. This will make it 11 million miles closer than last year’s opposition, so it should be stunningly bright, outshining even the nearby brilliant star Antares.
If you have binoculars or a small telescope, make sure to check out Jupiter’s retinue of moons as well as the planet’s complex atmospheric details. For those with larger backyard telescopes, watch for the famed Great Red Spot to pop into view as the planet spins on its axis. This cyclonic storm is about the size of Earth and has been raging for at least three centuries. But in the last few weeks, keen-eyed star-gazers have spotted changes in the Great Red Spot, according to Sky & Telescope. Large gaseous filaments—some measuring about 6,000 miles long—have been drawn out from the famous cyclone, visibly altering its distinctive appearance.
Jupiter in a triangle—June 15
Shortly after local sunset on the 15th, look toward the southeast for the waxing gibbous moon to form an eye-catching triangular formation with brilliant Jupiter and Antares, the brightest star in the constellation Scorpius. By the next evening, the moon will be nearly full and will jump to the other side of Jupiter, re-forming the triangle into a celestial arc.
Venus hits a bull’s eye—June 16
For a great binocular observing challenge, try to catch Venus and the bright star Aldebaran, the "eye" of the constellation Taurus, together at dawn low in the eastern horizon. Your best bet will be to find an observing location with a clear view of the eastern horizon and to start observing about 45 minutes before your local sunrise.
Mercury meets Mars—June 18
After sunset, look toward the west for a close encounter between Mercury and Mars. The two worlds will be separated by only half a degree, equal to the width of the full moon, making it the closest encounter of these two small worlds in Earth’s skies in 13 years.
Mars is five times brighter than Mercury, so the innermost planet is usually a bit more challenging to track down. But since the two worlds will be so close together on the 18th, Mercury should be much easier to find. And once both these inner planets have set, look for a gibbous moon paired up with the bright planet Saturn, rising together in the southeast.
Solstice starts—June 21
For the Northern Hemisphere, summer officially begins at 11:54 a.m. ET (15:54 UT) on June 21. During this season, Earth’s northern axis is slightly tilted toward the sun, so that the Northern Hemisphere gets more direct sunlight and experiences warmer temperatures.
By contrast, the June solstice marks the start of winter in the Southern Hemisphere, since locations south of the Equator are tilted away from the sun, making for colder temperatures.
On the first day of the new season and for a few days afterward, the sun will appear to rise at the same place on the horizon, hence the origin of the word “solstice,” meaning “sun stands still” in Latin. From the June solstice onward, the days will start getting shorter in the Northern Hemisphere and longer in the south.
Mercury at its best—June 23
Mercury is usually a challenging planet to spot with the unaided eye because it never strays far from the sun in Earth’s skies, so it appears just before sunrise or for a short time after sunset and is easily lost in the glare of twilight.
But throughout the month of June, Mercury has been pulling away from the sun, climbing higher into the sunset sky. And on the night of the 23rd, it will reach its maximum distance from the sun, as seen by observers, thereby making it easier to hunt down. After today, the little planet will quickly begin to sink back toward the western horizon and will be lost in the glare of the sunset before the end of the month.
Remember to use binoculars if you can to scan the low western sky starting about 20 minutes after sunset, looking for a very faint star-like object to pop into view. It should be easy to spot after that with just the naked eye.
Moon gets a bull’s eye—June 30
You’ll have a second chance this month to see if you can spot the bright star Aldebaran, the “eye” of the constellation Taurus, the bull. This time, however, the crescent moon will act as a convenient guidepost, sitting only three degrees away from the star, a span equal to the width of your three middle fingers held at arm’s length.
You’ll have to be quick to catch this celestial pairing, as Taurus will rise above the eastern horizon within an hour of your local sunrise.