The Full Strawberry Moon, Summer Starts, Mercury and Mars Smooch, and a Look at Ophiuchus!
The Solstice starts the Northern Summer
The beginning of summer for the Northern Hemisphere, known as the Summer Solstice, occurs on Friday, June 21 at 11:54 am Eastern Daylight Time. At that moment, the northern end of Earth’s axis of rotation will be tilted 23.5° towards the sun. As a result, the Sun will reach its highest noonday position in our sky for the year. Sunlight will shine more intensely on the Northern Hemisphere, and deliver our longest amount of daylight. More hours of concentrated, direct sunlight translates to more solar energy and warmer days! It is NOT the case, as some people think, that we are warmer because we are closer to the Sun — that event, called perihelion, actually happens in early January every year! As a matter of fact, the Earth is only two weeks away from reaching its widest separation from the sun, or aphelion for this year. That occurs on July 4.
For our friends in the southern hemisphere, this solstice signals the sun’s lowest noon-time height for the year, and marks the start of their winter. The summer solstice is good news for astronomers — after Friday, the days will slowly start to get shorter while the nights lengthen.
The Moon and Planets
The June full moon will light up our skies worldwide to open the week — then it will pass the baton back to Jupiter, the father of the planets. (See what I did there?) Here are the Skylights!
Tonight (Sunday), the moon will land to Jupiter’s lower left. Notice the relative positions of those two objects while they are over the eastern horizon, and compare that to the way they look hours later. The moon will move steadily farther from Jupiter through the night. And, because Earth’s rotation causes constellations and planets to flip by 180 degrees as they cross the sky from east to west, the moon will end the night higher than Jupiter.
The June full moon, colloquially known as the Strawberry Moon, Mead Moon, Rose Moon, or Hot Moon, always shines in or near the stars of southern Ophiuchus (the Serpent-Bearer). The indigenous Ojibwe of the Great Lakes region call this moon Ode’miin Giizis, the Strawberry Moon. (Next month’s will be the Raspberry Moon.) The Cree Nation of central Canada calls the June full moon Opiniyawiwipisim, the Egg Laying Moon (referring to wild water-fowl habits). The Mohawks call it Ohiarí:Ha, the Fruits are Small Moon.
Because the moon reaches its full phase when it is opposite the sun in the sky, full moons always rise in the east as the sun is setting, and set in the west at sunrise. Since sunlight is hitting the moon vertically at that time, no shadows are cast by terrain on the full moon; all of the variations in brightness we see from Earth are generated by differences in the reflectivity, or albedo, of the lunar surface rocks.
The moon will be completely full in the wee hours of Monday morning, so the moon will look full at a glance on both Sunday and Monday evening. Binoculars and telescopes will show you a thin strip of darkened terrain along the moon’s left (its western) limb on Sunday evening, and along its right (eastern) limb on Monday evening. Try it!
When the bright, now waning gibbous moon rises over the southeastern horizon at 10:30 pm local time on Tuesday evening, the bright, yellowish planet Saturn will be positioned only one finger’s width above it. If you note where Saturn is, you can find it again later in the week, once the moon has departed. Since the two objects will be so close together in the sky, the continuous eastward slide of the moon during the night will be more pronounced.
The moon and Saturn will cross the sky together during the night and will easily fit within the field of binoculars or a backyard telescope at medium magnification. Lucky observers in Easter Island, southern South America, the Antarctic Peninsula, and southern Africa will see the moon pass in front of, or occult, Saturn.
For the rest of the week, the moon will continue to wane in phase and rise later, passing through the dim constellation of Capricornus (the Sea-Goat) and then Aquarius (the Water-Bearer) to end the week. Watch for the late-rising moon to linger into the morning daytime sky this weekend.
After last week’s opposition Jupiter will still be rising around sunset this week, and will remain a fantastic sight all night long — blazing brightly in the southern half of the sky. From time to time, the small, round black shadows cast by Jupiter’s four Galilean moons become visible in amateur telescopes as they cross (or transit) Jupiter’s disk. Starting just after midnight on Tuesday evening, Io and its shadow will cross Jupiter for more than two hours. Io itself will be tough to see, but it will sit very close to its shadow. On Friday, Europa and its shadow will cross Jupiter for two hours, with the Great Red Spot, starting after midnight (i.e., Saturday morning).
Due to Jupiter’s rapid 10-hour rotation period, the Great Red Spot (or GRS) is only observable from Earth every 2nd or 3rd night, and only during a predictable three-hour window. The GRS will be easiest to see using a medium-sized, or larger, aperture telescope on an evening of good seeing (steady air). If you’d like to see the Great Red Spot in your telescope, it will be crossing the planet on Monday evening until 12:20 am EDT. More GRS viewing opportunities will occur on Wednesday after 10:30 pm EDT and from 8 to 11 pm EDT on Saturday.
Yellowish Saturn will be rising in the east-southeast after 10 pm local time this week. Its position in the sky is just to the left (east) of the stars that form the teapot-shaped constellation of Sagittarius (the Archer). Saturn is quite a bit dimmer than Jupiter. To find it, look about 2.5 fist diameters to the lower left (east) of Jupiter. Dust off your telescope — because even a small one will show its rings and several of its brighter moons! Once it’s dark, a small telescope should be able to reveal some of the ringed planet’s larger moons, especially Titan. Because Saturn’s axis of rotation is tipped about 27° from vertical (a bit more than Earth’s is), we can see the top surface of its rings, and its moons can appear above, below, or to either side of the planet. During this week, Titan will migrate counter-clockwise around Saturn, moving from the lower left tonight to the upper right next Sunday. (Remember that your telescope will flip the view around.)
Mars and Mercury are hanging out just above the northwestern horizon after sunset this week. Mercury will become easier to spot every night while it climbs away from the sun and brightens. The best time to look for Mercury falls between 9:45 and 10:30 pm local time. Next Sunday, June 23, Mercury will peak in visibility when it reaches its widest separation, 25 degrees east of the Sun, for the current apparition.
Mercury’s recent orbital motion is carrying it directly towards, and then above, dimmer Mars. Tonight, Mars will be positioned about a finger’s width to the left of Mercury. From Monday to Wednesday, the two planets will “kiss”! Closest approach will occur on Tuesday. (Take care that the sun has set before attempting to view them using binoculars or a telescope.)
Distant and dim, blue Neptune is in the southeastern pre-dawn sky, among the stars of Aquarius (the Water-Bearer). The planet will be rising after 1 am local time this week. On Friday, Earth’s faster orbit will cause Neptune to cease its regular eastward orbital motion in front of the background stars and begin a retrograde loop that will last until late November. For now, you’ll find the magnitude 7.9 planet sitting a thumb’s widths to the left (east) of a medium-brightness star named Phi (φ) Aquarii.
To round out the planet inventory for the week, blue-green Uranus will be rising just before 3 am local time, and is sitting among the stars of Aries (the Ram). Venus is sitting low in the east-northeastern pre-dawn sky, sinking ever-closer to the rising sun. Venus will be rising at about 4:40 am local time.
Oh, Look — it’s Ophiuchus!
By the end of this week, the moon will be vacating the evening sky worldwide, leaving it nice and dark for our sky-watching.
The twelve constellations of the Zodiac are only special because the great circle of the Ecliptic carries the sun through each of them in turn. The Sun spends varying amounts of time in each constellation, and those dates repeat every year. For example, in the present era, the sun traverses the constellation of Gemini (the Twins) from June 21 to July 19 every year. Remember, the sun isn’t moving — it’s Earth’s motion around the sun that makes it appear to change location compared to the fixed distant background stars.
If you’re an astrology enthusiast, you’ll be wondering by now why is the sun traversing Gemini in June and July when the Gemini “star sign” is for birthdays from May 22 to June 21? There’s a simple reason for it. Thousands of years ago, when astrology was formulated by the Greeks and Babylonians, the sun traversed Gemini during that part of the year. It’s one of many reasons why most astronomers place no value in astrology, whatsoever. By the way — if you have an astronomy app or program that allows the year to be changed, you can prove this for yourself by setting the app to noon, centring on the sun, and then changing the date to June 25th, 16 AD. The sun will hop into Cancer (the Crab), which sits east of Gemini!
Most of the Zodiac constellations are inconspicuous — if not nearly invisible in urban skies. Aries (the Ram) has two decently bright stars that form a little stick, while Cancer, Pisces (the Fishes), Aquarius (the Water Bearer), and Capricornus (the Goat) are seriously tough to make out — unless you travel to dark skies. A few of them, Gemini (the Twins), Taurus (the Bull), Scorpius (the Scorpion), and Leo (the Lion), have very bright stars that form easily recognizable shapes. The rest of them fall in the medium-bright range.
All of the major objects in our Solar System remain near the Ecliptic/Zodiac. This year, Jupiter is sitting in the “thirteenth zodiac constellation”, and June is a prime month to observe it. Ophiuchus (“Oh-phee-YOU-cuss”), the Serpent Bearer is a huge constellation (11th largest by area) that sits above and between the Teapot asterism of Sagittarius (the Archer) and Scorpius, and below Lyra (the Lyre) and Hercules. The Ecliptic crosses the southernmost (lower) stars of Ophiuchus, but it has never been considered part of the zodiac because that would exceed the special system of 12 sky divisions important to ancient astrologers.
In China, Ophiuchus is considered part of 天市左垣(Tiān Shì Zuǒ Yuán), Left Wall of the Heavenly Market Enclosure. Ophiuchus’ stars are only moderate in brightness, so it’s another constellation that is better to look for when the sky is darker. The constellation’s shape resembles a large, upright box (26° tall and 16° wide) with a pointed triangle on the upper edge. (Think of a Dalek from Doctor Who, but without the plunger.) The constellation’s brightest star, Rasalhague “the head of the serpent charmer”, marks the peak of the triangle. The star sits below, and about midway between, very bright star Vega and Antares. The latter is the reddish star that is sitting a fist’s diameter to the right of Jupiter this summer.
Immediately east and west of the main body of the Serpent-Bearer are two long sections of a separate, split-in-two constellation, Serpens — the Serpent that Ophiuchus is carrying. The western (right) half is called Serpens Caput (the Snake’s Head), and the eastern (left) portion is Serpens Cauda (the Snake’s Tail).
From east to west (left to right in the Northern Hemisphere), the stars forming the bottom of the box are: medium bright Sabik “the preceding one”, dimmer Zeta Ophiuchi, and two dimmer stars a finger width apart named Yed Prior “leading hand” and Yed Posterior “trailing hand” which mark the western hand. About a palm’s diameter to the upper left of the two Yeds is Marfik “the elbow”. Sabik is the star that Uranus’ northern axis of rotation points towards (like our own pole star, Polaris)!
You’ll need an astronomy app and a small telescope to see it, but Ophiuchus is home to Barnard’s Star — a red dwarf six light-years away. It is the fourth closest known star, and the closest observable from the northern hemisphere. Barnard’s Star sits 3.5 finger widths to the east (left) of Celebrai, Ophiuchus’ eastern shoulder star. Being so close, we can actually watch Barnard’s Star travel through the galaxy in a process known as proper motion. It moves about half the Moon’s diameter in a human lifetime.
Because Ophiuchus sits just above the plane of the Milky Way, it is chock full of Globular Clusters — spherical, tightly packed groups of stars that orbit our galaxy tens of thousands of light-years away from us. A large, reasonably bright one designated Messier 10 sits just about where the Serpent-Bearer’s belt buckle would be. You can see these clusters in binoculars or a small telescope, especially from a dark sky site.
The south-eastern (or bottom) part of the constellation dips into the Milky Way. By midnight, the centre of Ophiuchus is due south — right above Jupiter and about halfway up the sky. Let me know if you check it out!
Keep looking up, and enjoy the sky when you do. I love questions and requests — so, send me some!