Each Monday I pick out the northern hemisphere’s celestial highlights (mid-northern latitudes) for the week ahead, but be sure to check my main feed for more in-depth articles on stargazing, astronomy, eclipses and more.
The Night Sky This Week: July 31-August 6, 2023
This year there are 12 months, but 13 full moons. It’s a product of a lunar year being 354 days while a solar year being 365.24 days. That means one month of the year must have two full moons—and that’s August 2023—but it gets even better. Not only is this week’s full “Sturgeon Moon” joined on August 31 by a full “Blue Moon,” but both are 2023’s closest full moons—“supermoons”! As such they will appear just slightly larger and a bit brighter than average, though it’s hard to tell the difference.
Tuesday, August 1: A ‘Supermoon’ And ‘Lammas’
The second full Moon of summer in the northern hemisphere, the “Sturgeon Moon” is a supermoon, turning full while 357,311 km from Earth. That’s only slightly farther away than next month’s closest full Moon, so the “Sturgeon Moon” will be very big and very bright. It will look its best at moonrise on two successive evenings, Monday, July 31 and Tuesday, August 1.
Today is also Lammas, a traditional pagan celebration of the first harvest of the season. The date is astronomically significant because today is a cross-quarter day—the halfway point between June’s solstice and September’s equinox.
Thursday, August 3: Moon And Saturn
Rising in the east-southeast in darkness tonight will be a 96%-lit waning gibbous moon. Look just to the left of it and you’ll see ringed planet Saturn. It’s the ideal time to train a telescope on two of the night sky’s most beautiful objects.
Constellation Of The Week: Ophiuchus
The summer constellation of Ophiuchus is known as the 13th constellation. Despite it being a very large constellation on the ecliptic—so therefore hosting the Sun just like Leo, Taurus and all the others—it was the victim of ancient Babylonians aversion of the number 13 (a superstition that continues even now). It’s therefore little-known and ts bright stars rather lost to all but committed stargazers.
Find the bright star Rasalhague at the top of Ophiuchus then go to the right to find Rasalgethi at the foot of Hercules. Just below Rasalgethi is where you’d see NASA’s ancient Voyager 1 space probe … if you had terrific eyesight (it’s only the size of a small car). Ophiuchus is also where in 2021 astronomers found 70 rogue Jupiter-type planets. The sun hangs out in front of Ophiuchus from late November through December 18 every year.
Object Of The Week: Supermoons
This week sees the rise of 2023’s second “supermoon.” They occur because the moon’s orbit of Earth is slightly elliptical, so in every 29.5 day orbit there is a point when it is closest to Earth and therefore appears slightly largest in our sky (perigee) and a point when its farthest, so looks smaller (apogee).
Perigee and apogee happen every month 14 days apart, but only rarely do they coincide with the phases of the Moon we notice most easily—the full moon. The closest perigee full moons of any given year tend to be called supermoons. There are four in 2023—July 3, August 2, August 31 and September 29.
Times and dates given apply to mid-northern latitudes. For the most accurate location-specific information consult online planetariums like Stellarium and The Sky Live. Check planet-rise/planet-set, sunrise/sunset and moonrise/moonset times for where you are.
Wishing you clear skies and wide eyes.