For July 2023, The Moon is Full, the Thunder Moon, is on July 3rd. The Earth is at aphelion, farthest from the Sun, on July 6, meaning the sun appears smallest and dimmest in our sky then. Obviously the fact that we in the northern hemisphere are tilted most toward it in summer makes a far bigger difference in our seasons, for this distance variation is only about 1%; our orbit is almost circular. The waning gibbous moon passes south of Saturn on July 7th. The last quarter moon is on July 9th, and the waning crescent passes Jupiter on July 11th. The new moon is on July 17th. The very slender waxing crescent lies just to the right of Mercury low in the west 45 minutes after sunset on July 18th, is just north of the triangle of the Venus, Regulus, and Mars on July 19 and above the trio on July 20th, just right of Mars.

Planets in Greek means "the wanderers". Never more than this month’s evening sky, as the complex motions of inferior Venus retrograding contrasts with superior Mars in direct motion. For the last two months, faster moving Venus has been overtaking more distant Mars in the western sky night by night, but she never catches him! Instead she has reached the edge of her orbit, half lit in the telescope, and for July, appears as a larger but slimmer crescent each evening, heading back west to pass between us and the Sun in August. She will spend the last four months of 2023 in the dawn sky. As July begins, Mars lies midway between brilliant Venus (so bright it is visible in daylight now!) and Regulus in Leo. Mars passes just above Regulus on July 9th, and Venus comes close, but never reaches Regulus, passing south of it on July 19th. To make it more interesting, Mercury comes out from behind the Sun in late July, passing just north of Venus on July 24th, and appearing to merge naked eye with Regulus on July 28th. Use binoculars to resolve them, with Venus just below them. Quite a end to a busy month!

Things much more placid in the dawn sky, with Saturn rising about 11 p.m. in Aquarius, and Jupiter about 3 a.m. in Aries. Both will return to the evening sky by fall. I observed Saturn last week, and it is notable just how much the rings have flattened since last year. They will be at equinox, facing the Sun and earth edge on, in May 2025, and appear so thin as to vanish for several weeks in most earth based telescopes!

High overhead is the Big Dipper, and its handle will be the guide to the biggest news in cosmology in 2023. Just north of the end of the handle is M-101, the "Pinwheel Galaxy", one of the most photogenic spirals and best known galaxies in the whole sky, visible even with big binoculars. In one of its spiral arms, Japanese amateur Koichi Itagak, noted a 15th magnitude supernova on May 19, 2023. It rose in brightness by about 100X in the next week, peaking at about 10th magnitude in late May, and has faded very slowly, still about 11.5 as of this writing.

Note the supernova for the time being is rivaling the light output of all the other hundreds of billions of stars in this spiral galaxy, even bigger and more massive than the Milky Way! If it were within a thousand light years of us, it would be easily seen in broad daylight!

If you drop south from the bowl of the Big Dipper, Leo the Lion is in the SW. Note the Egyptian Sphinx is based on the shape of this Lion in the sky. Note the brightest star of Leo, Regulus, gets a very close visit from Mercury on July 28th!

Taking the arc in the Dipper’s handle, we "arc" SE to bright orange Arcturus, the brightest star of Spring. Cooler than our yellow Sun, and much poorer in heavy elements, some believe its strange motion reveals it to be an invading star from another smaller galaxy. This is the Sagittarius Dwarf Galaxy, now colliding with the Milky Way in Sagittarius in the summer sky. It lies on the far edge of our own barred spiral, and may account for the formation of our bar. Moving almost perpendicular to the plane of our Milky Way, Arcturus was the first star in the sky where its proper motion across the historic sky was noted, by Edmund Halley.

Spike south to Spica, the hot blue star in Virgo, then curve to Corvus the Crow, a four sided grouping. North of Corvus, in the arms of Virgo, is where our large scopes will show members of the Virgo Supercluster, a swarm of over a thousand galaxies about 50 million light years distant.

To the east, Hercules is well up, with the nice globular cluster M-13 marked on your sky map and visible in binocs. The brightest star of the northern hemisphere, Vega rises in the NE as twilight deepens. Twice as hot as our Sun, it appears blue-white, like most bright stars.

Northeast of Lyra is Cygnus, the Swan, flying down the Milky Way. Its bright star Deneb, at the top of the "northern cross" is one of the luminaries of the Galaxy, about 50,000 times more luminous than our Sun and around 3,000 light years distant. of the Galaxy, and a little above (north) of Vega.

South of Deneb, on a dark clear night, note the "Great Rift", a dark nebula in front of our solar system as we revolve around the core of the Milky Way in the Galactic Year of 250 million of our own years. The star at the south end of the Northern Cross is one of my favorites, Albireo, the "gator star", a notable orange and blue double at 20X.

As we head south, Antares is well up at sunset in Scorpius. It appears reddish because it is half as hot as our yellow Sun; it is bright because it is a bloated red supergiant, big enough to swallow up our solar system all the way out to Saturn’s orbit! Scorpius is the brightest constellation in the sky, with 13 stars brighter than the pole star Polaris! Note the fine naked eye clusters M-6 and M-7, just to the left of the Scorpion’s tail.

Just a little east of the Scorpion’s tail is the teapot shape of Sagittarius, which lies toward the center of the Milky Way. From a dark sky site, you can pick out the fine stellar nursery, M-8, the Lagoon Nebula, like a cloud of steam coming out of the teapot’s spout. This view of our home galaxy stretching overhead is for about midnight on July evenings, looking from the South to overhead.

Of course, you will need dark skies to see this kind of beauty, but many have plans for trips to parks and out west this summer, so be sure to plan for at least a few evenings under dark skies to appreciate our galaxy.