Third quarter Moon on September 17, 2022 | SkyNews
Third quarter Moon on September 17, 2022 (Chris Vaughan/Starry Night Education)

This Week’s Sky: September 12 to 18, 2022

Our Solar System’s distant gas giants Uranus and Neptune are the stars of the early week.

Every week, SkyNews publishes a list of key events in the Canadian sky in This Week’s Sky. This series gives you all the latest news in Solar System movements, including where the planets are in our sky and Moon phases. From eclipses to meteor showers, This Week’s Sky keeps you updated on the best in upcoming astronomical highlights.

Wednesday, September 14 – The Moon near Uranus (late night)

The Moon near Uranus on September 14, 2022 | SkyNews
The Moon near Uranus on September 14, 2022 (Chris Vaughan/Starry Night Education)

Starting late on Wednesday evening, September 14 in the Americas, the blue-green, magnitude 5.7 speck of Uranus will be positioned several finger widths to the upper right (or 3.9 degrees to the celestial west) of the waning gibbous Moon — close enough for them to share the view in binoculars (green circle). Messier 45, commonly known as the Pleiades cluster will shine off to the Moon’s left. The Moon and Uranus will rise in the east-northeast after 9:30 p.m. local time, and then climb high into the southern sky before dawn. By then the easterly orbital motion of the Moon will shift it farther from Uranus. Hours earlier, observers in much of Northern Africa, Europe, parts of the Middle East, and western Russia can see the Moon occult Uranus around 21:30 UTC — the ninth in a series of consecutive lunar occultations of that planet.

Friday, September 16 – Neptune at opposition (all night)

Neptune at opposition on September 16, 2022 | SkyNews
Neptune at opposition on September 16, 2022 (Chris Vaughan/Starry Night Education)

On Friday, September 16, Neptune will reach opposition. At that time the distant planet will be closest to Earth for this year – a distance of 2.68 billion miles, 4.32 billion km, 4 light-hours, or 28.91 Astronomical Units. Blue Neptune will shine with a slightly brighter magnitude 7.8. Since it’s directly opposite the sun in the sky, Neptune will be visible all night long in backyard telescopes. Good binoculars (green circle) will show it, too, if your sky is very dark. Your best views will come after 9 p.m. local time, when the blue planet has risen higher. Around opposition, Neptune’s apparent disk size will peak at 2.4 arc-seconds and its large Moon Triton will be the most visible (inset). Throughout September, Neptune will be located among the stars of northeastern Aquarius, about a fist’s diameter to the upper right (or 10.5 degrees to the celestial west-southwest) of Jupiter.

Friday, September 16 – Moon meets Mars (overnight)

Moon meets Mars on September 16, 2022 | SkyNews
Moon meets Mars on September 16, 2022 (Chris Vaughan/Starry Night Education)

When the pretty, half-illuminated Moon rises in the eastern sky just before 11 p.m. local time on Friday, September 16, it will be positioned a few finger widths to the left (or 3.5 degrees to the celestial north-northeast) of bright, reddish Mars. They’ll remain cosy enough to share the view in binoculars (green circle) through most of the night while the Moon’s easterly motion pulls it farther from the planet.

Saturday, September 17 – Third quarter Moon (at 21:52 UTC)

Third quarter Moon on September 17, 2022 | SkyNews
Third quarter Moon on September 17, 2022 (Chris Vaughan/Starry Night Education)

The Moon will complete three quarters of its orbit around Earth, measured from the previous new Moon, on Saturday, September 17 at 5:52 p.m. EDT and 2:52 p.m. PDT or 21:52 UTC. At the third (or last) quarter phase the Moon appears half-illuminated, on its western, sunward side. It will rise around midnight local time, and then remain visible until it sets in the western daytime sky in early afternoon. Third quarter moons are positioned ahead of the Earth in our trip around the Sun. About 3.5 hours later, Earth will occupy that same location in space. The week of dark, moonless evening skies that follow this phase are the best ones for observing fainter deep-sky targets.

Sunday, September 18 – Small constellations on high (evening)

Small constellations on high on September 18, 2022 | SkyNews
Small constellations on high on September 18, 2022 (Chris Vaughan/Starry Night Education)

Four very small constellations sit high the southern evening sky, near the southeastern edge of the Summer Triangle, on September evenings. The easiest one to see is Delphinus, the Dolphin. It is composed of four medium-bright stars forming a small elongated diamond connecting to a straight tail star that extends to the lower right (or celestial southwest). Equuleus, the Little Horse sits about a fist’s diameter below Delphinus. Diminutive Equuleus is the second to last constellation, by size after Crux, the Southern Cross. Sitting a generous fist’s width to Delphinus’ upper right is the next smallest constellation Sagitta, the Arrow. And sweeping a palm’s width farther in the same direction will bring you to the bent-stick stars of Vulpecula, the Fox. Except for the slightly larger fox, each of these small constellations will fit within the field of view of binoculars (green circle). The Milky Way passes through Sagitta and Vulpecula, populating them with a variety of deep sky objects. Look between those two constellations for a dark dust lane.

Chris Vaughan is a science writer, geophysicist, astronomer, planetary scientist and an “outreach RASCal.” He writes Astronomy Skylights, and you can follow him on Twitter at @astrogeoguy. He can also bring his Digital Starlab portable inflatable planetarium to your school or other daytime or evening event. Contact him through to tour the Universe together.