Comet C/2022 E3 (ZTF) closest to Earth on February 1, 2023, at 9 p.m. (Chris Vaughan) | SkyNews
Comet C/2022 E3 (ZTF) closest to Earth on February 1, 2023, at 9 p.m. (Chris Vaughan)

This Week’s Sky: January 30-February 5

The long-period comet designated C/2022 E3 (ZTF) is predicted to become bright enough to be seen by Northern Hemisphere skywatchers on February 1.

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.

Monday, January 30 – Mercury at greatest western elongation (before sunrise)

Mercury at greatest western elongation on January 30, 2023, at 6:30 a.m. (Chris Vaughan) | SkyNews
Mercury at greatest western elongation on January 30, 2023, at 6:30 a.m. (Chris Vaughan)

On Monday, January 30, Mercury (orbit shown in red) will reach its widest separation of 25 degrees west of the Sun, and maximum visibility for its current morning apparition. With Mercury positioned close to the tilted morning ecliptic (green line) in the southeastern sky, this appearance of the planet will be a relatively good one for both Northern and Southern Hemisphere observers. The optimal viewing times at mid-northern latitudes will start around 6:15 a.m. local time. Viewed in a telescope (inset) the planet will exhibit a waxing, slightly gibbous phase, and the medium-bright star Omicron Sagittarii will shine nearby. 

Monday, January 30 – Bright Moon versus Mars (overnight)

Bright Moon versus Mars on January 30, 2023, at midnight. (Chris Vaughan) | SkyNews
Bright Moon versus Mars on January 30, 2023, at midnight. (Chris Vaughan)

On Monday night, January 30, the waxing gibbous Moon will once again shine close enough to the bright reddish dot of Mars for them to share the view in a backyard telescope (green circle). 

After dusk in the Americas, look high in the southern sky to see the Moon positioned a short distance to Mars’ right (or celestial southwest). Through the night, the Moon’s eastward orbital motion will carry it closely past the red planet while the diurnal rotation of the sky alters the angle between them. 

Observers located in the southern United States, Mexico, Central America, and northern South America can see the Moon occult Mars around 06:00 GMT on January 31. Use an app like Starry Night to determine the start and end times where you live. 

Wednesday, February 1 – Comet C/2022 E3 (ZTF) closest to Earth (all night)

Comet C/2022 E3 (ZTF) closest to Earth on February 1, 2023, at 9 p.m. (Chris Vaughan) | SkyNews
Comet C/2022 E3 (ZTF) closest to Earth on February 1, 2023, at 9 p.m. (Chris Vaughan)

The long-period comet designated C/2022 E3 (ZTF) is predicted to become bright enough to be seen by Northern Hemisphere skywatchers using binoculars and even their unaided eyes when it passes closest to Earth on Wednesday, February 1. 

The closest approach of 26.5 million miles (42.7 million km), about 110 times farther than the Moon, will occur around 18:00 GMT. That translates to mid-day in the Americas. The best viewing time there for the comet will be mid-evening on Wednesday, when the comet will be highest in the northern sky and about two fist diameters above (or 19.5 degrees to the celestial south-southwest of) Polaris. The surrounding nights should be almost as good for viewing, although the Moon will be waxing fuller each evening. 

After perigee, the comet will travel higher in the evening sky towards the bright star Capella until February 5, and then pass close to Mars on February 10 (red path with labelled dates:time). An app like Starry Night will show its nightly location where you live. 

Thursday, February 2 – Moon crosses the Winter Heptagon (evening)

Moon crosses the Winter Heptagon on February 2, 2023, at 7 p.m. (Chris Vaughan) | SkyNews
Moon crosses the Winter Heptagon on February 2, 2023, at 7 p.m. (Chris Vaughan)

The Winter Football, also known as the Winter Hexagon and Winter Circle, is an asterism composed of the brightest stars in the constellations of Canis Major, Orion, Taurus, Auriga, Gemini, and Canis Minor — specifically Sirius, Rigel, Aldebaran, Capella, Castor and Pollux, and Procyon. 

The hexagon is visible during evenings from mid-November to spring every year. This year though, the red planet Mars’ position in Taurus between Aldebaran and Capella has turned it into the Winter Heptagon! 

Viewed during the evening from mid-Northern latitudes, the huge pattern will stand upright in the southern sky. It stretches from about 30 degrees above the horizon to overhead. The Milky Way passes vertically through the asterism, but you will not see its faint glow while the waxing gibbous Moon journeys through the giant shape from Tuesday to Thursday this week (red path with dates:hour). 

Friday, February 3 – Bright Moon aligns with Gemini’s Twins (all night)

Bright Moon aligns with Gemini’s Twins on February 3, 2023, at 6:30 p.m. (Chris Vaughan) | SkyNews
Bright Moon aligns with Gemini’s Twins on February 3, 2023, at 6:30 p.m. (Chris Vaughan)

In the eastern sky on Friday evening, February 3, the bright Moon will shine several finger widths below (or three degrees to the celestial southeast) of the bright star Pollux in Gemini. The other slightly fainter twin, the star Castor, will sparkle above them, forming a nearly straight line. As the trio crosses the sky during the night, the eastward orbital motion of the Moon will carry it farther from Pollux while the diurnal rotation of the sky rotates Gemini’s stars to the Moon’s right. 

Saturday, February 4 – Blue Mare Tranquillitatis (all night)

Blue Mare Tranquillitatis on February 4, 2023, at 9 p.m. (Chris Vaughan) | SkyNews
Blue Mare Tranquillitatis on February 4, 2023, at 9 p.m. (Chris Vaughan)

The maria, Latin for “seas,” are the large, dark regions visible on the Moon’s near side. They are basins excavated by major impactors early in the Moon’s geologic history and later infilled with dark basaltic rock that upwelled from the interior of the Moon. Several maria link together to form a curving chain across the northern half of the Moon’s near-side. Mare Tranquillitatis, where humankind first walked upon the Moon, is the large, round mare in the centre of the chain. Sharp-eyes might detect that this mare is darker and bluer than the others, due to enrichment in the mineral titanium. 

Sunday, February 5 – Mini full Snow Moon (at 18:28 GMT)

Mini full Snow Moon on February 5, 2023, at 18:28 GMT. (Chris Vaughan) | SkyNews
Mini full Snow Moon on February 5, 2023, at 18:28 GMT. (Chris Vaughan)

The February full Moon will occur on Sunday, February 5 at 1:28 p.m. EST, 10:28 a.m. PST, or 18:28 GMT. 

The indigenous Anishnaabe (Ojibwe and Chippewa) people of the Great Lakes region call the February full moon Namebini-giizis “Sucker Fish Moon” or Mikwa-giizis, the “Bear Moon”. For them it signifies a time to discover how to see beyond reality and to communicate through energy rather than sound. 

The Algonquin call it Wapicuummilcum, the “Ice in River is Gone” Moon. The Cree of North America call it Kisipisim, the “the Great Moon” — a time when the animals remain hidden away and traps are empty. For Europeans, it is known as the Snow Moon or Hunger Moon. 

Since it’s opposite the Sun on this day of the lunar month, the Moon will be fully illuminated, and rise at sunset and set at sunrise. February full Moons culminate very high in the night sky and cast shadows similar to the summer midday Sun. Because this Moon will be full only 33 hours after the Moon’s apogee (its greatest distance from Earth this month) it will look about five per cent smaller than average (red circle). This means it will be the opposite of a supermoon and the smallest full Moon of 2023. 

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 AstroGeo.ca to tour the Universe together.