Full Beaver Moon and partial lunar eclipse on November 19, 2021. | SkyNews
Full Beaver Moon and partial lunar eclipse on November 19, 2021 (Chris Vaughan, Starry Night Education)

This Week’s Sky: November 15 to 21, 2021

The highlight of this week is an almost-total lunar eclipse, visible from all over Canada. Also, look for meteors as the Leonids peak.

Monday, November 15 – Mare Imbrium’s golden handle (all night)

Mare Imbrium’s golden handle on November 15, 2021. | SkyNews
Mare Imbrium’s golden handle on November 15, 2021 (Chris Vaughan, Starry Night Education)

On Monday night, November 15, the terminator on the waxing gibbous Moon will fall west of Sinus Iridum, the Bay of Rainbows. The circular 249-kilometre diameter feature is a large impact crater that was flooded by the same basalts that filled the much larger Mare Imbrium to its east, forming a rounded “handle” on the western edge of that mare. The “Golden Handle” effect is produced when sunlight strikes the prominent Montes Jura mountain range surrounding Sinus Iridum on the north and west. Sinus Iridum is almost craterless, but hosts a set of northeast-oriented wrinkle ridges that are revealed at this phase.

Wednesday, November 17 – Bright Moon near Uranus (all night)

Bright Moon near Uranus on November 17, 2021. | SkyNews
Bright Moon near Uranus on November 17, 2021 (Chris Vaughan, Starry Night Education)

In the eastern sky after dusk on Wednesday night, November 17, the very bright, nearly-full Moon will shine two thumb widths to the lower left (or 2.6 degrees to the celestial south) of the magnitude 5.7 planet Uranus. By dawn on Thursday morning, the Moon’s orbital motion will carry it farther from Uranus in the western sky, and the diurnal rotation of the sky will move it to the upper left of the planet. While Uranus’ blue-green dot can normally be seen in binoculars (green circle), I recommend noting its location between the brighter stars of Aries and Cetus, or the nearby star Mu Ceti, and seeking it out a few nights later, when the bright Moon will have moved away.

Thursday, November 18 – Leonid meteor shower peaks (predawn)

Leonids meteor shower peaks on November 18, 2021. | SkyNews
Leonids meteor shower peaks on November 18, 2021 (Chris Vaughan, Starry Night Education)

The Leonids meteor shower, derived from material left by repeated passages of periodic Comet 55P/Tempel-Tuttle, runs from November 3 to December 2 annually. The peak of the shower, when up to 15 meteors per hour are predicted — many with persistent trains — will occur on Thursday, November 18, when Earth will be traversing the densest part of the comet’s debris train. The best viewing time for Leonids will be Thursday morning before dawn, when the radiant in Leo will be high in the eastern sky, but you can watch for occasional Leonids on Wednesday evening, too. The nearly-full Moon at peak will severely reduce the number of meteors seen.

Thursday, November 18 to Friday, November 19 – Full Beaver Moon and partial lunar eclipse

Full Beaver Moon and partial lunar eclipse on November 19, 2021. | SkyNews
Full Beaver Moon and partial lunar eclipse on November 19, 2021 (Chris Vaughan, Starry Night Education)

The November Full Moon, traditionally known as the Beaver Moon or Frost Moon, always shines in or near the stars of Taurus and Aries. The Moon will reach its full phase, directly opposite the Sun in the western pre-dawn sky, at 3:57 a.m. EST or 8:57 GMT on Friday, November 19.

At that time, the Moon will be passing through Earth’s round shadow or umbra, producing the second lunar eclipse of 2021. At maximum eclipse — November 19 at 4:02:56 a.m. EST / 1:02:56 a.m. PST / 9:02:56 GMT — a thin sliver of the Moon’s southern rim will remain outside of the shadow, making this a partial lunar eclipse. The rest of the Moon will darken to a ruddy red colour, especially the Moon’s northern half.

The Moon will first contact the umbra on November 19 at 2:18:41 a.m. EST / 7:18:41 GMT (November 18, 11:18:42 p.m. PST) and will last touch it three hours and 28 minutes later, at 5:47:04 a.m. EST / 2:47:04 a.m. PST / 10:47:04 GMT.

You should notice a slight darkening of the Moon while it traverses the zone encircling the umbra — a penumbral eclipse — before the partial eclipse starts and after it ends.

The entire eclipse will be visible from North America and nearly all of the Pacific Ocean. Eastern Asia, Australia, New Zealand, and Japan will miss the early stages, while South America and western Europe will miss the final stages.

Saturday, November 20 – Watch Algol Brighten (at 6:14 p.m. EST)

Watch Algol brighten on November 20, 2021. | SkyNews
Watch Algol brighten on November 20, 2021 (Chris Vaughan, Starry Night Education)

In the constellation of Perseus, the star Algol, also designated Beta Persei, represents the glowing eye of Medusa from Greek mythology. It is among the most accessible variable stars for skywatchers. During a ten-hour period that repeats every 2 days, 20 hours, and 49 minutes, Algol dims and re-brightens noticeably while a companion star orbiting nearly edge-on to Earth crosses in front of the much brighter main star, reducing the total light output we perceive. Algol normally shines at magnitude 2.1, similar to the nearby star Almach in Andromeda. But when fully dimmed, Algol’s magnitude 3.4 is almost the same as the star Rho Persei (ρ Per), which sits just two finger widths to Algol’s lower right (or 2.25 degrees to the celestial south). On Saturday, November 20 at 6:14 p.m. EST or 23:14 GMT, fully dimmed Algol will sit a third of the way up the east-northeastern sky. Five hours later, the star will shine at full intensity from a perch overhead in the western sky.

Sunday, November 21 – Bright Moon near Messier 35 (all night)

Bright Moon near Messier 35 on November 21, 2021. | SkyNews
Bright Moon near Messier 35 on November 21, 2021 (Chris Vaughan, Starry Night Education)

When the waning gibbous Moon rises among the stars of eastern Taurus after 6 p.m. local time on Sunday, November 21, it will be positioned several finger widths above (or 3 degrees to the celestial west of) the large open star cluster named the Shoe-Buckle Cluster or Messier 35. The Moon and the cluster will share the view in binoculars (green circle) all night long, with the Moon’s orbital motion (green line) halving their separation by dawn. To better see the cluster, which is nearly as wide as the Moon itself, try hiding the Moon just outside the top edge of your binoculars’ field of view.

Monday, November 22 – Mars meets Zubenelgenubi (predawn)

Mars meets Zubenelgenubi on November 22, 2021. | SkyNews
Mars meets Zubenelgenubi on November 22, 2021 (Chris Vaughan, Starry Night Education)

On Monday, November 22, the eastward orbital motion of the planet Mars will carry it only eight arc-minutes (or a quarter of the Moon’s diameter) below the bright and widely separated double star Zubenelgenubi in Libra — close enough to share the view in a backyard telescope (green circle). Look for the trio sitting low in the east-southeastern sky before sunrise, particularly around 6 a.m. local time. They’ll be somewhat higher for observers in the tropics. Mars and the two stars will be telescope-close on Sunday and Tuesday, too — with the small, 3.7 arc-seconds-wide disk of Mars perched above the stars on Sunday and well below them on Tuesday. Mars will shine at twice the brightness of Zubenelgenubi’s primary star. (Note that your telescope may flip and/or invert the view, and that optics must be turned away from the east before the Sun rises.)

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.

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