The Night Sky This Month: November 2021

Godzilla Galaxy
Image credit: NASA, ESA, HST, and Judy Schmidt

With a diameter of 800,000 light-years, this spiral galaxy, designated UGC 2885, is eight times bigger than the Milky Way, which places it among the biggest spiral galaxies we know to exist. However, this galaxy’s real claim to fame is the fact that its rotation curve proved the existence of Dark Matter.

Also known as the “Godzilla Galaxy, or perhaps more elegantly, as Rubin’s Galaxy, this galaxy is located about 232 million light-years away, and it was the prime focus of a study by astronomer Vera Rubin to map the rotation curves of large galaxies. In theory, the outer parts of a large galaxy should revolve around a galaxy’s core at a slower speed than the inner regions should, but what Rubin found in practice was that, except for the very core of the galaxy, all parts of the galaxy rotated at the same speed.

This finding was repeated with about 60 or so other large spiral galaxies, which later came to prove the existence of Dark Matter, the existence of which was first postulated by Jan Oort and Fritz Zwicky in 1932 and 1933. While nothing is known about the nature of Dark Matter, it is thought that galaxies are “embedded” in rotating masses of Dark Matter, which explains why all parts of galaxies rotate at the same rate.

While Vera Rubin never received the Nobel Prize for her groundbreaking work, her discovery was recognized when the Large Synoptic Survey telescope was renamed the Vera C. Rubin Observatory in her honor.

The Moon Phases in 2021

New Moon First Quarter Full Moon Third Quarter
November 4th November 11th November 19th November 27th

The Planets in 2021

Mercury will be visible before dawn low on the east-southeastern horizon for the first week or so of the month. On 1 November, the little planet will shine at about magnitude -0.84, but note that it will begin to sink toward the horizon as the Sun rises, so take extreme care when using binoculars to view the planet.

Venus starts the month shining at magnitude -4.57, but sadly, because the ecliptic is at a very shallow angle with respect to the horizon, the planet will remain within about 10 degrees above the south-southwestern horizon for the remainder of the year. As a result, it might be difficult to spot Venus low on the horizon just before darkness falls.

Mars has just emerged from behind the Sun and will become visible in the east-southeast before dawn shining at magnitude 1.65. By month’s end, the Red planet will be best placed at about 07:00 (GMT), but take extreme care not to view the planet with binoculars after the Sun has risen.

Jupiter starts the month of November shining at magnitude -2.49 in the south when it transits the meridian at an elevation of about 22 degrees. By month’s end, the ‘King of the Planets’ will transit the meridian at about 17:20 (GMT), at which time it will have an angular diameter of 38.27 seconds of arc and shine at magnitude -2.29. Sadly, even though the planet is steadily gaining altitude as it climbs up the ecliptic, it will remain within about 25 degrees above the horizon for the remainder of 2021.

Saturn rises shortly before Jupiter, and it will cross the meridian at about 18:00 (GMT) at the start of the month. Moreover, like Jupiter, Saturn will remain at about 20 degrees above the southern horizon for the remainder of 2021, meaning that it could be challenging to obtain clear views of the ring system that is still tilted towards our line of sight.

Meteor Showers in 2021

The month of November sees two meteor showers, these being-

– The Taurids Meteor Shower, which is expected to peak on the night of the 4th/5th of the month. Although the Taurids is a long-running shower that consists of two distinctly separate streams, neither stream is known for delivering more than about 5 to 10 or so meteors per hour during the peak period. Nonetheless, this year there will be no moonlight to interfere, so it might be possible to observe almost all the bright meteors during the peak period just after midnight.

– The Leonids Meteor Shower is an average shower that rarely produces more than about 15 or so meteors per hour during its peak, which is expected to occur on the night of the 17th/18th of November. This shower is the result of debris left behind by the comet Tempel-Tuttle, but once every 33 years, the earth passes through a particularly dense debris trail, causing the cyclonic outbursts this shower is best known for. Sadly, though, this year the shower occurs close to the Full Moon, which will extinguish all but the brightest meteors. Note that while the shower’s radiant is in the constellation Leo, Leonids can appear from almost any point in the sky.

Deep Sky Objects to Look for in 2021

Prominent constellations in the south at this of the year include Aquila, Cygnus, Lyra, Perseus, Taurus, and Cassiopeia, all of which contain a large variety of spectacular objects that are easy targets for modest amateur observing equipment. Below are some details of a few such objects in the constellations Cygnus:

Messier 29 (M29, NGC 6913)

Located about 4,000 light-years away, this pretty open cluster has an apparent visual magnitude of 8.59 and is an easy target even for modest binoculars about 1.7 degrees to the south-eastward of the star Gamma Cygni. As open clusters go, M39 is rather young, since it is estimated to be no only about 10 million years (or so) old.

Messier 39 (M39, NGC 7092)

By way of contrast, M39 is estimated to be between about 200 million and about 300 million years old, which is an intermediate age for open clusters. However, unlike many open clusters, all the confirmed members of M39 are still on the main sequence, and all the brightest members are expected to evolve into red giants at about the same time. Look for this pretty magnitude 5.5 open cluster about 2.5 degrees to the westward, and about one degree to the southward of the bright star Pi-2 Cygni.

Crescent Nebula (NGC 6888, Caldwell 27, Sharpless 105)

Located about 5,000 light-years away, this spectacularly beautiful and complex nebula spans across 26 light-years, and it was created when the progenitor star, a so-called Wolf Rayet star, had evolved into a red giant star about 400,000 years ago. However, in this case, the complexity of the bubble of gas is the result of gas and stellar material being blown off by the red giant colliding with material the very hot, old, and massive progenitor star had blown off earlier while it was still on the main sequence.

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