By Robert Victor and Robert D. Miller

These star maps, Sky Calendars, and monthly summaries of sky events for October 2020 through January 2021 are intended to help teachers guide students to embark on following the seasonal progression of the stars; to notice changes in the arrangements of Moon, planets, and stars in the sky; and, together, over time, tap into the dynamic yet serene beauty of the sky.

Rachel Carson wrote eloquently in The Sense of Wonder, a wonderful little book about sharing nature with children:

"Those who dwell, as scientists or laymen, among the beauties and mysteries of the earth are never alone or weary of life. Whatever the vexations or concerns of their personal lives, their thoughts can find paths that lead to inner contentment and to renewed excitement in living. Those who contemplate the beauty of the earth find reserves of strength that will endure as long as life lasts.

"The lasting pleasures of contact with the natural world are not reserved for scientists but are available to anyone who will place himself under the influence of earth, sea and sky, and their amazing life."

Jupiter and Saturn appear near each other in the early evening for the rest of 2020 (and not again until 2040), and in December will have their closest pairing since 1623. (After December 2020, students will have to wait until 2080 to see these giant planets as closely paired again.) Evenings in October 2020, Mars is closer and brighter than it will be again until 2035. The sky frequently offers pairings of the Moon with the five planets whose brightness and motions have attracted attention since ancient times; pairings and groupings of planets; and pairings of Moon and planets with the five stars of first magnitude within the well-known belt of zodiac constellations.

Sky maps for twilight -- introduction

Illustrated monthly calendars of sky events with evening constellation charts

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Sky events in October 2020

For details, see the October section in the August-September issue of California Classroom Science. Here’s a brief summary for the rest of October.

Seasonal stars, at dusk (see evening twilight chart for October, above): Summer Triangle of Vega, Altair, Deneb passing overhead; Arcturus sinking low in W to WSW; Antares sinking low in SW; Fomalhaut climbing from low in SE.

Seasonal stars, at dawn (see morning twilight chart for October, above): The Dog Star, Sirius, crossing through south as the month progresses, is the brightest night time star, but is far less bright than Venus in E and Mars in W. Orion’s belt (not shown), between Rigel and Betelgeuse, points in one direction toward Sirius, and in the opposite direction toward Aldebaran, eye of Taurus, and beyond to the beautiful Pleiades star cluster (not shown). Look earlier in morning, in darker skies, for this cluster. Procyon in Canis Minor completes the almost equilateral Winter Triangle with Sirius and Betelgeuse. Look for the “Twin” stars, Pollux and Castor, 4.5° apart in Gemini, and Capella, northern tip of the huge Winter Hexagon comprised of all the aforementioned  stars, except for Betelgeuse inside. Regulus, heart of Leo, chases the Winter Hexagon across the sky. Late in October, watch for Arcturus rising in ENE. On the last day or two of the month, binoculars show Spica low in ESE, just emerging from the Sun’s glare. By early November, brightening Mercury will appear nearby.

Planets: Mars in October reaches its closest approach to Earth and greatest brilliance until 2035. Mars reaches opposition on October 13, as Earth overtakes the red planet. Mars is visible in nearly all of October’s nighttime hours: Low in east at dusk, high in south in middle of night, and low in west at dawn.

Jupiter and Saturn are close together in south at dusk, moving into SSW as the month progresses. They’re separated by 7° on October 7; by 6° on October 21, and by just 5° on November 2. For illustrations, see Sky Calendars for October and November, above. The best is yet to come!

Venus dominates the east at dawn, while Mars is sinking in the west. By the second week of November, Mars will set before Venus rises.

Moon: Catch a waning crescent Moon near Venus in the east before dawn on October 13 and 14. For illustrations of gatherings of Moon and planets, see Sky Calendar, above.

At nightfall on October 22, catch a fat waxing crescent Moon, nearing First Quarter phase and so almost half full, near Jupiter and Saturn in SSW.

At nightfall on October 28 and 29, find waxing gibbous Moon near Mars well up in ESE. By 2½ hours before sunrise on the next mornings (October 29 and 30), Moon and red planet are low in the west.

On Saturday, October 31, the Halloween Full Moon sets just before sunrise, and rises again in evening twilight within half an hour after sunset. The Sun and Moon are at opposition and avoiding each other! But on Sunday morning, November 1, the Moon remains in view for more than 45 minutes after sunrise, and longer each morning.

Standard Time resumes on November 1, the first Sunday of November. Don’t forget to set your clocks back one hour. The result: Earlier sunsets by the clock, and darker early evening skies for sky watching, making the evening sky more accessible to younger students with early bedtimes. But we’ll get earlier sunrises too, so morning sky watching may become more difficult.

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Sky events in November 2020

Planets and seasonal stars at dusk (see evening twilight chart for November, above): Bright Jupiter is in SSW to SW, with Saturn 5.1° to 2.3° to its upper left. Anticipation builds! Mars is well up in ESE, higher as the month progresses. Stars: Summer Triangle of Vega, Altair, and Deneb moves west of overhead, chasing Antares below SW horizon and Arcturus below WNW horizon early in month. Fomalhaut is climbing in SE to SSE, while Capella climbs upward from NE horizon. Aldebaran appears very low in ENE before month’s end.

In deepening twilight on evenings in late November and early December each year, watch the sky not very far above horizon in ENE to E for the appearance of the beautiful Pleiades, or Seven Sisters, star cluster:

"Many a night I saw the Pleiades
Rising thro' the mellow shade,
Glittering like a swarm of fireflies,
Tangled in a silver braid."
~from Alfred Lord Tennyson, in Locksley Hall

This is an apt description of what you can witness annually in late November and early December, with the approach of nightfall. Binoculars provide wonderful views of the Pleiades! Rising in the east-northeast, within 14 degrees below the cluster, is the star Aldebaran. Although this star marks the eye of Taurus, the Bull, the name, translated from Arabic, means "the follower" (of the Pleiades). The Pleiades and Aldebaran are at opposition to the Sun on November 21 and December 1, respectively, as our planet Earth passes between those stars and the Sun. In 2020, our fast moving planet overtook Jupiter and Saturn in July, and Mars in October, resulting in those planets taking their turns at opposition. Stand outdoors and visualize the motions of Earth and the other planets in 3-D space, and try to predict how the appearance of the sky will change in coming weeks and months.

Planets and seasonal stars at dawn (see morning twilight chart for November, above): Venus is in ESE to SE, lower as month progresses. Mercury appears to lower left of Venus and brightens quickly early in month, while approaching 4° lower left of emerging Spica in a quasi-conjunction on November 2. Venus passes 4° north (upper left) of the same star in an actual conjunction on November 16. Mercury reaches its greatest altitude in morning twilight on November 10 and stays 13° lower left of Venus for ten mornings, November 9-18. This is a very favorable apparition of Mercury, so here’s an easy chance to see our solar system’s innermost planet! Stars: Sirius, the brightest star, is in SW, lower as month progresses. All of the bright stars of winter evenings described on October mornings have crossed into the western half of the sky. Arcturus is ascending in ENE to E, while Spica climbs past Venus into SE. Regulus is very high in SE to S. On November 21, Spaceship Earth lies between the Sun and the Pleiades, and is heading directly toward Regulus. The fast-moving inner planets Mercury and Venus are moving farther ahead of us and heading toward the far side of the Sun.

Moon in November: In morning sky, catch waning crescent Moon above Venus on November 12, and above Mercury on November 13. In the evening, see the waxing crescent Moon to lower right of Jupiter and Saturn on November 18, and to their left on November 19. On the evening of November 25, watch the waxing gibbous Moon pass 5° S of Mars. For illustrations of most of these events, and of the planet-planet and planet-star pairings mentioned above, see the November 2020 Sky Calendar.

At Full Moon on the night of November 29-30, part of the Moon will pass through the penumbra, or dusky outer portion of Earth’s shadow. At deepest eclipse, at 1:43 a.m. PST early Monday morning, November 30, the northern limb of the Moon will appear only slightly shaded. This is not a very noteworthy event, and if you choose to skip it, I won’t be disappointed! Aldebaran, red-orange eye of Taurus, will appear within 5° left of the Moon.

[A much more impressive lunar eclipse will occur on the morning of May 26, 2021. At 4:19 a.m. PDT, a colorful, totally eclipsed Moon will be low in SW, and the red star Antares, heart of Scorpius, will be within 7° to its left. That eclipse you should not miss!]

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Sky events in December 2020

(See evening twilight chart for December, above): Evening planets: Jupiter and Saturn form a striking, close pair in SW sky at dusk, within 2.2° apart on December 1, closing to just over 6 arcminutes (0.1°) apart on Monday, December 21, and reopening to nearly 1.2° apart on December 31. During December 12-29, the two giant planets appear within 1°, easily fitting within a low-power telescope field. Evenings around December 21, try higher magnifications for closer views of Jupiter’s cloud belts, system of four Galilean satellites, and Saturn with rings 21° from edge-on, all within one field! The pairing of Jupiter-Saturn in Capricornus on December 21, 2020 is their closest since a conjunction in Cancer in 1623, and until another in Capricornus in 2080. Jupiter-Saturn pairings occur at intervals of about 20 years, just over two-thirds of the way eastward (or nearly one-third of the way westward) around the zodiac on each successive occasion. At their next two pairings, in Virgo on the morning of October 31, 2040, and in Taurus within 5° S of the Pleiades on the evening of April 7, 2060, they’ll appear 1.1° apart. This month, Jupiter at mag. –2.0 is the brightest evening “star”,  following the Sun over WSW horizon by 3.3 hours on December 1, by 2.3 hours on December 21, and 1.7 hours on December 31. Saturn at mag. +0.6 is about one-tenth as bright.

Mars is high in SW sky at dusk. Fading from mag. –1.1 to –0.2 this month as Earth pulls away, the red planet ranks next in brightness after Jupiter among early evening’s “stars”; claims first place when Jupiter sets; and then drops back to second when Sirius appears in ESE. During December 1-31, Mars goes 10° east against the faint constellation Pisces. Binoculars help you enjoy these passages: Mars 1.0° S of 4.3-mag. Epsilon Psc on December 4; within 6° N of gibbous Moon on December 23; 4.5° S of 3.6-mag. Eta Psc on December 31; 2.5° N of 4.3-mag. Omicron Psc on January 1, 2021; and 1.6° N of 5.7-mag. Uranus on January 20.

Stars: The Summer Triangle of Vega, Altair, and Deneb is well up in western sky at dusk, and lower as the month progresses. Capella is ascending in NE, while Fomalhaut goes from S to SSW. Aldebaran, at opposition on December 1, begins month low in ENE, ascending into east, making way for the rising of Orion’s Betelgeuse and Rigel (with belt stars between them) in east.

(See morning twilight chart for December, above): Morning planets: Venus, rising 2.2 to 1.5 hours before sunrise, shines at mag. –4 in ESE to SE in twilight. Going east 1¼° daily, Venus passes 1.4° N of 2.8-mag. Alpha Librae on December 3; within 0.2° N of 2.6-mag. Beta Scorpii on December 18; and 5.6° N of 1st-mag. Antares on December 23. Mercury, 17° lower left of Venus on December 1, quickly drops into brighter twilight. Superior conjunction occurs December 19. Stars: Of winter’s bright stars in western sky, only the arch of Procyon, Pollux, Castor, and Capella remains visible by month’s end. Regulus is high in SW, to upper left of the arch. Arcturus is high in east, Spica in SE to SSE, Vega in NE. Deneb appears to lower left of Vega. Antares emerges in SE late in month.

Planets near the Moon. On Saturday December 12 at dawn, don’t miss 7-percent, old waning crescent Moon 4° upper right of Venus.  On Wednesday December 16 at dusk, catch 2.4-day-old, 7-percent young waxing crescent Moon 5° below Jupiter and Saturn. In this event just five days before the planets’ December 21 closest pairing, Ju-Sa will appear 32 arcminutes or one Moon-diameter apart! On Wednesday December 23 at dusk, see 9-day, 69-percent waxing gibbous Moon within 6° S of Mars.

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Sky events in January 2021

(See evening twilight chart for January 2021, above): Evening planets: Binoculars are recommended for following Jupiter and Saturn sinking into bright twilight, and forming a compact trio with emerging Mercury before the giants depart. You’ll also need clear skies and an unobstructed view!  Jupiter is very low in SW to WSW, sinking to the horizon by mid month. Saturn is to lower right of Jupiter, by 1.3° on January 1, increasing to 2.1° on January 8. Mercury, brighter than Saturn but fainter than Jupiter while emerging from the solar glare, passes 1.6° S (lower left) of Saturn on January 9, and 1.5° S (lower left) of Jupiter on January 11. Their most compact trio occurs on January 10, while Jupiter is still its highest and brightest member. That evening, Mercury is 1.7° lower left of Jupiter and Saturn is 2.3° to Jupiter’s lower right and 2.1° lower right of Mercury. By January 12 Mercury is the highest member, with Jupiter 2.3° to its lower right. On January 13, look earlier in twilight, perhaps half an hour after sunset,  to glimpse a thin 1-percent crescent Moon 4° lower left of Jupiter and 5.4° below Mercury. On January 14 at mid-twilight, the 4-percent crescent Moon is higher and easy to see, with Mercury within 8° to its lower right, and Jupiter within 5° lower right of Mercury. Both Jupiter and Saturn are gone after mid month, while Mercury climbs to its greatest elongation and its greatest altitude on the weekend of January 23-24. Mercury starts to fade noticeably at month’s end, as it goes through thinning crescent phases.

Mars is very high in southern sky at dusk all month, while moving 15° east against background stars, from Pisces into Aries. At nightfall on January 20, Mars appears 1.6° N of 5.8-mag. Uranus, making the fainter planet easy to locate. During January 10-29 they’re within 5° of each other, but be aware of the First Quarter Moon 6° from Mars on the evening of January 20, and the Full Moon lighting up the sky on January 28.

Bright stars at dusk: The Summer Triangle of Altair, Vega, Deneb, in order of departure in WNW, can still be seen in its entirety until mid-January, while the eastern sky is filling up with winter’s bright stars. Try to spot Sirius rising in ESE before losing sight of Altair setting just north of west, and you’ll see the Summer Triangle and the Winter Triangle of Betelgeuse, Procyon, Sirius simultaneously! Also visible is Fomalhaut, mouth of the Southern Fish, in the southwest, to the left of the planetary traffic jam.

Morning (see morning twilight chart for January 2021, above):   Venus, sinking to SE horizon before month’s end, is the only planet visible. A 3-percent crescent Moon will appear just 3° to upper right of Venus on January 11. Stars: Not many of the huge Winter Hexagon of stars remain. Procyon and Capella depart, and the Twin stars Pollux and Castor make it almost all the way down to the NW horizon. The Twin stars are at opposition to the Sun in the second week of January, so you can see them all night, from dusk until dawn. Regulus will be at opposition on Feb. 17-18, so it’s still visible well up in western sky on January mornings. We find the spring stars Arcturus and Spica crossing high in the southern sky. Spica will be at opposition on April 13-14. Antares, at opposition on May 30-31, is ascending in SE. In coming months, watch the bright zodiacal stars Regulus, Spica, and Antares drift over to the western sky as they approach opposition.

In morning twilight on January 13, the Sun is below the horizon in ESE. Spaceship Earth is heading in the direction of Spica. As we curve around the Sun, we will pass between Spica and the Sun in three months, on the night of April 13, and Spica will be visible all night.

In the coming months, Venus will pass superior conjunction on the far side of the Sun on March 26, and by late spring will begin to be seen in the evening sky, after sunset. In November and December 2021, Venus will be quite prominent in the evening sky.

In March through May 2021, Mars, though much faded from its former glory of October 2020, will still be easy to see in the evening sky, moving against interesting background stars of Taurus and Gemini, including the Pleiades, Aldebaran and the Hyades, and Pollux and Castor. We hope you’ll be watching! On the evenings of July 12 and 13, 2021, Venus will appear very close to Mars.

On August 1 and 19, 2021, the Earth will overtake Saturn and Jupiter, and those showpiece giant planets will be up all night, remaining visible evenings for nearly half a year thereafter. That means that in the final months of 2021, Venus, Jupiter, and Saturn will all be available for evening naked-eye and telescopic observation. I hope that conditions will then be right for teachers and students to get together to share and enjoy the wonderful views.

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Robert C. Victor originated the Abrams Planetarium Sky Calendar in October 1968, and has produced the October and November 2020 issues, accompanying this article. For subscription information and a sample of another month, visit www.abramsplanetarium.org/skycalendar/

Evening and morning twilight sky maps by Robert D. Miller, who did graduate work in Planetarium Science and later astronomy and computer science at Michigan State University. He remains active in research and public outreach in astronomy.

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