Astronomy

2020, October 20: Morning Star Venus, Evening Lunar Crescent

Advertisements
2020: October 20-22: The moon is visible in the southern sky after sunset. On October 20, it is visible between Antares and Kaus Borealis. October 21, the lunar crescent is between Kaus Borealis and Nunki. On October 22, the moon is near Jupiter and Saturn.

Brilliant Morning Star Venus shines from the east-southeast before sunrise.  It is in front of the stars of Leo.  In the evening, the lunar crescent is in the southwest, not far from Jupiter and Saturn that are approaching their Great Conjunction on December 21, 2020. Bright Mars shines from the evening’s eastern sky.

by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 7:09 a.m. CDT; Sunset, 6:01 p.m. CDT.  Check local sources for sunrise and sunset times in different locations.

Morning: Morning Star Venus continues to gleam in the eastern sky before sunrise.  It is over 11° to the lower right of Denebola – the Tail of Leo.  When you extend your closed fist to arm’s length, then it should cover nearly all the space between the brilliant planet and the star.  Use a binocular to see Venus among the dimmer stars.  Bright Mars is very low in the west.  Early next month, Venus rises as Mars sets, a Venus – Mars opposition.  The planets are on opposite parts of the sky.  What is the last date that you can see them together in the morning sky?  The Red Planet returns to the eastern sky after sunset. See our detailed chart for Venus in October here.

Detailed morning note: One hour before sunrise, Venus is over 22° up in the east-southeast, moving eastward in Leo. Among the stars it is 1.9° below Sigma Leonis (σ Leo) and 2.0° to the upper left of Tau Leonis (τ Leo). Through a telescope, Venus is 13.9” in apparent diameter and 78% illuminated – a morning gibbous. Mars – about 4° up in the west – is 170.8° of ecliptic longitude west of Venus.

See our summary about Venus during October 2020 and the feature article  about Venus as a Morning Star.

Evening: In the south-southwest about an hour after sunset, the crescent moon – 4.2 days after its New moon phase and 23% illuminated – is between Antares – the Heart of the Scorpion – and the Teapot of Sagittarius.  The Teapot, along with the Big Dipper, Little Dipper, Sickle of Leo, and many other shapes, is an asterism.  An asterismis group of stars that makes a familiar shape that is often part of a constellation.  Kaus Borealis (λ Sgr) is the star at the top of the Teapot shape.  Use a binocular for a clearer look.  Jupiter and Saturn are farther to the left of the star.  The planets are 6.0° apart.  They are moving eastward compared to the starry background.  During the next few weeks, watch Jupiter dramatically cut the distance to Saturn in a prelude to their Great Conjunction.  Jupiter sets in the southwest at about 11 p.m. and Saturn follows about 30 minutes later. Bright Mars is in the east-southeast among the dim stars of Pisces.  It is retrograding – moving westward compared to the starry background.  This is an illusion from our planet passing Mars.  Opposition was a week ago. The Red Planet is south near midnight and sets in the west before sunrise.

Detailed evening note: One hour after sunset the moon (4.2d, 23%) – nearly 16° up in the south-southwest – is above a line from Antares to Kaus Borealis (λ Sgr, m = 2.8), the star at the top of the lid of the Teapot of Sagittarius.  The gaps: Moon – Kaus Borealis, 10.9°; Moon – Antares, 15.9°.  Look carefully for Antares as it is only 6° in altitude in the southwest.  Farther eastward, Jupiter is about 25° up in the south-southwest.  The Jupiter – Saturn gap is 6.0°.   In the starfield, Jupiter is 3.6° to the lower left of π Sgr and 0.8° to the lower right of 50 Sgr.  Saturn is 1.8° to the lower left of 56 Sgr.  At this hour, Mars is nearly 14° in altitude in the south-southeast, 89.3° of ecliptic longitude east of Jupiter.  An hour later, the Red Planet is nearly 25° up in the east-southeast.  It is left of a line from 80 Psc to 89 Psc.  The planet is 1.2° to the lower left of 80 Psc and 1.8° above 89 Psc. Through a telescope, Mars is 21.8” across.

For more about the Great Conjunction, read our feature article. This is the closest Jupiter – Saturn conjunction since 1623.

Read more about the planets during October.

Leave a Reply