2021, October 17:  Arcturus, Mercury, Morning, Evening Planet Pack

October 17, 2021: Arcturus is making its first morning appearance in the eastern sky before sunrise, while Mercury is beginning its best morning appearance of the year.  The gibbous moon, Jupiter, Saturn, and Venus are strung across the sky after sundown.

2021, October 17: Arcturus is making its first morning appearance in the east-northeast before sunrise. Mercury is beginning its best morning appearance of the year.
Chart Caption – 2021, October 17: Arcturus is making its first morning appearance in the east-northeast before sunrise. Mercury is beginning its best morning appearance of the year.

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by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 7:06 a.m. CDT; Sunset, 6:06 p.m. CDT.  Check local sources for sunrise and sunset times for your location.

DAILY PLANET NOTES FOR OCTOBER 2021

VENUS AS AN EVENING STAR 2021

Note the sunrise times for the Chicago area and other similar latitudes, daylight has decreased to 11 hours.  In less than two weeks, darkness – the time from the end of evening twilight to the beginning of morning twilight – exceeds the length of daylight.  Read the linked article or listen to the associated podcast for more details.

Morning Sky

The star Arcturus is making its first morning appearance in the east-northeast about 40 minutes before sunrise.  The date of the first appearance is determined by weather and transparency of the sky.  Additionally, Mercury is beginning to make its best morning appearance of the year.  This morning the planet is dim, but it brightens rapidly during the next few days.  The planet is higher than Arcturus, but considerably dimmer this morning.  It is a binocular object, although this morning this is a challenging view.

During this season, Arcturus appears in the western sky after sunset.  Follow the Big Dipper’s curved handle to the star.  An hour after sunset, Arcturus is about 15° up in the west.  The dipper is in the northwest.  The star sets and then rises in the east-northeast before sunrise.

Arcturus is 25° farther north than the sun today.  Because of the star’s location and the earth’s place in its solar orbit, the star can be seen after sunset and before sunrise at this season.

The star Spica is at its solar conjunction today.  It begins to appear in the morning sky early next month

Evening Sky

2021, October 17: The moon, Jupiter, and Saturn are strung across the southeastern sky after sunset.
Chart Caption – 2021, October 17: The moon, Jupiter, and Saturn are strung across the southeastern sky after sunset.

The bright moon, Jupiter, Saturn, and Venus are strung across the sky from east-southeast to the southwest.

The bright moon is over 15° above the east-southeast horizon.  It is approaching its full phase, 93% illuminated.

Bright Jupiter is over 30° to the upper right of the gibbous moon and Saturn is over 15° beyond Jupiter.

Saturn is slowly moving eastward compared to the background stars.  Jupiter’s retrograde ends tomorrow.  Saturn slightly closes the gap during the next several evenings.  Then Jupiter moves faster eastward than Saturn and pulls away from the Ringed Wonder.

2021, October 17: Venus is 1.8° to the upper left of Antares.
Chart Caption – 2021, October 17: Venus is 1.8° to the upper left of Antares.

Brilliant Evening Star Venus is low in the southwest, 1.8° to the upper left of Antares.  The planet continues to step eastward compared to the Scorpion’s stars.

Detailed Daily Note: Begin looking for Arcturus, low in the east-northeast about 40 minutes before sunrise.  It is making its first morning appearance.  Spica is at its conjunction with the sun today.  Forty-five minutes after sunset, Venus, over 10° up in the southwest, is 1.8° to the upper left of Antares.  The bright moon (11.5d, 93%) is over 16° up in the east-southeast.  Bright Jupiter, over 27° above the south-southeast horizon, is over 30° to the upper right of the lunar orb and 15.4° to the left of Saturn.  Saturn is gently moving eastward compared to the starry background, while Jupiter slows moving westward.  Tomorrow the planet reverses its retrograde and begins to move eastward.  Two hours after sunset, the moon is less than one-third of the way up in the southeast.  Look for Fomalhaut, about 15° up in the south-southeast and 23.0° to the lower left of Jupiter.  In the starfield, Jupiter is 3.8° to the lower right of dim μ Cap, 2.1° to the upper right of Deneb Algedi, and 1.4° above Nashira.  Saturn, nearly 29° up in the south, west of the meridian, is 1.4° to the lower right of υ Cap.  Use a binocular to see the sidereal backdrop with the bright moonlight.

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