March 31, 2021: Arcturus rises at sunset and can be found low in the east-northeast an hour later. Mars marches eastward in front of the stars of Taurus. The bright gibbous moon rises low in the east-southeast near midnight.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 6:35 a.m. CDT; Sunset, 7:15 p.m. CDT. Check local sources for sunrise and sunset times for your location.
The bright star Arcturus, “the bear guard,” rises at sunset. An hour after sunset, find it about 10° up in the east-northeast.
Arcturus is the third brightest star visible in the skies of Earth, and it is the brightest in the northern half of the sky. The star is part of Boötes, the Herdsman. In some artwork, Boötes is chasing after the Big Bear, Ursa Major.
The constellation’s pattern resembles a kite. It is better seen when the star and the pattern are higher in the sky. This evening it lies along the horizon to the left of Arcturus.
Unlike planets that rise at sunset, Arcturus is far north of the plane of the solar system. It appears in the sky for over 14.5 hours, compared to the 12.7 hours of daylight.
The farther north a celestial object, the longer it stays in the sky. When the sun rises and sets north of the equator, the days are longer than it is south of the equator.
Arcturus is south a few hours after midnight. As morning twilight begins, the star is over two-thirds of the way up in the sky in the southwest.
Mars is the lone bright evening planet. It is over halfway up in the west, above the “V” of Taurus, made by Aldebaran and the Hyades star cluster. The planet moved nearly 18° eastward during the month.
Mars is moving toward the Bull’s horns, marked by Elnath and Zeta Tauri (ζ Tau). This evening the planet is 7.4° below Elnath.
Use a binocular to find the starry background with Mars. This evening, the Red Planet is 4.1° to the upper left of Tau Tauri (τ Tau) and 2.7° to the upper right of Iota Tauri (ι Tau).
As midnight approaches, the bright moon is about 5° above the east-southeast horizon, 13.0° below Zubeneschamali, “the northern claw” of the scorpion.
Here’s more about Mars during 2021.
Read about Mars during March.
Detailed Note: One hour before sunrise, the bright gibbous moon (18.0d, 90%) is nearly 25° up in the southwest, 2.6° to the upper left of Zubenelgenubi. Farther eastward, Saturn is over 12° above the southeastern horizon. Jupiter – over 7° in altitude above the east-southeastern horizon – is 11.7° of ecliptic longitude east of Saturn. Use a binocular to see the planets against the starry background. Saturn is 2.8° to the upper right of θ Cap, while Jupiter is 5.2° to the lower left of ι Cap. You may have already spotted Nashira (“the lucky star of the verdant fields at the end of summer,” γ Cap, m = 3.6) and Deneb Algiedi (“the kid’s tail, δ Cap, m = 2.8) below Jupiter. The planet and the stars make a nice triangle. Jupiter is 2.1° to the upper left of Nashira and 2.0° above Deneb Algedi. Arcturus (“the bear-guard,” α Boo, m = −0.1) rises at sunset. One hour after sunset, Mars is less than 50° up in the west, in Taurus above the “V” made by Aldebaran and the Hyades star cluster. The planet moved eastward 17.7° during the month. Use a binocular to spot it 4.1° to the upper left of τ Tau, 2.7° to the upper right of ι Tau, and 7.4° below Elnath. As midnight approaches, the bright moon (18.8d, 83%) is less than 5° up in the east-southeast, 13.0° below Zubeneschamali (“the northern claw,” β Lib, m = 2.6).
Read more about the planets during March 2021.
October 23, 2021: This morning the bright moon is near the Pleiades star cluster. Mercury is making its best morning appearance. In the evening sky, Venus, Jupiter and Saturn are easy to spot.
October 22. 2021: Speedy Mercury is low in the east before sunrise. It is putting on its best morning performance of the year. Arcturus, in the east-northeast, is about the same altitude as Mercury.
October 21-November 1, 2021: Brilliant Venus steps through Ophiuchus to the upper left of the star Antares in the southwest after sunset . Afterward, the planet steps farther eastward.
October 21, 2021: The bright moon is low in the west about an hour before sunrise. Mercury is in the east at about the same altitude as Arcturus. Venus, Saturn, and Jupiter shine from the evening sky.
December 18, 2021: This is the anticipated launch date of the James Webb Space Telescope, the largest and most sophisticated space telescope view the universe.