2021, April 3: AM Planet Pair, Gibbous Moon, PM Mars

April 3, 2021:  Before sunrise, the bright gibbous moon is near the top of the lid of the Teapot of Sagittarius.  Farther east, Jupiter and Saturn are in front of the stars of Capricornus.  In the evening, Mars continues its eastward march in Taurus.  It is between Aldebaran and Elnath this evening.

by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 6:30 a.m. CDT; Sunset, 7:19 p.m. CDT.  Check local sources for sunrise and sunset times for your location.

Morning Sky

Step outside this morning during twilight to find the slightly gibbous moon low in the south.  The lunar orb is near the Teapot of Sagittarius.  The shape is an asterism, a group of stars that look like a familiar object – such as the Big Dipper.

Sagittarius is a centaur, part human and part horse.

The moon is near Kaus Borealis (λ Sgr on the chart), “the northern part of the bow” of the centaur.

Farther east Jupiter continues to move away from Saturn.  Brighter Jupiter is over 8° above the east-southeast horizon at this hour.  Saturn is dimmer and 12.1° to the upper right of the Jovian Giant.

To estimate the distance between the two planets.  Extend your fist.  The angular distance from your thumb knuckle to pinky finger knuckle is about 10°.  Move your fist to make it horizontal.  Orient it so that one knuckle is near Jupiter.  Angle your fist up a little bit.  Saturn will be near the other knuckle as you observe your fist against the morning sky.

In the starfield, Jupiter is 1.9° to the upper left of Deneb Algiedi (δ Cap on the chart), while Saturn is 2.5° to the upper right of Theta Capricorni (θ Cap).  Use a binocular to spot the stars.

During April watch these slow-moving planets move eastward compared to these two stars.

Evening Sky

One hour after sunset, Mars is over halfway up in the west in front of the stars of Taurus.  It is on a line from the constellation’s brightest star, Aldebaran, to Elnath, the Bull’s Northern Horn.  It is 6.0° to the lower left of Elnath and 10.7° to the upper right of Aldebaran.

Here’s more about Mars during 2021.

Read about Mars during April.

Detailed Note: One hour before sunrise, the slightly gibbous moon (21.0d, 61%) is over 20° in altitude above the southern horizon.  The lunar orb is 5.1° to the right of Kaus Borealis (“the northern part of the bow”, λ Sgr, m = 2.8), the star at the top of the lid of the Teapot of Sagittarius.  Farther east, Jupiter is over 8° up in the east-southeast.  It is 1.9° to the upper left of δ Cap.  Saturn is 12.1° to the upper right of Jupiter and 2.5° to the upper right of Theta Capricorni (θ Cap, m = 4.0). One hour after sunset, Mars is over halfway up in the west among the stars of Taurus.  The planet is on a line from Aldebaran (α Tau, m = 0.8) to Elnath.  It is 6.0° to the lower left of Elnath and 10.7° to the upper right of Aldebaran.

Read more about the planets during April 2021.