2021, April 30: Bright Moon, Bright Planets, Jupiter, Saturn


April 30, 2021: The bright, morning gibbous moon is between Antares and Sagittarius, among the stars of Ophiuchus.  Bright Jupiter and Saturn are in the southeastern sky before sunrise.

Chart Caption – 2021, April 30: The bright moon is in the southern sky before sunrise, between Antares and Kaus Borealis (λ Sgr).

by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 5:48 a.m. CDT; Sunset, 7:49 p.m. CDT.  Check local sources for sunrise and sunset times for your location.

Daylight is one minute longer than 14 hours at this latitude today.  During April, daylight increased 77 minutes.

This morning the bright moon, 85% illuminated is about 20° up in the south in front of the stars of Ophiuchus, between Sagittarius and Scorpius.

The plane of the solar system, known as the ecliptic, is the path that the sun, moon, and planets appear to move along.  The sun’s motion is from our revolution around that star.  The planets’ motions compared to the sidereal background is from the combined motion of our world and the sun’s satellites.

The ecliptic is about 3 times longer in Ophiuchus than it is in Scorpius. This morning the moon is near the Sagittarius-Ophiuchus border.  The Ophiuchus-Scorpius border is to the upper right of Antares, “the rival of Mars, the brightest star in Scorpius.

In mythology, Ophiuchus was a snake holder, possibly a predecessor of the modern physician.

From the moon’s position, the constellation extends upwards over 40°, although the pattern is an irregular shape.

This morning the moon is 16.0° to the upper left of Antares, “the rival of Mars,” and 10.6° to the right of Kaus Borealis, “the northern part of the bow,” (λ Sgr on the chart).

As the star’s name indicates, Sagittarius is referred to as the “Archer,” with a bow pulled back with its arrow ready to fly toward its target.

Chart Caption – 2021, April 30: Bright morning planets are in the southeastern sky before sunrise.

Bright morning planets, Jupiter and Saturn, are in the southeast before sunrise.  Jupiter, brighter than all the stars in the sky this morning, is nearly 17° up in the southeastern sky.  It is trekking eastward in Aquarius.  The background stars are not bright.  Use a binocular to spot them.

Jupiter is 4.8° to the upper left of Deneb Algiedi, “the kid’s tail” (δ Cap on the chart), 2.1° to the lower left of Mu Capricorni (μ Cap), and 1.5° to the upper right of ι Aqr.

Saturn is dimmer than Jupiter, but easily seen in the sky.  The Ringed Wonder is 15.2° west (to the right in the northern hemisphere) of the Jovian Giant.  During April, Jupiter increased the gap to Saturn by over 3°.

Saturn is about the same altitude as Kaus Borealis.

Saturn is slowly moving eastward compared to the stars of Capricornus.  It is 1.0° to the right of Theta Capricorni (θ Cap).

Detailed Note: One hour before sunrise, the moon (18.3d, 85%) is over 20° above the southern horizon. The lunar orb is 16.0° to the upper left of Antares and 10.6° to the right of Kaus Borealis (λ Sgr, m = 2.8), the star at the top of the lid of the Teapot of Sagittarius. At this hour, Jupiter is nearly 17° above the southeast horizon.  It is moving eastward in Aquarius, 4.8° to the left of Deneb Algiedi, 2.1° to the lower left of μ Cap, and 1.5° to the upper right of ι Aqr.  Saturn is 15.2° of ecliptic longitude west of Jupiter, to the upper right of the Jovian Giant in the sky.  Saturn is slowly creeping toward θ Cap.  This morning the gap is 1.0°.  The sun is in the sky for one minute longer than 14 hours.  Twenty minutes after sunset, brilliant Venus is over 4° above the west-northwest horizon.  Have you observed it without a binocular?  Mercury (m = −1.1) is 4.5° above Venus.  As the sky darkens further, Mars is less than 40° up in the west among the stars of Gemini.  It is 2.5° to the upper right of Propus and 2.4° to the right of Tejat Posterior.  Use a binocular to locate the star cluster M35, 2.4° to the lower right of Mars.  The month ends with Mars 44.5° of ecliptic longitude east of Venus. As Venus becomes easier to see, watch it close the gap to Mars.

Read more about the planets during April 2021

2021, July 26: Evening Sky, Mars Closes In

July 26, 2021:  Four bright planets are in the evening sky.  Mars closes in on Regulus for their conjunction in three evenings.  Brilliant Evening Star Venus appears to the upper left of the impending Mars – Regulus conjunction.  Saturn and Jupiter are low in the southeastern sky after sunset.

2021, July 25: Evening Sky, Mars on Final Approach

July 25, 2021:  Four evenings before its conjunction with Regulus, find Mars in the western sky to the lower right of Venus.  As the calendar day ends, look for the moon below bright Jupiter.

2021, July 24: Four Evening Planets, Moon

July 24, 2021: After sunset, Venus and Mars are in the western sky.  A little later during evening hours, the moon is near Jupiter and Saturn in the southeast.

2021, July 29: Jupiter – Mars Opposition

July 29, 2021:  Jupiter and Mars are 180° apart along the ecliptic.  Dim Mars sets in the west-northwest as Jupiter rises in the east-southeast.  This event signals that soon both appear in the sky simultaneously.

Categories: Astronomy, Sky Watching

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