2021, May 25: Morning Planets, Jupiter, Saturn

May 25, 2021:  The bright moon is in the southwest this morning.  Bright Jupiter and Saturn are in the southeastern sky before sunrise.  Jupiter, brighter than all the stars this morning, is moving eastward among the stars of Aquarius.  Saturn, to the upper right of Jupiter, is retrograding in Capricornus.

by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 5:22 a.m. CDT; Sunset, 8:14 p.m. CDT.  Check local sources for sunrise and sunset times for your location.

Morning Sky

Tomorrow morning a lunar eclipse occurs, although it sets in the Americas before it is complete.  The farther west, the more of the eclipse is visible.  The western US and Canada see the moon enter the total phase, but it is low in the sky, and it sets soon after.

This morning the bright moon is low in the west-southwest.

Bright morning planets, Jupiter and Saturn, are in the southeast before sunrise this morning.

Saturn rises over 4.5 hours before sunup.  Jupiter follows about 100 minutes later.

By an hour before sunrise, Saturn is about one-third of the way up in the sky above the south-southeast horizon.  It is retrograding in Capricornus, 0.6° to the right of Theta Capricorni (θ Cap on the chart).

Retrograde motion is an illusion as our faster moving Earth over takes and passes between an outer planet and the sun.  Sun, Earth, and Saturn are along an imaginary line on August 2.  This is known as opposition.  The sun and Saturn are in opposite directions in the sky.

At opposition, Saturn rises in the eastern sky, when the sun sets in the western sky.  The planet is south near midnight, while the sun is in that direction at noon.  The planet sets in the western sky at sunrise. The planet is in the sky all night long.

The planet is closest to Earth around the time of opposition.  Because the planets’ orbits are not perfect circles, the closest separations do not necessarily coincide with the nights of opposition.

Jupiter begins to retrograde next month, and its opposition is August 19.

This morning Jupiter is the brightest star in the sky. It is nearly 18° to the lower left of Saturn.  Use a binocular to spot the background stars.  This morning the Jovian Giant is 2.4° to the upper left of Iota Aquarii (ι Aqr), 4.3° to the lower right of Ancha (θ Aqr) – “the hip” – and 4.6° to the upper right of Sigma Aquarii (σ Aqr).

Jupiter and Saturn fade into the bright, blue sky as the sun appears in the eastern sky.  They set during the daytime, but they are back in the southeastern sky before sunrise tomorrow morning.

Articles and Summaries.

• Venus as an Evening Star
• Venus Evening Star (Summary)
• Mercury during May 2021
• Mars during 2021 (Summary)
• Mars during May 2021
• Planets during May 2021

Detailed Note: One hour before sunrise, Saturn – retrograding slowly in Capricornus – is less than 30° above the south-southeast horizon.  It is 0.6° to the right of θ Cap.  Bright Jupiter is 17.6° of ecliptic longitude to the east and lower left of the Ringed Wonder.  The Jovian Giant is 26.0° up in the southeast, 2.4° to the upper left of ι Aqr, 4.3° to the lower right of θ Aqr, and 4.6° to the upper right of σ Aqr.  The moon is at perigee (222,061 miles) at 8:50 p.m. CDT.  A perigee full moon with an eclipse occurs tomorrow morning. Three evening planets continue their display in the western sky after sunset.  As the sky darkens, the trio makes a diagonal line above the horizon. Thirty minutes after sunset, brilliant Venus – over a month after is appearance in the evening sky, is nearly 8° up in the west-northwest.  Use a binocular to locate fading Mercury (m = 1.6), 3.3° to the upper left of the brilliant planet. The nearly full moon (14.3d, 100%) is about 10° above the southeast horizon. By 45 minutes after the sun sets, the planet trio is visible to the unaided eye.  Albeit low, Venus is 5° above the horizon, and Mercury is nearly 8° up and to the upper left of Venus. Spot Elnath, 4.4° to the upper right of Mercury.  Mars – less than one-third of the way up in the west – is nearly 26° to the upper left of Mercury.  In the southeast, the moon is 3.2° to the upper right of Graffias (β Sco, m = 2.5).  An hour after sunset, Venus’ altitude is less than 3°, while Mercury is over 5° above the west-northwest horizon.  In the starfield, Mars is 1.8° to the upper right of δ Gem and 6.4° to the lower left of Pollux.  The setting time intervals for the planets this evening: Venus, 78 minutes (m) after sunset; Mercury, 95 m; and Mars, 204 m.