2021, May 10: Five Planets on Parade


May 10, 2021: Five planets are on display.  Jupiter and Saturn are visible in the southeastern sky before sunrise.  Brilliant Venus, Mercury, and Mars shine from the western sky after sunset.  Only the sun disrupts a continuous view of the five worlds.

Chart Caption – 2021, May 10: One hour before sunrise, bright Jupiter and Saturn are above the southeastern horizon.

by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 5:36 a.m. CDT; Sunset, 7:59 p.m. CDT.  Check local sources for sunrise and sunset times for your location.

Tomorrow the sun sets in Chicago at 8 p.m. CDT.  It sets at that time or later in Chicago until August 9.  That’s 90 days with a sunset on or after 8 p.m. CDT. 

For locations farther west in a time zone, the sun sets at a later time.

For example, on May 11, the sunset time in Sawyer, Michigan, is 8:56 p.m. EDT.  The town is on the eastern shore of Lake Michigan at the western edge of the eastern time zone. 

Sawyer is 50 miles east of Chicago and a time zone away – the difference in sunset times at the edges of their time zones.

Morning Sky

The planet parade starts after midnight, when Saturn rises over 4 hours before sunrise and Jupiter follows less than an hour later.

By an hour before sun up, bright Jupiter is over 20° above the southeast horizon.  The planet is brighter than all the other stars in the morning sky.

The Jovian Giant is slowly moving eastward compared to the sidereal background of Aquarius.  Use a binocular to find the star Iota Aquarii (ι Aqr on the chart).  Note the planet’s place each morning compared to that star.

Saturn – dimmer than Jupiter, but brighter than most of the stars in the morning sky – is over 16° to Jupiter’s upper right.  It is slowly moving eastward in Capricornus, 0.7° to the right of Theta Capricorni (θ Cap).

Use a binocular to see the starfield with the planets.

Capricornus – see the chart – resembles a misshapen boomerang or a stealth airplane.

Bright sunlight disrupts the parade as Jupiter and Saturn fade into the Carolina blue sky.  They lead the sun across the sky and set during the day.  Venus, Mercury, and Mars rise during daytime and follow the sun across the sky, only to easily appear to us in a sunless sky.

Evening Sky

Chart Caption – 2021, May 10: Brilliant Venus and Mercury are visible low in the west-northwestern sky, at 30 minutes after sunset.

Venus is the first planet in the evening parade to appear after sunset.  It was at its solar conjunction during late March.  It is still near the sun, first appearing low in the west-northwest about 30 minutes after sunset.  It is about 5° above the horizon.

Find an observing spot that has a clear natural horizon, that is free from trees, buildings and other structures.  A hillside or other elevated structures provide an excellent observing spot.

Mercury is bright and 9.0° to the upper left of Venus.  A binocular might be needed to initially locate the speedy planet.  Each night the planet is higher in the sky and dimmer.

Venus as an evening star article.

Read more about Venus in our summary document.

Chart Caption – 2021, May 10: Forty-five minutes after sunset, Venus, Mercury, and Mars are in the western sky.

By 45 minutes after sunset, Venus is a few degrees above the horizon, while Mercury is easily visible, over 10° above the west-northwest horizon. Mercury is in its best evening display of the year.

The star Aldebaran is to the upper left of Venus and lower left of Mercury.

At this hour Mars – among the stars of Gemini – is about 30° to the upper left of Mercury.

Here’s more about Mercury during May 2021.

Chart Caption – 2021, May 10: One hour after sunset, Mars is about one-third of the way up in the west in Gemini, 0.8° to the left of Mebsuta (ε Gem).

By an hour after sunset, Venus is setting.  Mercury is less than 10° above the horizon.  Mars is over one-third of the way up in the west below the stars Castor and Pollux. It is 0.8° to the left of Mebsuta (ε Gem on the chart).

Here’s more about Mars during 2021.

Venus is closing the gap to Mars. On July 12, Venus passes Mars in the western sky after sunset.  Since May Day, Venus has cut the distance to Mars by nearly 13°.  This evening, the gap between the planets is over 38°.

Venus sets later each evening, tonight an hour after sunset. The planet’s setting time lengthens about one minute each day.  A month from this evening, it sets over 90 minutes after sunset.

This evening, Mercury sets nearly two hours after sunset.  Mars follows Mercury over 2 hours later.

The parade begins again in the southeastern sky, when Saturn rises about 2 hours after Mars sets.

Again today, these notes do not mention the moon.  Where is it?

Detailed Note: Jupiter and Saturn continue their eastward treks compare to the starry background.  Find them low in the southeastern sky before sunrise.  One hour before sunup, bright Jupiter is over 20° up in the sky.  In the starfield, it is 1.4° to the upper left of ι Aqr.  Saturn is 16.3° of ecliptic longitude west of the Jovian Giant and to its upper right.  Through a binocular note its place compared to θ Cap. The Ringed Wonder is 0.7° to the right of the star.  Three planets are in the western sky after sunset.  Brilliant Venus is emerging from its solar conjunction on March 26.  It first appeared in the western sky on April 19.  Thirty minutes after sunset, it is nearly 5° above the west-northwest horizon.  Use a binocular to locate Mercury (m = −0.3), 9.0° to the upper left of Venus.  As the sky darkens further, look for Aldebaran, about 6° above the horizon.  Mercury is 7.9° to the upper right of the star.  At this time, Venus is slightly over 2° above the horizon. It sets one hour after sunset. Mars is 38.3° of ecliptic longitude east (to the upper left) of Venus, nearly in the middle of Gemini.  Since May Day, Venus has cut the distance to the Red Planet by nearly 13°. One hour after sunset, Mars is over 30° above the west horizon, 0.8° to the left of ε Gem.

Read more about the planets during May 2021.


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