2021, May 6: 24 Hours, 5 Planets, Moon


May 6, 2021: During a 24-hour period, the five bright planets and the moon are visible.  Before sunrise this morning, Saturn, Jupiter, and the crescent moon are lined up in the southeast.  After sunset, brilliant Evening Star Venus is visible after sunset.  As the sky darkens Mercury, then Mars, appears in the western sky.

Chart Caption – 2021, May 6: The crescent moon, Jupiter, and Saturn are lined up in the southeast an hour before sunrise.

by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 5:40 a.m. CDT; Sunset, 7:55 p.m. CDT.  Check local sources for sunrise and sunset times for your location.

During the next 24 hours, look for the moon and the five bright planets.  The planetary quintet is visible each morning and evening for most of the month before Mercury disappears back into the sun’s brilliance.

Morning Sky

An hour before sunrise, the crescent moon, 25% illuminated, is low in the east-southeast, 8.0° above the horizon.  Bright Jupiter is nearly 19° to the upper right of the lunar slice.

Jupiter is the brightest “star” in the morning sky.  It is nearly 20° up in the southeast, about the same distance above the horizon that the moon is from the Jovian Giant.

Saturn is nearly 16° to the upper right of Jupiter.  The Ringed Wonder is brighter that all the stars in the immediate area, except for Jupiter.

Jupiter and Saturn are slowly moving eastward compared to the starry background.  Jupiter is moving eastward in Aquarius.

Saturn, in Capricornus, is slowing to begin its retrograde motion next week.

Retrograde motion is an illusion from our faster moving home world catching and moving past a slower moving outer planet.  Saturn appears to be moving eastward, then it slows, and it begins to move westward for a time compared to the stars.  After a period of time, the planet begins its eastward motion again.

Before the invention of the telescope and sensitive measures to demonstrate Earth’s revolution around the sun, the cause of retrograde motion was the cosmological problem of our ancestor-scientists.

Evening Sky

Chart Caption – 2021, May 6: Thirty minutes after sundown, brilliant Venus and Mercury are visible in the west-northwest. Use a binocular to initially locate them.

After sunset, brilliant Venus is low in the west-northwest after sunset.  With a binocular, begin looking at 30 minutes after sunset.  The planet is about 4° above the horizon.  Can you see it without the binocular’s assistance?

Mercury is visible through a binocular at this time interval after sunset.

Read more about Venus in our summary document.

Chart Caption – 2021, May 6: Forty-five minutes after sunset, three planets are visible. Find a clear horizon to see Venus.

Fifteen minutes later, the speedy planet is 9° above the west-northwest horizon.  (Venus is still visible if you have a good view of the natural horizon.)

At this time, Mars is visible over 30° to the upper left of Mercury.  The chart above shows the brighter stars visible with the planetary trio.

For those interested in viewing and identifying stars visible during this phase of twilight, the detailed notes include what to see.

Here’s more about Mercury during May 2021.

Chart Caption – 2021, May 6: One hour after sunset, Mars is in the western sky, beneath Castor and Pollux, 3.4° above Tejat Posterior (μ Gem) and 2.0° to the lower right of Mebsuta (ε Gem).

By one hour after sundown, Mercury is over 6° above the west-northwest horizon.

Mars’ starry background, Gemini, is easier to see.  The Red Planet is under Castor and Pollux, the Twins, near the feet.

This evening Mars is 3.4° above Tejat Posterior, “the heel” (μ Gem on the chart) and 2.0° to the lower right of Mebsuta, “the outstretched paw of the lion,” (ε Gem).

Mars is marching eastward along the plane of the solar system that runs diagonally from the lower right corner of the chart to upper left.

During the next few weeks Mars moves beneath Castor and Pollux, ending the month to the lower left of Pollux.

Here’s more about Mars during 2021.

Tomorrow morning the daily planet parade continues.  The moon is visible a little closer to sunrise.

Detailed Note: One hour before sunrise, bright Jupiter (m = −2.3) is nearly 19° up in the southeast.  It is 1.3° to the upper left of ι Aqr.  The crescent moon (24.6d, 25%), 8.0° above the east-southeast horizon, is nearly 19° to the lower left of Jupiter. Saturn is nearly 16° to the upper right of Jupiter and 0.8° to the right of θ Cap. Thirty minutes after sunset, Venus is about 4° up in the west-northwest.   Mercury is 7.9° to the upper left of Venus.  Forty-five minutes after sunset, Mercury is nearly 9° above the west-northwest horizon.  This speedy planet passes 8.0° to the upper right of Gamma Tauri (γ Tau, m = 3.6), the star at the bottom of the “V” of Taurus, made by Aldebaran and the Hyades star cluster. Also note that Mercury is below a line from Aldebaran (α Tau, m = 0.8) that extends through Epsilon Tauri (ε Tau, m = 3.5).  The planet is 6.0° to the lower right of ε Tau.  Use a binocular to spot the starfield.  One hour after sunset, Mercury is still over 6° up in the sky.  Mars is over one-third of the way up in the west as it moves toward the Castor and Pollux.  It is 3.4° above μ Gem and 2.0° to the lower right of ε Gem.

.Read more about the planets during May 2021.


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