2024, March 17:  Look for Mercury

Astronomy, Sky Watching

March 17, 2024: Look for Mercury in the western sky after sunset.  Like the other planets, it looks like a bright star.  Jupiter is above the speedy planet.

December 27, 2017: Jupiter, Mercury and Mars
December 27, 2017: Jupiter, Mercury and Mars

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by Jeffrey L. Hunt

Chicago, Illinois: Sunrise, 6:58 a.m. CDT; Sunset, 7:00 p.m. CDT.  Check local sources for sunrise and sunset times. Times are calculated by the US Naval Observatory’s MICA computer program.

Summaries of Current Sky Events
Summary for Venus as a Morning Star, 2023-24

Here is today’s planet forecast:

Morning Sky

Venus, Mars, and Saturn

Distant Titan, its northern hemisphere drenched in the sunlight of late spring, hangs above Saturn's rings. What might at first glance look like a gap between the rings and the planet is actually Saturn’s shadow. During most of Saturn's long year, the projection of the planet's shadow extends well beyond the edge of the A ring.
Photo Caption – Distant Titan, its northern hemisphere drenched in the sunlight of late spring, hangs above Saturn’s rings as seen from the Cassini spacecraft. What might at first glance look like a gap between the rings and the planet is actually Saturn’s shadow. (NASA photo)

Venus, Mars, and Saturn are in bright sunlight.  Saturn is nearly impossible to see, rising 26 minutes before the sun.

Among the three morning planets, Mars rises earliest, 67 minutes before the sun. At forty minutes before daybreak, the planet is nearly 5° above the horizon.  It is not yet visible without an optical assist.  Find a clear view of the east-southeast horizon.

Venus rises nearly 30 minutes after Mars.  The brilliant planet can be found in brighter twilight near the horizon if spotted from a clear view of the east-southeast.  It is over 3° up at 20 minutes before daybreak.

Neptune is at solar conjunction.  The farthest planet in the current solar system model, is very difficult to see under normal circumstances.  It is about twice as far away from the sun as Uranus, visible in the sky in Jupiter’s vicinity.

Evening Sky

Look for Mercury

Look for Mercury
Chart Caption – 2024, March 17: Mercury and Jupiter are in the west after sundown.

After nightfall, look for Mercury in the western sky.  Find a clear observing spot looking toward the west direction.  At 45 minutes after sundown, it is nearly 7° above the horizon.  It is bright enough to see without optical assistance, but a binocular is helpful to find it.  Then look without the optical help. The planet resembles a bright star. 

The planet’s altitude is less than “one fist” above the horizon.  Make a fist and extend your arm with your thumb on top.  The distance from your thumb knuckle to your pinky finger is about 10°.  For the next two weeks, Mercury is about that height above the horizon at 45 minutes after sunset.  The planet’s peak altitude is nearly 10° in a week when it reaches greatest elongation.

The planet is dimming each evening, but it is easily visible.  This is the best evening appearance of the year.

Do not confuse Mercury with bright Jupiter that is less than halfway up in the west, about 30° or three fists (stack them, like the action of climbing a rope) to Mercury’s upper left.  Hamal, Aries’ brightest star, is over 10° to the lower right of Jupiter.

At this hour the slightly gibbous moon is high in the southern sky.

Fifteen minutes later, more stars are visible and Mercury is lower, less than 5° above the horizon.

Jupiter with the Stars

2024, March 17: One hour after sunset, Jupiter is in the western sky below Taurus.
Chart Caption – 2024, March 17: One hour after sunset, Jupiter is in the western sky below Taurus.

Bright Jupiter is noticeably east or above a line that connects Hamal to Menkar, part of Cetus.  Aldebaran, the Pleiades star cluster, and the Hyades cluster are above the bright planet.  Use a binocular to see them in this moonlight.

Jupiter, Uranus through a Binocular

2024, March 17: Jupiter and Uranus are in a binocular’s field of view.
Chart Caption – 2024, March 17: Jupiter and Uranus are in a binocular’s field of view.

Use a binocular to see Jupiter and Uranus in the same field of view.  Place Jupiter toward the lower right of the field.  The Jovian Giant is about halfway from Omicron Arietis (ο Ari on the chart) to Sigma Arietis (σ Ari).

Uranus is toward the upper left in the field of view, to the upper left of dimmer 53 Arietis (53 Ari).  The planet resembles an aquamarine star.  A telescope with high magnification is needed to see the planet’s globe.

Uranus is visible in a dark location without any optical assistance.  Its brightness is near the limit of human eyesight.  Initially, it was identified as a star, but in 1781, the planet was observed to move from night to night against the starfield.  If you have been watching Uranus with the binocular during the past few weeks, it has moved eastward slightly compared to 53 Arietis.  Congratulations, you have experienced one of the challenges of a planet hunter by watching for small movements of distant objects against the starfield.

Gemini Moon

2024, March 17: The gibbous moon is near Castor and Pollux, high in the south during the early evening.
Chart Caption – 2024, March 17: The gibbous moon is near Castor and Pollux, high in the south during the early evening.

Farther eastward, the gibbous moon, 59% illuminated, is high in the southern sky.  Tonight, it is in front of Gemini, 13.4° to the lower right of Castor and 15.5° to the lower right of Pollux, the pattern’s brightest stars.

Jupiter sets in the west-northwest over four hours after sunset and before midnight.  The moon follows Jupiter westward from Earth’s rotation.  The lunar orb sets after midnight and three hours before sunup.

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