2023, July 12: Martian Summer, Morning Moon, Evening Planet Shuffle


July 12, 2023:  Summer begins on Mars today.  The morning crescent moon appears between Jupiter and Pleiades.  Venus and Mars dance with Regulus after sundown.

Photo Caption – 2007, December 1: Late winter in the northern hemisphere shows clouds above the northern polar cap and some above the southern cap. (NASA Photo)


by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 5:26 a.m. CDT; Sunset, 8:26 p.m. CDT.  Check local sources for sunrise and sunset times for your location.  Times are calculated by the U.S. Naval Observatory’s MICA computer program.

Vista From Mars Rover Looks Back Over Journey So Far Vera Rubin Ridge on Mars A viewpoint on “Vera Rubin Ridge” provided NASA’s Curiosity Mars rover this detailed look back over the area where it began its mission inside Gale Crater, plus more-distant features of the crater. The right-eye, telephoto-lens camera of the rover’s Mastcam took the component images Oct. 25, 2017. Image Credit: NASA/JPL-Caltech/MSSS

Summer begins in the Martian northern hemisphere today.  The seasons are from a tilt of 25°, similar to Earth’s.  Long duration Martian explorers would see the sun rising and setting at different locations along the horizon with a high summer sun and a low winter sun.

Photo Caption – Mars (NASA Photo)

The season lasts 183.46 Earth days or 178.56 Martian sols, the name for the day-night cycle on the Red Planet.  The sol is 24 hours, 39 minutes, 35 seconds.  Autumn arrives on Earth date January 12, 2024.

This self-portrait of NASA’s Curiosity Mars rover shows the vehicle on Vera Rubin Ridge, which it’s been investigating for the past several months. Poking up just behind Curiosity’s mast is Mount Sharp, photobombing the robot’s selfie. Image credit: NASA/JPL-Caltech/MSSS

Summer temperatures can rise to 70° F, but with very little atmosphere, and what little air exists, is primarily carbon dioxide. Dust storms can create reddish skies and sunsets.  Happy Martian Solstice!

Summaries of Current Sky Events

Here is today’s planet forecast:

Morning Sky

Chart Caption – 2023, July 12: Jupiter, Moon, and Pleiades appear in the east before sunrise.

The crescent moon this morning is between Jupiter and the Pleiades star cluster.  One hour before sunrise, the moon, 26% illuminated, is over 30° up in the east, 7.9° to the lower left of Jupiter. 

Look carefully for the Pleiades, nearly 12° to the lower left of the moon.  The cluster resembles a tiny dipper and may initially catch your eye when looking at the thinning crescent and bright Jupiter.  Tomorrow morning the crescent moon is near the cluster.

Photo Caption – 2022, September 23: Crescent moon with earthshine.

Look for earthshine on the night portion of the moon.  This is from sunlight reflected from Earth’s oceans, clouds and land that gently lights up the lunar night.

The Pleiades are part of Taurus.  The Bull’s brightest star, Aldebaran, is below the star cluster and nearly 15° above the horizon.

Photo Caption – Jupiter (NASA Photo)

Jupiter’s Great Red Spot is at the center of the planet in the southern hemisphere at 5:13 a.m. CDT, but it is visible across the Americas through a telescope earlier when it first enters the view from Jupiter’s rapid rotation.

Chart Caption – 2023, July 12: Saturn is in the southern sky during morning twilight.

Saturn, considerably dimmer than Jupiter, is nearly 40° above the southern horizon and west of the south cardinal direction. The planet continues to retrograde – appear to move westward against the distant stars – in front of dim Aquarius, nearly 13° to the upper left of Deneb Algedi, in Capricornus, and nearly 20° to the upper right of Fomalhaut, the mouth of the southern fish.

Evening Sky

Chart Caption – 2023, July 12: Venus, Mars, and Regulus are in the west after sundown.

Venus continues to sparkle in the western evening sky.  Still in its interval of greatest brightness, the planet’s visual intensity easily overwhelms all other starlike bodies in the sky.  The planet is easy to locate as night falls.

The Evening Star sets three to four minutes earlier each evening.  This evening it leaves the sky one hundred minutes after sundown.

Through a telescope, the planet is featureless from its veil of thick clouds.  It shows a crescent that is 22% illuminated.  The planet’s phases resemble Moon phases, but different terms are used from waxing and waning.  The cycle of phases appears differently from the moon’s phases.  To name them the shape and the time when the planet appears are used.  Tonight’s Venusian phase is evening crescent.

Venus continues to approach the star Regulus.  The gap is 3.8°, with the planet to the lower right of the star. Mars is 1.6° to the upper left of Regulus.  The trio is nearly in an imaginary line.  Venus closes to 3.5° in four nights in a near or quasi-conjunction.  Venus seems to be ducking under or south of Regulus, but there is no conjunction.  On the 22nd, Venus reverses its course and begins to retrograde. 

Chart Caption – 2023, July 12: Venus, Mars, and Regulus fit into a binocular during the early evening.

Use a binocular to initially locate Regulus and Mars.  Can you see them without the optical assist?

Venus is overtaking our planet on an inside orbital path that carries it around the sun every 225 days.  This evening it is 38 million miles away and closing in.  When Venus passes between Earth and the sun in a month, its distance is 27 million miles.

Mercury races into the evening sky to join Venus and Mars, although it is visible during brighter twilight.  On the 19th and 20th, Venus, Mercury, Mars, and the crescent moon create a planetary traffic jam in the western sky.

Each evening watch Mars march away from Venus and Regulus and the Evening Star slows as it nears retrograde.



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