July 31, 2023: Venus, Mercury, and Mars are quickly sliding into brighter sunlight. Mars ends its two-year appearance.
by Jeffrey L. Hunt Chicago, Illinois:
Sunrise, 5:43 a.m. CDT; Sunset, 8:10 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.
The month ends with fourteen hours, twenty-seven minutes of daylight. It lost forty-four minutes.
Summaries of Current Sky Events
Here is today’s planet forecast:
Morning Sky
On this last morning of the month, two bright planets are easily visible before sunrise. Bright Jupiter is over halfway up in the east-southeast at one hour before daybeak. It is moving eastward in front of Aries, 12.5° to the lower left of Hamal, the pattern’s brightest star, and 11.4° to the upper left of Menkar, Cetus’ nostril.
At this level of twilight in Chicago, Jupiter’s Great Red Spot is visible in the planet’s clouds. It is visible in the center of the planet at 5:15 a.m. CDT, about 30 minutes before sunrise in Chicago. The atmospheric feature is visible in a darker sky for sky watchers farther westward.
Before moonlight washes across the sky at this hour beginning tomorrow morning, use a binocular to look at the Pleiades star cluster to the lower left of Jupiter. The star cluster resembles a miniature dipper. The bright reddish star Aldebaran, Taurus’ brightest, is nearly 14° to the lower right of the Pleiades.
The Bull’s eye and the Hyades star cluster make a sideways “V” forming the animal’s head. Point the binocular at this as well.
Saturn, after its nightly westward journey, is about 30° above the southwest horizon. It is retrograding, appearing to move westward compared to the starry background, in front of Aquarius, 7.3° to the upper right of Skat, the Aquarian’s leg, and 6.3° to the lower right of Lambda Aquarii (λ Aqr on the chart). The background stars are dim and washed out by outdoor lighting. Use a binocular to see Saturn farther westward each morning against the sidereal background.
Evening Sky
Venus is skedaddling from the evening sky. At sunset, it is less than 4° above the western horizon, and still visible with a careful look. It sets about twenty minutes later. Venus passes between Earth and the sun on August 13th, known as inferior conjunction, and seemingly skips into the morning sky. In a month, it stands about 10° above the eastern horizon at one hour before daybreak.
Mercury, nine nights before its greatest elongation, is dimming each evening. It is less than 4° above the west-northwest horizon at forty-five minutes after sundown. Mercury aficionados can follow it for a few more evenings from an observing spot with a clear horizon.
Mars, dimmer than Mercury, is over 5° above the west horizon at one hour after sundown. This is goodbye to the Red Planet after its two-year run that took it through Taurus during its opposition and into the western sky. This evening Mars sets 95 minutes after the sun, before the end of evening twilight.
The Red Planet returns to the morning sky after it passes its solar conjunction on November 18th. It then appears west of the sun, rising before the central star. It appears in the morning sky during January 2024. Mercury passes by on January 27th and Venus on February 22nd. The moon, 99% illuminated, is low in the east-southeast as night begins. It sets in the southwest before sunrise tomorrow. The moon is at its Full moon phase before it rises tomorrow evening.
Saturn rises earlier each evening, now over seventy minutes after sundown. By three hours after nightfall and before midnight in most regions of time zones, it is about 20° up in the southeast and over 35° to the lower left of the moon.
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