September 2, 2023: The moon approaches Jupiter before sunrise and again after sunset. Venus appears in the east during morning twilight near Procyon and Sirius.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 6:17 a.m. CDT; Sunset, 7:23 p.m. CDT. Check local sources for sunrise and sunset times. Times are calculated by the US Naval Observatory’s MICA computer program.
The five-planet morning parade continues with Venus, Jupiter, and Saturn easily visible. Uranus is easy to locate through a binocular between Jupiter and the Pleiades star cluster. The challenging view, even through a binocular, is locating Neptune in a dim Pisces starfield, over 20° to the upper left of Saturn. For sky watchers interested in seeing the two more distant planets, see the directions in the August 27th article.
Summaries of Current Sky Events
Here is today’s planet forecast:
Morning Sky
One hour before sunrise, the bright gibbous moon, 92% illuminated, is nearly 40° up in the southwest and over 30° to the lower right of Jupiter.
The Jovian Giant is slowing its eastward gait to appear to reverse its direction in two nights. Earth is overtaking Jupiter on an inner orbital path, passing between the sun and Jupiter during November. This morning the planet is 13.6° to the lower left of Hamal, Aries’ brightest star, and over 16° to the lower right of the Pleiades star cluster, part of Taurus. Use a binocular to see the stellar bundle in this moonlight.
This morning, the moon is more than halfway from Jupiter to Saturn that is about 5° above the west-southwest horizon. This is one of the last mornings that the Ringed Wonder is visible at this time interval before sunrise. It is not as bright as Venus or Jupiter. Once it is below about 5° above the horizon, the earth’s atmosphere blurs, dims and reddens stars and planets, giving the sun and moon their flattened shapes and distinctly orangish colors when rising or setting.
Saturn is easily observed earlier during the night. Find it in the east-southeast after sunset and then farther westward during the night.
Venus continues its grand entrance in the eastern sky. The brilliant Morning Star is about 10° up in the east at this time interval before sunrise. It is over 40° to the lower left of Sirius, night’s brightest star, that is nearly 15° up in the southeast.
Venus does not pass closely to Sirius. The star is too far from the plane of the solar system, known as the ecliptic, where the planets seem to move. No planetary body in our solar system appears near the star.
Beginning in about a week, Venus and Sirius are about the same altitude – height above the horizon during morning twilight. This occurs each morning throughout the month.
Notice Procyon, the Little Dog Star, above a line from Venus to Sirius.
Evening Sky
Mercury and Mars are hiding in bright evening twilight. Mercury is four days from inferior conjunction, between Earth and Sun. Then it moves into the predawn sky for its best morning appearance of the year.
Mars is dimmer than might be expected and awash in evening twilight. It sets about an hour after sunset. It is on a very slow slide toward its solar conjunction during November.
An hour after sundown, Saturn is about 10° up in the east-southeast. Look an hour later when the background stars are easier to see. Then the planet is over 20° above the southeast horizon.
Saturn is retrograding in front of Aquarius, 8.7° from Skat, meaning “the leg,” and Lambda Aquarii (λ Aqr on the chart), making an equilateral triangle.
At this time, the bright moon, 87% illuminated, is low in the eastern sky. An hour later, three hours after sunset, the gibbous moon is higher in the east, while Jupiter is nearly 5° above the east-northeast horizon.
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