May 23, 2022: The morning planets – Venus, Jupiter, Mars, and Saturn – and the moon appear as celestial stepping stones across the river of morning twilight.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 5:24 a.m. CDT; Sunset, 8:12 p.m. CDT. Check local sources for sunrise and sunset times for your location.
Notice that the length of daylight is approaching 15 hours at this latitude. Total twilight, before sunrise and after sunset, lasts four hours, four minutes. That leaves less than six hours for total darkness.
Twilight lengthens during the summer season in the northern hemisphere. The sun is farther north in the sky and takes longer to reach the angle at which the sky grows dark. Twilight occurs when the sun is within 18° of the horizon.
The four bright morning planets – Venus, Jupiter, Mars, and Saturn – and the moon are spaced across the eastern sky during morning twilight. The moon first attracts our attention. Only 43% illuminated, the lunar orb is 20° up in the southeast. Saturn is 15.9° to the upper right of the thick lunar crescent, while bright Jupiter is 22.4° to the moon’s left.
Look for dimmer Mars, 3.5° to the right of the Jovian Giant. Mars passes near Jupiter in a week. Watch the Red Planet get closer each morning.
Morning Star Venus is nearly 9° up in the east and 21.6° to the lower left of Jupiter. Venus is quickly stepping eastward away from the other three planets. The bright morning planets span 58.8 ° from Venus to Saturn.
The moon catches Venus in four mornings. A thin lunar crescent appears only 3.6° from the brightest planet.
Start at Venus and step to each planet and the moon as you would to cross a creek.
Mercury passed its inferior conjunction two days ago. It is moving into the morning sky, but it rises at about the same time as the sun.
Later next month, Mercury joins the current morning planet quartet along with the moon.
Step outside after nightfall. Two bright stars, Arcturus and Spica, are in the southern sky. Notice their contrasting colors. Arcturus is topaz in color, while Spica is sapphire. The contrast in star colors indicates they have different temperatures.
Arcturus is the second brightest star visible from the mid-northern latitudes and the brightest in the northern half of the sky, north of the celestial equator – the extension of Earth’s equator into the sky. The star is nearly 40 light years away from Earth, and it shines about 100 times brighter than our sun.
Spica is the 10th brightest star visible from northern latitudes. It is 250 light years away, shining with a brightness of nearly 2,000 stars equal to the brightness of our central star.
Contrary to artistic interpretations of color, blue is hotter than red-orange when comparing stellar characteristics.
Arcturus’ color indicates a temperature around 8,000°F, while Spica’s is about 40,000°F. Each square inch of the visible surface of Arcturus releases less energy than the sun and Spica. In comparison to Spica, a shovel full of Arcturus is darker than Spica’s surface.
Interestingly, Arcturus is a larger star than Spica. Arcturus is 12 times larger than the sun while Spica is 2.5 times bigger; that’s the diameter. The cooler and redder a star, the larger it must be to acquire significant brightness. Bright blue stars are not very large in comparison.
During this season, take a look at this stellar pair and note their contrasting colors.
- 2023, October 20: Jupiter’s Double Shadows, Mercury at Superior ConjunctionOctober 20: After midnight, Jupiter’s moons’ shadows dance across the cloud tops. Mercury is at superior conjunction.
- 2023, October 19: Poured Moon, See Planet UranusOctober 19: Sagittarius seems to pour the moon into the sky this evening. Find Uranus with a binocular.
- 2023, October 18: Moon-Antares Conjunction, Bright PlanetsOctober 18, 2023: The moon is near Antares after sunset. Venus, Jupiter, and Saturn are in the sky during the nighttime hours.
- 2023, October 17: Scorpion MoonOctober 17, 2023: The crescent moon is with Scorpius during evening twilight. Venus and Jupiter gleam from the predawn sky.
- 2023, October 16: Venus in Starry ConjunctionOctober 16, 2023: Venus passes a star in Leo before sunrise. A crescent moon is low in the western sky during evening twilight.