Four bright planets parade across the July morning sky.
by Jeffrey L. Hunt
Venus, Mars, Jupiter, and Saturn stretch across the sky during morning twilight.
Brilliant Venus puts on a display low in the east-northeast sky as it approaches the Hyades star cluster in the constellation Taurus. In the image above notice that the planet is 0.6° to the upper right of the star named Delta 1 Tauri (δ1 Tau on the photo).
Look each morning at the same time to see Venus higher in the sky and farther into the cluster. The best morning is July 8, when Venus is in the middle of the cluster.
Follow the progress of Venus among the stars with a binocular.
At the same time, Venus is 3.7° to the upper right of the brighter star Aldebaran.
Mars is in the southeast, moving eastward in Pisces. It is 3.6° from 29 Piscium (29 Psc). Each morning the planet moves farther from that star. Use a binocular to see Mars with the background stars.
Beginning in early September, Mars stops moving eastward compared to the starry background and begins moving westward compared to the stars (retrograde motion). This occurs when our faster moving planet approaches and moves past the slower moving outer planets.
On October 13, Earth moves between Mars and the sun. Known as opposition, the sun and Mars appear at opposite parts of the sky. At opposition, Mars rises in the eastern sky, when the sun sets in the western sky. The planet is in the south at midnight and sets in the west when the sun rises in the east.
Around opposition Mars is closest to our planet. Because Mars’ orbit is more elongated, the “closest approach” occurs a few days before or after opposition. This year, Earth and Mars are closest a week before opposition.
Meanwhile, Jupiter and Saturn are retrograding in the south-southwest. Saturn is 3.1° to the lower right of the star Sigma Capricorni (σ Cap), while Jupiter is 2.2° below the star 56 Sagittarii (56 Sag).
Jupiter is at opposition on July 14, followed by Saturn 6 days later. The planets continue to retrograde until September. When they resume their eastward motion relative to the stars, Jupiter overtakes and passes Saturn in a once-in-a-generation Great Conjunction on December 21, 2020. This is the closest conjunction of the planets since 1623.
Jupiter and Saturn can be seen in the evening sky about 2 hours after sunset, in the east-southeast.
Mercury joins the parade beginning July 19 when the “Classic 9” planets are in the sky simultaneously along with the moon.
For more about the planets see this article about where to find them during July.