During the year, most the activity of the bright planets occurs in the evening sky. Mercury makes three evening appearances. During the first, it passes Jupiter and Saturn after the Great Conjunction. Venus appears in the western, although it sets before the end of twilight until later in the year. The brilliant planet has conjunctions with Mercury and Mars.
Several groupings occur with the moon and they are indicated on the chart.
Take note of the grouping of moon with the moon and planets in the western sky during June and July.
A challenging attempt to see five planets and the moon occurs on August 18. Mercury appears in a difficult-to-observe apparition and has a conjunction with Mars. Venus is higher in the sky while Jupiter and Saturn are in the eastern sky. The moon is present as well.
Mars leaves the evening sky later during the summer. The year ends with four planets – Mercury, Venus, Jupiter, and Saturn in western sky.
The chart above shows setting of the naked-eye planets, moon, and bright stars near the ecliptic for 2021. The graphs display the rising of these celestial bodies compared to sunrise and sunset for time intervals up to five hours before the sun’s appearance. The three phases of twilight are displayed as well. On the setting chart, activity occurs in the western sky, except for the rising curves (circles) of Jupiter and Saturn.
It should be noted that when two objects set at the same time intervals after sunset (same clock time), they are not necessarily near each other. It merely means that they rise or set at the same time interval after sunset. Since the charts feature objects’ activities near the ecliptic, they are likely to be up to 10° apart.
The charts are calculated from data by the U.S. Naval Observatory, for Chicago, Illinois.
August 1 – 6, 2021: The morning moon wanes toward its New moon phase in the eastern sky. It passes the bright stars that are prominent in the evening sky during the winter season in the northern hemisphere. The stars have been making their first appearances in the morning sky during summer. At this hour, Procyon and bright Sirius are the last stellar duo to appear.
August 6, 2021: In the northern hemisphere, summer’s midpoint occurs today at 6:27 p.m. CDT.
July 31, 2021: The slightly gibbous moon, nearing its Last Quarter phase, is in the southeast as morning twilight begins. It is near the planet Uranus, easily within reach of a binocular. Mira, a variable star, reaches its brightest next month.
July 29, 2021: In a challenging-to-see conjunction, Mars passes 0.6° to the upper right of the star Regulus.
July 27, 2021: Evening Star Venus, Mars, Saturn and Jupiter are in the evening sky. Mars is nearing its conjunction with Regulus in two evenings.