Jupiter and Saturn lead Mars and Venus during late July’s morning planet parade.
by Jeffrey L. Hunt
Four planets – Jupiter, Saturn, Mars, and Venus – are strung along an arc in the morning sky. They appear along the solar system’s plane that astronomers call the ecliptic. During the pre-sunrise hours of late July, the imaginary line stretches from the southwest skyline to the east-northeast horizon.
Bright Jupiter and Saturn are low in the southwest in front of the stars of eastern Sagittarius. They are moving westward – retrograding – compared to the starry background. While they rise in the east before sunset and appear low in the southeast during evening hours from Earth’s rotation, they are moving westward compared to the distant stars. This westward movement compared to the stars is an illusion when Earth overtakes, passes, and moves away from them.
Jupiter and Saturn are 7.5° apart. In another month, they are about another degree apart.
In September, Jupiter and Saturn begin moving eastward again. Jupiter inches toward Saturn and passes it in a Great Conjunction, December 21, 2020. This is the closest conjunction of the two planets since 1623. A Jupiter – Saturn conjunction occurs every 19.6 years.
Through a binocular check their positions each clear morning compared to the stars. Jupiter is 0.6° to the left of 50 Sagittarii (50 Sgr), while Saturn is 3.3° to the upper left of 56 Sagittarii (56 Sgr). Watch Jupiter pass 50 Sgr and Saturn approach 56 Sgr.
Farther east, Mars is that “bright star” in the southeast. It is among the dim stars of Pisces. On the photo above, it is moving into the starfield where it retrogrades and passes opposition (October 13, 2020). This morning the Red Planet is 5.1° to the upper left of 20 Ceti (20 Cet) and 5.0° below Epsilon Piscium (ε Psc). As with Jupiter and Saturn, watch Mars move eastward in the starfield through a binocular.
The brilliant Morning Star Venus is in the eastern sky. It is moving eastward among the stars of Taurus. This morning it is 4.3° to the upper right of Zeta Tauri (ζ Tau), the Southern Horn of the Bull. The bright star Aldebaran, the Bull’s Eye, and two star clusters (Hyades and Pleiades) appear above the bright planet.