This summer, evening sky observers have been treated to two solar system planets, Jupiter and Saturn.
Both planets are still well placed in the southwestern evening sky. Jupiter is the brighter of the two while Saturn is just to the east.
Saturn’s orbit like Mars, Jupiter, Uranus and Neptune lies beyond the Earth’s orbit. Since the Earth’s orbit is smaller Earth moves faster around the Sun than the outer planets. Earth takes 365 days to orbit the Sun while Mars takes 687 days, Jupiter 12 years, and Saturn 29 years.
This evening we focus on the planet Saturn, the sixth planet and the planet famous for its beautiful ring system.
The word “planet” is a Greek word that means wanderer. Planets wander or orbit the Sun against the background stars.
Since May 11 Saturn has been moving west as seen from Earth. Because the Earth moves faster, Saturn will appear to stop this evening September 29th. From now on Saturn will resume its easterly movement.
For a time Saturn is ahead of the Earth and appears to move west, then the Earth catches up to Saturn, and for a day or so Saturn appears to be stationary. As the Earth passes Saturn, Saturn resumes it eastward movement around the Sun. This is an optical illusion due to the faster movement of the Earth as it catches up and passes Saturn, it appears Saturn has stopped even though it is still moving around the sun.
No wonder the ancients called these objects “wanderers” of the night sky
