Weymouth Astronomy

The Planets - September 2021


Mercury might just be spotted very low in the west at the very start of the month having a magnitude of -0.05. Binoculars may well be needed, but please be careful and not use them before the Sun has set.


At the start of September Venus, at magnitude -4.04 will only have an elevation of 10 degrees at sunset looking towards the southwest. Venus will present in the evening sky for the rest of this year and reaches its greatest elongation east from the Sun on October 29th but will be highest in the evening sky at the beginning of December.


Mars starts the month with a magnitude of +1.79 and an angular size of 3.57 arc seconds. It may then just be possible to spot it after sunset, down to the right of Venus.


As the month begins Jupiter can be seen throughout the night shining at magnitude -2.85 and having an angular size of 48.83 arc seconds. By month's end its magnitude will have reduced slightly to -2.72.


Saturn precedes Jupiter into the sky, rising before sunset at the beginning of the month and setting at 3 am. During the middle of the month it will be best seen towards the south at 22:29 BST when it will have an elevation of just 19 degrees.

Information collated from Jodrell Bank and Astronomy Now magazine