Let's take advantage of the first hours of the night, this weekend, to observe a beautiful conjunction of Jupiter and Saturn with the crescent moon. Venus will also shine splendidly at twilight in the west.
Jupiter continues on the border between the constellations of Aquarius and Capricorn, and is now the brightest Astro of heaven after the moon and Venus (which, as we describe below, looks in the west after sunset). To the right of Jupiter, as we look at the firmament, we can also observe Saturn, much weaker and more reddish.
Both gaseous giants are observable by Southeast after twilight, they are gaining height as the night progresses and hide at dawn in the West. In the middle of the night, they are about 50 degrees of elevation under unbeatable conditions for observation from Spain. In astronomical terms: the magnitude of Jupiter is now -2.8 and its apparent diameter measures 48 seconds of arc (about 40 times less than that of the full moon). The magnitude of Saturn is now 0.4 and its apparent diameter is 18 seconds of arc. This is equivalent to saying that Jupiter looks about 19 times brighter and has an apparent size 2.7 times greater than Saturn.
This weekend, the Gibosa moon, go to the appointment with the Giant Planets by offering us a beautiful conjunction. We can observe this scene very well since the sun goes down and there is enough darkness for the planets to contrast against the sky bottom. Friday 17 we were able to see our satellite between both planets, although a little lower over the horizon, while the moon days and the moon is already more and more to the left of Jupiter.
The gaseous giant is still close to its opposition, a position for which it happened a month ago. This means that Jupiter, the Earth and the Sun are still located almost on the same straight line. In this configuration it is in a position close to our planet, but, even so, its distance exceeds 600 million kilometers.
There are now another two planets that are observable to the naked eye. Venus can be seen shining splendidly in the west at twilight. These days are about 150 million kilometers away. This is 4 times closer than Jupiter, which makes it possible that, despite its much smaller size, Venus shows 2.3 times brighter than the giant planet.
The elusive mercury can see this weekend also in the sunsets, but next to the sun and very low on the horizon, which makes his observation require much more attention than Venus.
Mars is now coming next to the Sun Directorate and is not observable. It will be necessary to wait until the month of December to see him appear, at a very low elevations, Alba for the Southeast.
We are already very close to the Equinox, it is the period of the year in which the days shorten at higher speed. Every day that passes, the night wins 3 minutes a day. While the sky stays clear from clouds, it is a great time to follow the planets in their busy to happen between the stars, feel in contact with nature and admire the magic of Sublime Sky.
Rafael Bachiller is Director of the National Astronomical Observatory (National Geographic Institute) and academic of the Royal Academy of Doctors of Spain.Updated Date: 21 September 2021, 19:54