We have finally entered the month of September, however if you were to tell me that it was the 200th Day of March, I would honestly believe you. 2020 has been such a bizarre year, one we will never forget, but one thing we can take comfort in, is the fact that the night sky will always keep changing as we move through the months.
In terms of great cosmological phenomena, there is not much to report in September, however there is something interesting happening with the most mysterious planet in the solar system on 11th September.
Neptune will be at opposition and this means that it will be at its closest approach to Earth and its face will be fully illuminated by the Sun! It will be brighter than any other time of the year and will be visible all night long. This is the best time to view and photograph Neptune. The only issue with this though is that Neptune is extremely far away from the Earth. Neptune sits at 30AU from the Sun, whereas the Earth is only 1AU from the Sun. Due to this distance, Neptune will only appear as a tiny blue dot in all but the most powerful telescopes.
As we move through the month, we come up to a New Moon on 17th September. This is a great time for stargazers to look into the sky, as the stars and astronomical objects will not be obscured by the moonlight, and even some deep sky objects will be visible if you have the right equipment.
Looking South, Jupiter, Saturn and Mars will be visible in the sky around 11 o’clock at night. The two large gas giants, Jupiter and Saturn, will be lower down on the horizon and this will be your last chance to see them at this time, before they disappear. They will be close to each other in the night sky, with Jupiter, the larger planet, being bigger and brighter. The best way to tell planets apart from stars is the fact that planets don’t twinkle in the sky like stars do.
Mars will appear red in the sky. This redness is cause by the rust on the surface of the planet, leftover from ancient oceans of water, that disappeared as Mars’ atmosphere started to thin. If you can use a pair of binoculars, or even a telescope, you might be able to see very faint features on the surface of Mars. In the 19th century, observers thought they could see evidence of canals on the surface of Mars. These canals were first described by the Italian astronomer Giovanni Schiaparelli during the opposition of 1877. Astronomers back then were convinced that this showed evidence of an ancient Martian Alien population, but as our technology developed in the early 20th century, observations revealed the “canals” to be an optical illusion.
The constellation of Pegasus, the winged horse, will also be visible in the southern sky, and this particular star pattern is often seen as one of the heralds of Autumn.
Pegasus is famed for having the Giant Square that makes up the belly of the beast. Made up of four bright stars, the Great Square of Pegasus is relatively simple to find in the night sky. The four stars are called Alpheratz, Scheat, Markab and Algenib. However, this square is strange in that it is not actually a square at all. The star Alpheratz now belongs to the next constellation over, Andromeda the Princess. The International Astronomical Union made this switch back in the early 20th Century.
Late September will also be an excellent time to get some glimpses of the International Space Station, at a reasonable time of night! The ISS is the largest man-made object ever constructed, and typically six astronauts are always onboard. After the Sun and the Moon, the ISS is one of the brightest objects that can be seen in the sky. Check out the table below to see when is best to put on your coat and go outside for a look.
Finally on the 22nd September we have the September Equinox! Yes, it is that time of the year again! Astronomically speaking, we will be in the first day of Autumn. In the Southern Hemisphere this equinox sees the start of their spring. The September equinox occurs the instant the Sun crosses the celestial equator – the imaginary line in the sky above the Earth’s equator – from north to south. This happens either on September 22nd, 23rd, or 24th every year.
That’s it for this month, stargazers! Enjoy the skies and stay safe.