Seven Astronomical Events Not to Miss in 2021

Adriano Massatani is a member of the MAAS-affiliated astronomy society, the Sydney City Skywatchers. Here, he highlights seven events not-to-miss in 2021. While these are not the only astronomical events this year – the 2021 Australasian Sky Guide mentions more – these seven are particularly photogenic, and Adriano provides some suggestions for capturing them. Remember, of course, this is a southern hemisphere point of view.


1. Mercury and Jupiter just one Moon-width (or 0.5°) apart

Many people have never been able to see Mercury because it moves quickly across the sky and its low brightness is often overpowered by the brightness of the twilight sky. On Friday 5 March 2021, Mercury will be close to its greatest elongation (greatest angle from the Sun) and it will be only a Moon-width, or 0.5°, from Jupiter. The close couple will be best visible with a telescope with a low magnification and it can be captured with a planetary camera on the primary focus of your telescope. This event will be visible only in the morning before dawn. The best time is around 5:30 am (AEDT) when the planets will be 10° above the horizon. At that time you can also spot Saturn which is just a few degrees above Jupiter. The conjunction will be visible until 6:00am and then the planets will disappear in the brightness of the dawn. To capture the three planets, you can use your DSLR on a tripod and a standard camera lens. If you cannot make it on the 5th or clouds disturb the show, you can also observe it the day after.

Mercury and Jupiter (and Saturn)
Mercury and Jupiter (and Saturn) in the eastern sky at 5:30am AEDT on 2021 March 5. A full-frame camera at 85mm would capture all three planets and the horizon.
Mercury and Jupiter as they appear through a small telescope (magnification 50x) on 2020 March 05 at 5:30am AEDT. Made with Stellarium.
Mercury and Jupiter as they appear through a small telescope (magnification 50x) on 2021 March 5 at 5:30am AEDT. Made with Stellarium.


 2. Mercury, Jupiter and the Moon

These will be close enough to be captured in a 200mm lens. The Moon will be a thin crescent and a few seconds exposure with your DSLR will be sufficient to capture the planets and the Earthshine. There will be only one window of opportunity on Thursday 11 March between 5:30 and 6:00 am (AEDT). The trio will rise around 4:45 am (AEDT) and with some planning, you can create a breath-taking photo composition aligning some landscape features such as a distant building, a monument or a mountain with the planets and the Moon. Saturn will be a few degrees above Jupiter.

Three planets and the crescent Moon in the pre-dawn eastern sky on 2021 March 11 at 6:00am AEDT.
Three planets and the crescent Moon in the pre-dawn eastern sky on 2021 March 11 at 6:00am AEDT. A 200mm camera lens will capture Jupiter, Mercury and the Moon and, with careful framing, a distant foreground object.


3. Total Lunar Eclipse

This year we will have a Total Lunar Eclipse which, in Australia, will be visible just after dinner time from the East coast. Mark the 26 May on your calendar as you cannot miss this event; it will commence at 6:49pm (AEST). You will notice that the Moon will get dimmer as it enters Earth’s faint outer shadow (the umbra) at 7:46pm (AEST) and totality will be at 9:22pm (AEST). There are countless methods to capture a Lunar eclipse but a telescope with a long focal length (1000-1500mm) is preferred. During totality the moon is thousands of times dimmer than the fully illuminated moon so to attempt to capture the red colour during totality, and some stars, you need to increase the exposure time to a few seconds. A tracking mount is recommended. During the eclipse, the moon will be close to the star Antares and the Milky Way, and a wide field lens will be great to capture the red moon in a rich field of stars. Note, the timings here are from Sky Safari Pro.

[Please note that different apps, programs and websites may give slightly different timings by up to a few minutes.]

A total Lunar Eclipse during its totality. Credit & copyright: Adriano Massatani


4. Jupiter and Saturn at opposition

After the great conjunction of Jupiter and Saturn in December 2020, this year the two giants will appear close for the whole year and they will both be in opposition in August. Opposition occurs when a planet (one that is further from the Sun than Earth) is in line with Earth and the Sun – then the distance between us and the planet is a minimum and the planet is best seen. On 2 August 2021 Saturn will be at opposition displaying an apparent diameter of 18.6″ while the rings will stretch to 42.1″. Jupiter will be at opposition on 20 August with a diameter of 49.1″ and for anyone who is interested in Jupiter’s moons and how they interact, on August 16 Ganymede and Europa play hide-and-seek. First, Europa disappears into Ganymede’s shadow (an eclipse). Then, after it has reappeared for a few minutes Europa passes behind Ganymede and is hidden (an occultation). More information on this, and other hide-and-seek games the moons play, will appear in future blog posts.

Jupiter and Saturn close to their opposition in 2018. Credit & copyright: Adriano Massatani


5. Partial Lunar Eclipse, 97%

Another Lunar Eclipse will be visible on 19 November but this time it will not be total as the Moon will be covered only 97% by the Earth’s darkest shadow. The best time to observe this eclipse will be right after the sunset by looking at East, the totality will be at 8:06pm (AEDT) when the light of the dusk will still be bright. Later during the night, the sky will darken but the Moon will brighten up as it will leave the umbra at 9:49pm (AEDT).

Total Lunar Eclipse after totality. Credit & copyright: Adriano Massatani


6. Jupiter, Saturn, Venus and the Moon

Jupiter, Saturn and Venus will all be aligned and only a few degrees apart offering a rare chance to capture a spectacular wide field shot. The date to remember is December 7 with the Moon and Venus very close. The best time to capture this conjunction is at 9:15 pm (AEDT) or a bit earlier if you want to capture the colour of the dusk. If you miss the show on the 7th, the Moon passes Saturn on the 8th and Jupiter on the 9th. And on the 10th all four objects are lined up nicely!

Conjunctions between Moon-Venus (top) and Moon-Venus-Jupiter (bottom) from Yulara, NT, 20 June 2015. Credit & copyright: Adriano Massatani


7. Geminids Meteor Shower 

Meteor showers can frequently disappoint the observer due to their low rate (of meteors) per hour. In the Southern Hemisphere, the Geminids are well visible and under a dark sky, they can surpass a rate of 50 meteors per hour. According to the International Meteor Organization, in 2021 the peak will be on December 14 at 5 pm (AEDT), so during the afternoon and during daylight. Considering that the Moon will be almost full, the best time to observe the Geminids will be between 2:30 am and 4:30 am on 14 and 15 December. Meteor showers occur when the Earth transits across an area with more dust and particles (left behind by a comet) which gets attracted by the Earth’s gravity. The particles enter our atmosphere at high speed, decelerate rapidly causing the air around them to glow (making the “shooting star” or meteor that you see) and often vaporise completely. The morning hours before dawn are the best moment to watch a meteor shower as the Earth is facing the “cloud” of dust during its orbit around the Sun. By analogy, there is a higher chance to hit an insect on the front windscreen of your car rather than on the side windows.

A clear night and camera equipment set up ready for a promising night ahead. Credit & copyright: Adriano Massatani.
A clear night and camera equipment set up ready for a promising night ahead. Credit & copyright: Adriano Massatani.

3 responses to “Seven Astronomical Events Not to Miss in 2021

Leave a Reply