A lunar occultation of the planet Saturn was visible from the UK in the early hours of 21 August 2024.
This marked a great chance to see one of the most inspiring sights in planetary observing, as Saturn disappeared behind the Moon from our perspective on Earth, only to reappear 45 minutes later.
Find out more about how to calculate and observe lunar occultations and how to observe Saturn
Lunar occultations explained
A lunar occultation occurs when the Moon’s disc appears to cover a more distant object, hiding it from view.
Although the Moon looks impressive and dominant in a dark sky, its apparent size is actually only half a degree across.
The Moon is able to move around the sky in a relatively narrow corridor approximately 10° wide, centred on the ecliptic.
The main planets also stay near the ecliptic, but the width of the Moon’s corridor means planetary occultations are infrequent.
There are three types of lunar occultation event: disappearance, reappearance and a graze.
The third type is a special kind of occultation where, from your position, the Moon’s edge appears to scrape the more distant object.
In the case of a planet with a tangible apparent size, it only gets partially hidden by the Moon.
Saturn lunar occultation dates and times
The lunar occultation of Saturn on 21 August was a full occultation from the UK.
Disappearance occured at 04:28 BST (03:28 UT) at the start of dawn.
The sky was fairly dark at this time, making Saturn easy to monitor as the Moon approaches.
The lunar occultation of Saturn was visible seen with the naked eye, although the Moon’s brightness can make Saturn harder to see close to the lunar limb.
Binoculars will show a lunar occultation well, but a telescope will really bring home what’s happening.
It took 49 seconds for the Moon’s edge to fully cover the planet.
Saturn reappeared 45 minutes later, at 05:13 BST (04:13 UT), from behind the Moon’s dark edge.
Observing the occultation
At the time of the occultation, Saturn appeared quite edge-on to us, its northern pole tilted toward us by just 3°.
Consequently, the planet’s rings appeared rather thin, something most apparent if using
a smaller scope.
Another interesting observation to carry out during the event is the planet’s brighter moons being occulted.
Brightening skies may make them harder to see, but Saturn’s largest moon, Titan, should be easy to keep track of during disappearance and just visible at reappearance.
The Moon is close to Earth and exhibits parallax, appearing in a slightly different position relative to the background stars depending on your location.
Did you observe or photograph the lunar occultation of Saturn on 21 August 2024? Let us know by emailing contactus@skyatnightmagazine.com.
