On the morning of 10 April, a bright 83%-lit waning gibbous Moon occults mag. +2.9 Alniyat (Sigma (σ) Scorpii).
The event, known as a lunar occultation, starts around 03:33 BST (02:33 UT) when the Moon sits 11° above the southern horizon as seen from central UK, the Moon’s southwest limb hiding the star.
Reappearance occurs when the Moon is due south, Alniyat reappearing from the Moon’s dark southeast limb at 04:30 BST (03:30 UT).
Read our beginner's guide and find out how to observe a lunar occultation.
The times above are given for the centre of the UK and may vary by a few minutes depending on location, so it's worth observing the event early to capture the full spectacle.
Observing lunar occultations of bright stars is rewarding. Watching the star through an eyepiece before disappearance helps you appreciate how fast the Moon’s apparent motion is in the sky.
A lunar occultation of a star happens quickly. Lose concentration or blink at the wrong time and the airless Moon and point source star will disappear from view in a lost instant.
You should aim to start observing from 03:00 BST (02:00 UT)
Reappearance is just as quick, compounded by the doubt that you may not be looking at precisely the correct part of the Moon’s limb to see it.
Alniyat is one of the two stars that flank the bright-red supergiant Antares (Alpha (α) Scorpii). Shining at mag. +1.0, Antares sits 2° to the east-southeast of Alniyat.
Did you manage to observe or photograph the lunar occultation of Alniyat? Let us know by emailing contactus@skyatnightmagazine.com.
This guide originally appeared in the April 2023 issue of BBC Sky at Night Magazine.
