Look into the western sky this week to see an eye-catching conjunction between Mars and Regulus, the brightest star in the constellation of Leo, the lion. The chart shows the view from London at 2300 BST on 16 June 2025.
The pair of celestial objects will be separated by less than a degree, less than twice the apparent diameter of the full moon. This means that as well as being an easy spot with the naked eye, they are close enough to fit into the same field of view when viewed through binoculars. Although they will move further apart as the week continues.
The colour difference between them will be striking. Mars will be red whereas Regulus shines with a blue-white colour. Regulus is the 21st brightest star in the night sky and lies about 79 light years away from us. It contains just over four times the mass of the sun, and has a diameter just over four times larger, too, giving out about 340 times the sun’s energy.
From the southern hemisphere, too, the conjunction appears in the north-north-west. In addition, on 19 June, the moon will be close to Saturn in the constellation Pisces, the fishes.
