From 12 June onwards, if you catch Mars in the sky during the darkening evening twilight, you'll see the planet pass closer and closer to bright star Regulus each night.
Regulus is the brightest star in the constellation Leo, often known as the 'lion's heart'.
It's also at the bottom of the Sickle star pattern, which looks rather like a backwards question mark.
Regulus sits close to the ecliptic, the Sun’s apparent path across the sky, which represents the projection of the Earth’s orbital plane into space.
The ecliptic and Regulus conjunctions
We need to go all the way back to the formation of the Solar System to explain the ecliptic.
The Solar System planets all formed out of the same dusty disc surrounding our newborn star.
As a result, all the Solar System planets appear in Earth's sky on or around the same path that the Sun traces across our sky.
And because Regulus happens to be located in the same patch of sky as the ecliptic, it often appears close to planets in our night sky, in events known as conjunctions.
Of course, these apparent meetings are a matter of perspective. The planets of our Solar System orbit the Sun, our host star, while Regulus is a distant star all of its own.
This upcoming meeting of Mars and Regulus in our night sky is an opportunity to observe this chance alignment.
The Red Planet will get closer and closer to Regulus each night, eventually passing just north of it.
Observing the Mars Regulus conjunction
The Sky at Night's Pete Lawrence reveals key timings for the event:
The best time to see Mars and Regulus will be in the darkening evening twilight from 23:00 BST (22:00 UT) between 15 and 18 June, when both objects are visible about 15° above the western horizon.
At the time of their meeting, Mars will be shining at mag. +1.4, a fraction dimmer than Regulus’s mag. +1.3.
On the evening of 15 June, the two objects are separated by 1.2°.
On 16 June, the gap closes to 52 arcminutes, dropping to 45 arcminutes on 17 June.
Close though this will appear, remember you could still fit 1.5 full Moons between them.
On the evening of 18 June, the gap reopens, with Mars and Regulus now separated by 1°.
Finally, on the evening of 29 June, a 22%-lit waxing crescent Moon invades the show.
Mars will have moved significantly further east on this date, now sitting 7° from Regulus. The Moon will sit between the two planets, 2° to the west of Mars.
See if you can find Mars and Regulus with the naked eye, then grab a pair of binoculars and get a closer look.
Remember to wait until the Sun has fully set before doing so, as catching a glimpse of the setting Sun through binoculars could damage your eyesight.
If you do happen to catch – or even photograph – this meeting of Mars and Regulus, be sure to share your images with us via contactus@skyatnightmagazine.com
