On August 23, 2018 – as soon as darkness falls – enjoy the beautiful moon and planet Mars ascending in your eastern sky. They can be viewed from all over the world, except at the far-northern Arctic latitudes. These two worlds – the moon and Mars – rank as the brightest and third-brightest celestial luminaries to light up the nighttime sky, respectively. Venus is second-brightest, and you’ll find it in the west after sunset. Jupiter is fourth-brightest, and it’s not far from Venus now, in the west as darkness falls.
You should have little or no trouble spotting the moon and Mars, even before nightfall, or at evening dusk. After you see them, turn around and look at Venus and Jupiter! Wow. That’s a lot of brightness – more than we typically see at once – in our night sky.
Best of all, the moon and Mars stay out for most of the night, whereas Venus sets a few hours after the sun. From around the world, the stately couple climbs highest up for the night at roughly 10 p.m. local time (11 p.m. local daylight saving time) and then sets in the west in the wee hours before dawn. If you want to know more specifically when the moon and Mars transit – or climb highest up for the night – and then set, click on this U.S. Naval Observatory page.
If you haven’t seen Mars yet – or even if you have – let the moon guide your eye to Mars on August 23. Be sure to get an eyeful of Mars while it’s still in its moment of glory. We passed between Mars and the sun on July 27. It’ll remain bright through late August.
Right now, Earth, in its faster orbit around the sun, is leaving Mars farther and farther behind; and as a consequence, Mars will slowly but surely dim in the months ahead. One month from now, in September, Mars will be about half as bright as it is now; and two months from now, in October, Mars will be about one quarter of its present brightness.
Enjoy Mars now! You won’t see it exhibiting 2018’s super brightness again for about 15 years.
Despite this rapid decline in brilliance, we’re happy to report that Mars will still be as bright as a 1st-magnitude star by the year’s end. Some four months from now, in December 2018, Mars’ brightness will be about the same as that of the planet Saturn at present (August 2018). However, Saturn’s change in brightness is not that dramatic. In fact, one year from now – in August 2019 – Saturn will be virtually the same brightness that it is now, yet Mars will be about 40 times fainter.
Bottom line: On August 23, 2018, the bright waxing gibbous moon pairs up with the brilliant red planet Mars, and the spectacular twosome lights up the nighttime from dusk until the wee hours of the morning.
Bruce McClure has served as lead writer for EarthSky's popular Tonight pages since 2004. He's a sundial aficionado, whose love for the heavens has taken him to Lake Titicaca in Bolivia and sailing in the North Atlantic, where he earned his celestial navigation certificate through the School of Ocean Sailing and Navigation. He also writes and hosts public astronomy programs and planetarium programs in and around his home in upstate New York.