After sunset this week – October 10, 11 and 12, 2018 – look for the young moon and king planet Jupiter in the western twilight sky. Especially from the Northern Hemisphere – where the autumn ecliptic now slants low in the evening sky – the whisker-thin evening crescent might be a challenge to spot at dusk on October 10. Day by day, for all of us around the globe, the waxing crescent will widen and brighten and stay out longer after sunset. It’ll be easier to see the moon when it pairs up with Jupiter on October 11 and then climbs above Jupiter on October 12.
Binoculars and an unobstructed horizon in the direction of sunset may come in handy for catching the moon and Jupiter after sunset (especially at northerly latitudes).
In the northern tropics and the Southern Hemisphere, you’ll have an easier time of spotting the moon (and Jupiter), because these two worlds stay out longer after sunset than at northerly latitudes. In fact, from southerly latitudes, you have a much better chance of spotting Venus, the sky’s brightest planet, beneath the moon and Jupiter this week. Venus is now heading into the sun’s glare. It’ll pass between us and the sun on October 26, 2018. Between now and then, telescopic viewers can see Venus as a waning crescent.
The moon and Jupiter should be easy to spot on October 11 and 12, assuming your sky is clear. Venus will be tougher – lower in the sky – more deeply buried in the sun’s glare. If you want to see Venus, especially if you’re in the Northern Hemisphere, find an unobstructed sunset horizon and bring along your binoculars.
The setting times for the sun, moon, Jupiter and Venus vary worldwide. If you live in the United States or Canada, click here to find out when they all set. Elsewhere around the world, click here to find out when the sun and moon set in your sky, and click here to find out when Venus and Jupiter set in your sky. (Remember: these setting times presume a level horizon.)
Although the sky chart at the top of this post is for about 40 degrees north latitude in North America, the position of the planet Jupiter and the star Antares will be virtually the same at evening dusk at 40 degrees north latitude around the world. But on the same date, at 40 degrees north latitude in the world’s Eastern Hemisphere, look for the moon’s position relative to Jupiter and Antares to be offset toward the previous date.
The sky chart below is for 40 degrees south latitude in South America (Valdivia, Chile). As in the Northern Hemisphere, the positions of Venus, Jupiter and Antares are alike at the same latitude, but as seen from the world’s Eastern Hemisphere, the moon’s position relative to Jupiter, Venus and Antares is offset toward the previous date.
By the way, two other planets light up the sky at dusk and nightfall: Mars and Saturn. As seen from northerly latitudes, Mars – the brighter of these two worlds – sits rather low the southern sky at dusk/nightfall (roughly the same spot as the winter noonday sun). And as seen from southerly latitudes, at dusk and nightfall, Mars appears much higher up in the sky (about where you’d see the summer noonday sun).
Once you spot Mars, look for Saturn between Mars and Jupiter.
Mars and Saturn stay out well beyond nightfall now, but the same can’t be said for the moon and Jupiter (especially at northerly latitudes). Look for the moon and Jupiter (and possibly Venus) to pop out in the west in the darkening evening twilight.
Bottom line: Shortly after sunset on October 10, 11 and 12, 2018, seek for the young moon and king planet Jupiter in the western twilight dusk.
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.