Observing Challenge — See A Slim Crescent, Venus, Mercury And Jupiter At Dusk

This will be the scene tomorrow evening (Thurs. August 5) facing west 30 minutes after sunset from the central U.S. The glowing spot of sunset is off to the right. Jupiter stands about one fist held vertically above the western horizon. The moon, Mercury and Venus just a few degrees high (two fingers atop each other at arm's length). Use binoculars to help you spots the four. Credit: Bob King , source: Stellarium
This will be the scene tomorrow evening (Thurs. August 4) facing west 30 minutes after sunset from the central U.S. The glowing spot of sunset is off to the right of Venus. Jupiter stands about one fist held vertically above the western horizon. The moon, Mercury and Venus are just a few degrees high or two fingers. Use binoculars to help you spot the four. Credit: Bob King , source: Stellarium

Every so often in this blog we feature an observing challenge. Since the summer weather’s so nice and you have a little free time after dinner, why not grab your binoculars and head out to the nearest western horizon shortly after sunset. If the air is transparent with no haze or clouds obstructing the view, tomorrow night (August 4) look for the super-thin lunar crescent sharing space with no fewer than three planets: Jupiter, Mercury and Venus.

The crescent moon continues to add sparkle to the scene when it passes just 1 degree below Jupiter on the following night, Friday August 5. Stellarium
The crescent moon continues to add sparkle to the scene when it passes just 1 degree below Jupiter on the following night, Friday August 5. Stellarium

Start watching no later than a half hour after sunset. The moon will be very low but should still be the easiest to see of the four celestial objects. Jupiter’s next in difficulty followed by Mercury and Venus. Whenever I’m digging for planets in bright twilight, I make sure to have binoculars handy. If you can spy just one of the four, you can “star-hop” from there to the other three by pointing your binoculars left or right, up or down. The map will help guide you there.

The pleasures of skywatching continue the following evening when the slightly thicker crescent will be in conjunction with Jupiter just 1° below the planet. With or without optical aide, this should be a pretty sight.

As the sky gets darker, Mars, Saturn and the bright star Antares in Scorpius grab your eye. If you succeed in the observing challenge, you will have spotted all the naked eye planets in one evening! Stellarium
As the sky gets darker, Mars, Saturn and the bright star Antares in Scorpius form a nice, compact triangle at nightfall in the south-southwestern sky.  If you succeed in this week’s observing challenge, you will have spotted all five naked eye planets in one evening — congratulations! Stellarium

Lest we forget the other bright planets out this month, make a quarter turn to your left either evening to face south-southwest. Right in front of your eyes about one-third of the way up from the southern horizon to the zenith, Saturn and Mars light up the constellation Scorpius the scorpion. Because they’re farther from the sun in the sky, we can wait until darkness to see them. The best time to view them is from about 9:30 to 11 p.m. local time.