A Week Of Exceptional Planetary Conjunctions

All in a row! Watch Mars slip between Saturn and Antares to form nearly a straight line on the evenings of August 23 and 24. Mars will be the brightest of the trio. Its rapid eastward motion will be obvious from one night to the next. Stellarium
All in a row! Watch Mars slip between Saturn and Antares to form nearly a straight line on the evenings of August 23 and 24. Mars will be the brightest of the trio. Its rapid eastward motion will be obvious from one night to the next. Stellarium

After a quiet weekend sky-wise, we’ve got a busy week ahead. On Tuesday night, Mars and Saturn will line up with Antares in Scorpius followed on Saturday by the closest conjunction of two naked-eye planets for the year.

On Saturday evening, August 27, Venus and Jupiter will approach within a hair’s breadth of each other as viewed with the naked eye — only 0.1° will separate them. That’s one-fifth of a full moon’s width! While Mars and Saturn will be easy to spot low in the southwestern sky during their conjunction, Venus and Jupiter “join hands” extremely low in the western sky about 30 minutes after sunset. Unless you deliberately look for them just a few finger widths above the due west point, they may elude your gaze.

Look for Venus and Jupiter right next to each other 4 degrees (about three fingers held together horizontally) above the western horizon not long after sunset. Map: Bob King; source: Stellarium
Look for Venus and Jupiter right next to each other 4 degrees (about three fingers held together horizontally) above the western horizon about a half-hour after sunset on August 27. Map: Bob King; source: Stellarium

Find a place in advance of the date with a wide open view to the west and bring binoculars to make the job of finding the two planets much easier. Venus will stand out right away. Once you’ve found it, look a smidge to its lower right for Jupiter. How do they look to your eye? I bet the view will be amazing, like looking at a bright double star in a telescope.

Here's what the two planets will look like through a telescope at medium and high magnification, when both will comfortably fit into the same field of view. Stellarium
Here’s what the two planets will look like through a telescope at medium and high magnification, when both will comfortably fit into the same field of view. Stellarium

Speaking of which, the planets are so close together that anyone with a telescope will be able to see them in the same high magnification field of view. Jupiter’s four brightest moons will be on display, and Venus will look just like a miniature version of the waxing gibbous moon. Rarely do the sky’s two brightest planets get this close.

If cloudy weather’s in the forecast that night, you can still spot the planets relatively close together the night before and night after, when they’ll be about 1° or two full moon diameters apart. I get pretty jazzed when bright objects approach closely in the sky, and I’m betting you do, too. But get this, the actual distance to Venus that evening is 143 million miles (230 million km) vs. 592 million miles (953 million km) for Jupiter. In spite of appearing to almost touch, Jupiter is more than four times farther than Venus. That distance translates to the chill realm of the giant gaseous planets where sunlight is weak and ice is common. Try stretching your imagination that evening to sense as best you can the vast gulf between the two worlds.