The year’s closest conjunction of planets comes this Saturday – and they are the two brightest.
Venus will pass north of Jupiter by only 0.07° (2.3 times Jupiter’s apparent width), so they will be like a single star. Their magnitudes of -3.9 and -1.7 add up, in the logarithmic way of magnitudes, to -4, not quite as brilliant as Venus can be by itself when farther out from the Sun. The “appulse,” or closest moment, is August 27 about 22 Universal Time, which is 6 PM by clocks in eastern North America, 3 PM on the Pacific coast – a couple of hours before the time of this twilight picture.
The planets are 22° out east from the Sun, but unfortunately for us in the northern hemisphere they are out along the southward-sloping late-summer reach of the ecliptic, therefore at a low angle to our horizon. At the time pictured, they are only about 2 degrees above the horizon, and soon to set. Possibly you can spot them sooner, or even by daylight. At only 10 minutes after sunset, they will be more like 8° high.
Mercury is nearby, and will at Aug. 28, 4 UT, form a tightest grouping with the other two, a “trio,” the three fitting in a circle of minimum diameter barely over 5°. But Mercury, unlike the other two, happens to be well south of the ecliptic, thus hopelessly out of view for northern observers.
For those living on the southern hemisphere of our rounded planet, the scene is tilted much more favorably.
The season here is late winter and the ecliptic slopes steeply upward from Sun to planets. At this place and time, Venus and Jupiter are 12° above the horizon, Mercury 15°.
This is how the planets are moving in space.
Their courses are shown for the month of August, with sightlines from Earth at Aug. 28.0. The dashed line is the vernal equinox direction, the origin or “Greenwich” for our mapping of space.