On Wednesday (March 1) the drama that the two brightest planets, Venus and Jupiter have been engaged in for the past few weeks, reaches its pinnacle.
Venus and Jupiter have been slowly approaching each other, and this evening they will be closest together, appearing side-by-side about one-third up in the west-southwest sky at sunset. That favorably places them for viewing for at least two hours.
They will be separated in the night sky by a little over half a degree (0.53 degrees), or roughly the apparent width of the moon. Can you find them — first Venus, maybe with the naked eye, then both planets with optical aid — against the blue daytime sky before sunset?
No doubt these two brilliant luminaries will attract the attention of even casual people who rarely pay much attention to the night sky. They might even induce some to call local TV and radio stations or newspapers, or even police stations to report the "strange UFOs" hovering eerily in the evening twilight.
Maybe some will even mistake them for rogue balloons.
Venus and Jupiter in close contact
We did a check of Venus-Jupiter conjunctions over a 50-year interval (1990-2040) in which the two approached each other as close or closer as they will now, while maintaining a distance of at least 15 degrees from the sun, and found 15 such cases.
Tonight's conjunction will be the best for nearly a decade. Not until Feb. 7, 2032 will Venus and Jupiter come closer to each other (0.35 degrees), and that will be in the morning sky.
There is always a thrill in seeing two planets as globes in the same low-power or medium-power field of view — and this will be possible on Thursday (wider telescopic fields for this feat are needed the night before and the night after).
Of course, both planets are nearly at their smallest and will be low enough to appear rather shaky. Venus will appear as a small, gibbous-shaped blob. Jupiter will be noticeably larger, with three of its four Galilean satellites appearing in a nearly straight line on one side of the big planet; in this order moving outward: Io, Ganymede and Callisto.
For those living in the western US and Canada, the fourth Galilean moon — Europa — will appear to emerge from behind Jupiter on the same side as the other three at approximately 6 p.m. PST or 7 p.m. MST.
When both planets are viewed in the same telescopic field, whether in the afternoon or evening sky, Venus' disk has a far greater brilliance than Jupiter's.
These planets have approximately equal albedos, reflecting about three-fourths of the incident sunlight back into space. But Jupiter is nearly seven times as far from the sun as Venus, and receives barely two percent as much light per unit area as Venus does.
Hence, though Jupiter's disk appears nearly three times wider than Venus', the latter planet outshines Jupiter more than five times, their magnitudes being -3.9 and -2.1 respectively.
Just in case this current evening apparition of Venus seems a bit familiar to you, this year indeed marks a repetition. There is a rhythm in Venus' motion: In 8 of our years (2,922 days) Venus appears to go 5 times around our sky (its synodic period being 583.9 days). So, the difference between the two over a span of 8 years amounts to only 2.4 days.
Thus, Venus is now putting on nearly the same performance as in 2015. In May, Venus will lie above the highest point of the ecliptic, 44 degrees east of the sun and setting around midnight local daylight time for mid-northern latitudes.
For telescopic viewers, Venus will put on its best show from early June through early July, when it shrinks in phase from one-half to one-quarter illuminated, while its disk nearly doubles in size. By the beginning of August, Venus will disappear into the sunset fires, reappearing a few weeks later in the morning sky — where it will remain for the rest of 2023.
As for Jupiter, each year the largest of the planets travels 1/12 of the way around the sky around the sky, or generally one zodiacal constellation per year (because its sidereal period is 11.86 years).
On Jan.13 it began its six years in the northern celestial hemisphere, crossing the celestial equator about 3 degrees to the east of the point in the sky marking the vernal equinox. This is supposed to be Jupiter's "Aries year," though because of the irregular sizes and boundaries of the constellations, it actually started this year in Pisces.
Jupiter briefly clipped a corner of the non-zodiacal constellation Cetus between Feb. 5 and 18, before returning to Pisces until May 18. That's when it reaches into Aries, where it will stay for the balance of the year.
Jupiter remains in view in the evening sky until the end of March, then will disappear into the solar glare when it transitions into the morning sky. During early May, it will emerge from out of the glare of the rising sun and will become a fixture in the predawn sky through the remainder of the spring and into the summer and early fall. It will arrive at opposition on Nov. 3, when it returns to the evening sky for the rest of the year.
If you're looking to observe planets like Venus and Jupiter on your own and need help choosing gear, our best telescopes for beginners and best binoculars guides can help. You can also check out our guide on how to photograph the moon, as well as our best cameras for astrophotography and best lenses for astrophotography to learn how to capture your stargazing experience on camera.
Editor’s Note: If you snap a photo of the close approach of Venus and Jupiter and would like to share it with Space.com’s readers, send your image(s), comments, and your name and location to email@example.com.
Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, the Farmers' Almanac and other publications. Follow us on Twitter @Spacedotcom and on Facebook.