Jupiter, Venus, and Mercury are hundreds of millions of miles apart in the vastness of our solar system. But next week, the three planets are going to appear to be very close to each other in the evening sky at dusk.
The celestial show will reach peak brilliance on May 26 and 27, when the three planets will form a triangle in the western sky that will remain visible for about an hour after the sun sets.
The close gathering of three planets, known in astronomical terms as a triple conjunction, is somewhat rare. The last time three planets appeared this close to each other was in 2011. It won’t happen again until 2015, according to NASA.
This conjunction is particularly special because it includes the three brightest planets in the sky. It will also be the tightest grouping of three planets until January 2021.
How to watch
To catch the celestial show, go outside about 30 to 60 minutes after sunset and look west, NASA advises. Find Venus first, since it will be brightest, followed by Jupiter and Mercury.
Each planet will appear within roughly three degrees of each other in the evening sky. For comparison’s sake, if you make a fist and hold it up to the sky, that covers about 10 degrees of space. If you’re viewing the planets with binoculars, they should all fit inside the eyepiece.
The closeness of the arrangement of the three planets, and their brightness, will make this a once in a decade-type event, Dr. Alex Parker, a postdoctoral research fellow at the Harvard-Smithsonian centre for Astrophysics, told us via email.
The visual effect of a conjunction happens because the solar system’s planets lie in nearly the same plane, and each planet orbits at a different speed and distance from the sun, Parker said.
In this case, all three planets involved are currently on the far side of the sun from Earth. So while they appear close together in the sky, they’re actually far apart; for example, Jupiter and Mercury are separated by nearly 500 million miles, Parker said.
Interpreting planetary alignments
The planetary show might be misinterpreted by some people.
Thousands of years ago, planetary conjunctions like the one happening next week were events of major significance — though they weren’t always interpreted in a positive light.
“For the ancient Chinese, close gatherings of planets portended the end of — or at least a threat to — dynastic continuity,” Anthony Aveni, an astronomy and anthropology professor at Colgate University, and an expert in the field of astronomy, said in an email.
“The emperor would call his counsel and assess the threat, which makes sense because the planets look like they are conspiring in the sky.”
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