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Starts With A Bang

How To Watch Mercury, Venus, And The Moon All Unite In This Week’s Skies

Conjunctions of Mercury and Venus, where they both meet in the sky, can be the best opportunity for spotting the elusive innermost planet. This photo, taken on January 10, 2015, showcases a very close approach of the two planets in the post-sunset skies. We’ll get a very similar phenomenon on May 21/22. (Alan Dyer /VW PICS/Universal Images Group via Getty Images)

Find a clear western horizon after sunset, and this ‘triple treat’ of a dance can be yours.


Every once in a while, the night sky provides a spectacular feast for our eyes.

It only happens once every 11 years, but occasionally, all five naked-eye planets are visible at once. Mercury is always the toughest to spot due to its proximity to the Sun, but occasions where an even brighter object is nearby (like Venus) can make it much easier to spot. (MARTIN DOLAN)

The planets and moons, all moving at relatively different speeds, constantly change their positions.

The seven extraterrestrial planets of the solar system: Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune. Photographed in 2019 with a Maksutov telescope from Mannheim and Stockach in Germany. The angular sizes and colors shown are accurate, but the brightnesses are not: Venus is some 63,000 times brighter than Neptune, or 12 astronomical magnitudes; the same difference as between the full Moon and a typical bright star like Vega or Capella. (GETTY IMAGES)

From May 21 through May 25, Mercury, Venus, and our Moon will all dance together in Earth’s post-sunset skies.

This animation shows the relative positions of Venus, Mercury, and the Moon in the post-sunset skies from approximately 45 degrees north latitude from May 14, 2020 through May 25, 2020. (E. SIEGEL / STELLARIUM)

Mercury is currently emerging from behind the Sun, while Venus is swinging between the Sun and Earth.

The relative configuration of the planets in our Solar System on May 18, 2020. The directions-of-motion have been added in to illustrate how Mercury, Venus, Earth, and Earth’s Moon are moving relative to one another at the present time. (HTTPS://WWW.THEPLANETSTODAY.COM/, ANNOTATIONS BY E. SIEGEL)

In our skies, Venus now approaches the post-sunset horizon while Mercury gets farther from it.

Depending on where in the world you are, Mercury and Venus will make their closest approach to one another in the post-sunset skies on either May 21 or May 22, 2020. If you have a pair of binoculars and can identify Venus, Mercury should appear in the same field-of-view. (E. SIEGEL / STELLARIUM)

On the nights of May 21 and May 22, they will almost coincide, passing within 0.9° of one another.

The phases of Venus, as viewed from Earth, can enable us to understand how Venus appears to move east-to-west from the perspective of Earth. As Earth and Venus both orbit the Sun, Venus does so at a faster pace, which means that as it emerges (in a counterclockwise orbit) from behind the Sun, it will appear to move away from the Sun and higher in the post-sunset skies. If you view Venus in the skies right now, in late May, 2020, you’ll find it in a thin crescent phase. (WIKIMEDIA COMMONS USERS NICHALP AND SAGREDO)

Venus’s thin crescent phase should be clearly visible through a pair of binoculars.

Through either binoculars or a telescope, Venus will no longer look like a single point of light, but will be readily visible in a thin crescent phase. Be prepared for how surprisingly bright such a thin crescent will appear; it outshines Mercury by about a factor of ~100 in brightness at the moment. (E. SIEGEL / STELLARIUM)

Nearby, in that same field-of-view, Mercury should also be readily apparent.

The fields-of-view of various types of binoculars are shown with various red circles. Through practically any pair of binoculars, however, if you can find Venus, looking closer to the horizon and slightly farther to the south should reveal Mercury as well. (E. SIEGEL / STELLARIUM)

Over the next few nights, Venus descends and Mercury continues rising, with both joined by the waxing Moon.

The relative configuration of the Moon, Mercury, and Venus on May 24, 2020. Note that the Moon and Mercury will appear very close to one another in the sky, and that Mercury will be slightly more well-separated from the Sun while Venus will be closer to it compared to 6 days prior. (HTTPS://WWW.THEPLANETSTODAY.COM/)

On May 23, Venus and the Moon will make a close approach, visible shortly after sunset.

The Moon and Venus will make their closest approach to one another on May 23, 2020, with Mercury still hanging out nearby. Mercury continues to ascend while the Moon rises, but Venus continues its journey closer to the Sun. (E. SIEGEL / STELLARIUM)

The next night, May 24, sees the Moon make a close pass by Mercury, with Venus still close by.

Although the Moon will vastly outshine Mercury, those of you who wait until May 24 to go look for our Solar System’s innermost planet will find that the Moon, Mercury, and Venus all make a relatively straight line. If you can find the Moon and Venus, they will guide you towards Mercury. (E. SIEGEL / STELLARIUM)

Mercury continues its ascent until June 4, but its brush with Venus and the Moon is your best viewing opportunity.

When looking at an interior planet, it will never appear to ‘wander’ too far from the Sun. As Mercury approaches its greatest elongation in the post-sunset skies, it’s generally useful to have a marker nearby to help in finding it, something that Venus and the Moon can provide.

Travel the Universe with astrophysicist Ethan Siegel. Subscribers will get the newsletter every Saturday. All aboard!

WIKIMEDIA COMMONS USER WMHERIC


Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.

Ethan Siegel is the author of Beyond the Galaxy and Treknology. You can pre-order his third book, currently in development: the Encyclopaedia Cosmologica.

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