How, When And Where To See The Solar System’s Biggest And Smallest Planets ‘Collide’ After Sunset

Next week Jupiter and Mercury will appear to pass very closely in the post-sunset night sky.

It won’t be a fair fight between the biggest and smallest planets in the solar system. Jupiter has 5,750 times more mass than Mercury, according to Universe Today. Jupiter is a ball of gas while Mercury is made of rock. Jupiter is the fifth planet from the Sun while Mercury is the closest, though it’s no longer the Sun’s nearest neighbor.

However, while giant Jupiter is sinking into the Sun’s glare—soon to appear in the predawn night sky—tiny Mercury is on the cusp of reaching its highest position in 2023 above the horizon after sunset. Despite that, this planetary conjunction will take place in bright evening twilight, so does present some challenges.

Here’s everything you need to know to see a rare conjunction of Jupiter and Mercury with your naked eyes:

When is the conjunction of Jupiter and Mercury?

The conjunction of Jupiter and Mercury will occur on Monday, March 27, 2023 in the constellation Pisces. However, you should also look on the nights either side to appreciate the sight of one planet sinking while one is rising.

What is a conjunction?

A conjunction is an astronomical event that occurs when two celestial objects appear to be close together in the sky. That could be two planets—as with Jupiter and Mercury this week—a planet and a star or object, or a planet and the Moon.

How to see the conjunction of Jupiter and Mercury

Next week Mercury and Jupiter will appear to swap positions, with the tiny planet rising while the giant planet sinks in our sky. The swap occurs on the evening of Monday, March 27, 2023. The best views will be afforded to anyone who points a pair of binoculars to the western sky about 30 minutes after sunset, but a low view of the western horizon will be essential because the conjunction will be visible only about 4° up. They easily fit into the same binocular field of view, according to When The Curves Line Up.

Despite their different sizes both planets with appear to shine about the same brightness, with Jupiter at magnitude -2 and Mercury at magnitude -1.4.

How close will Jupiter and Mercury actually be?

Jupiter and Mercury will appear to be just 1.3° from each other in the sky on Monday, March 27, 2023. However, in reality they will be about 840 million miles from each other. A conjunction is merely a line-of-sight event of no scientific significance. Go look at The Planets Today : A live view of the solar system and you’ll see that as Earth orbits the sun our view of the planets—all of which are all orbiting the sun at different speeds—changes significantly. It’s not unusual for two planets to appear close together in our night sky despite them not actually being physically close at all.

Best time to see Mercury

If you want to see Mercury at its brightest—and highest in the post-sunset twilight sky—return after sunset on Tuesday, April 11, 2023 when it will reach its greatest eastern elongation (its apparent farthest from the Sun) and its highest point above the western horizon in the early evening sky. On that same date, Jupiter will pass the sun’s far side in an event called solar conjunction, according to In The Sky, before emerging into the pre-dawn sky a few weeks later.

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Mercury: the diamond planet?

Last year it was suggested by planetary scientists that the heavily cratered planet could be hosting an astonishing 16 quadrillion tons of diamonds. Apparently, Mercury is covered in graphite, a pure form of carbon that may have been transformed into diamonds after the planet was struck by meteorites, asteroids and comets.

BepiColumbo at Mercury

An upcoming mission from the European Space Agency called BepiColumbo will map Mercury at different wavelengths once it arrives on December 5, 2025. The spacecraft’s two orbiters—the ESA Mercury Planetary Orbiter (MPO) and the JAXA Mercury Magnetospheric Orbiter (MMO)—will together study Mercury’s origin and evolution, its interior structure, geology, composition and craters, its atmosphere and magnetosphere (and how it interacts with the solar wind), and the origin of Mercury’s magnetic field. It will also examine deposits at its poles.

Wishing you clear skies and wide eyes.