A Rare Astronomical Phenomenon of Three Planets Aligning Occurs This Week

Early Tuesday morning, an extraordinary site began to unfold in the dark sky visible to the naked eye. Three planets, Jupiter, Saturn, and Mercury, aligned their orbits, creating the optical effect of appearing side by side, reports Passant Rabie for Inverse. The "planetary trio" will also be in conjunction with a waning crescent moon for three successive mornings until Thursday, March 11, reports Jamie Carter for Forbes. The alignment gives us a rare peek at Mercury.

Planetary conjunction occurs when multiple planetary orbits line up. Though it appears as if they are next to each other in the sky, the distance between the planets remains the same, reports Megan Marples and Ashley Strickland for CNN. These rare events often happen many years apart. Jupiter and Saturn are in conjunction once every 20 years, NASA reports in a statement. In December 2020, Jupiter and Saturn appeared so close to each other that they resembled a giant star in the sky in what's known as the "Great Conjunction," Inverse reports. The last time this happened was 400 years ago.

Mercury, the smallest planet in our solar system, is difficult to spot with the naked eye because of its size and proximity to the sun. It is often only visible at specific times of the year, after sunset or in early twilight, reports Inverse.

Jupiter and Mercury were in peak conjunction on March 5, CNN reports. Soon after peak, Mercury reached its greatest maximum elongation from the sun on March 6, Inverse reports. While the two planets' conjunction already passed, Mercury will still be visible during the alignments of the "planetary trio" in the east-southeastern horizon until early Thursday morning on March 11. During the three planets' alignment, Jupiter and Mercury will be 0.3 degrees apart, with Saturn to the two planets' right at 8 degrees above the horizon, Inverse reports.

Although the planets seem like they are close in proximity and we can see them in the Earthly skies, they are actually extremely far away. Mercury is 89 million miles away from Earth, Jupiter is 551 million miles away and Saturn is the furthest at almost a billion miles from Earth. The closest object in proximity to Earth is the moon at 239,700 miles away, reports Joe Rao for Space.com.

After the planetary alignment, Jupiter and Saturn will be visible in the early morning Eastern sky for the rest of March, Bruce McClure and Deborah Bryd report for EarthSky. Mercury will continue to be seen as a bright star until March 20, CNN reports.

Elizabeth Gamillo | | READ MORE

Elizabeth Gamillo is a daily correspondent for Smithsonian and a science journalist based in Milwaukee, Wisconsin. She has written for Science magazine as their 2018 AAAS Diverse Voices in Science Journalism Intern.