<p><img src="https://static5.businessinsider.com/image/5ffc8dcbd184b30018aae16c-1194/IMG_20201218_181731_043.jpg" border="0" alt="jupiter saturn conjunction" data-mce-source="Gary Hershorn" data-mce-caption="An image of Saturn (above) and Jupiter (below) in the sky above a church in New York City, December 2020." data-link="https://twitter.com/GaryHershorn"></p><p></p><bi-shortcode id="summary-shortcode" data-type="summary-shortcode" class="mceNonEditable" contenteditable="false">Summary List Placement</bi-shortcode><p>Mercury, Jupiter, and Saturn are currently clustering together in the night sky.</p><p>Monday is <a href="https://solarsystem.nasa.gov/whats-up-skywatching-tips-from-nasa/">the final night</a> that the three planets will be lined up and visible at twilight. They appeared the closest they'd been in more than two decades on Sunday, forming an equilateral triangle.</p><p>"This shape is just a blip in time," Amy Oliver, a spokeswoman for the Harvard-Smithsonian Center for Astrophysics, <a href="https://www.bostonglobe.com/2021/01/09/metro/planets-align-form-rare-trio-this-weekend/#:~:text=The%20last%20planetary%20trio%20was,Saturn%20will%20come%20close%20together.">told the Boston Globe</a>. "We won't see it exactly like this ever again, since it probably isn't going to happen again in this exact same wayat least not in your lifetime."</p><p>An astronomical event in which celestial bodies align like this is called a conjunction. A triple alignment like this is known as a planetary trio.</p><p>If you hold your palm up to the sky and all three planets cluster within a circle that fits in the space between your ring finger and your pointer finger, that's a trio. </p><p>Here's how to see the planetary trio before it's gone.</p><h2>Head out at twilight, and bring binoculars</h2><p><img src="https://static3.businessinsider.com/image/5ffc8e3cd184b30018aae16f-2400/GettyImages-56650267.jpg" border="0" alt="mercury" data-mce-source="Space Frontiers/Hulton Archive/Getty" data-mce-caption="The surface of Mercury, as photographed by the Mariner 10 craft, 1974."></p><p>On Monday, head out at twilight, between half an hour and 45 minutes after sunset. Look to the southwestern sky. The clearer the sky is, and the father from city lights you are, the easier it will be to see the conjunction. </p><p>Jupiter will look brightest to the naked eye (it's about 10 times bright than Saturn), followed by Mercury, then Saturn. </p><p>Since Saturn is so dim, it may not be distinguishable from the sun's afterglow with the naked eye. So the best way to spot the planetary triangle is to focus your eyes on Jupiter, which will be near the top, then point a pair of binoculars at it. Mercury and Saturn should appear in the same binocular field as Jupiter, <a href="https://earthsky.org/tonight/planetary-trio-low-in-west-at-dusk#link=%7B%22role%22:%22standard%22,%22href%22:%22https://earthsky.org/tonight/planetary-trio-low-in-west-at-dusk%22,%22target%22:%22_blank%22,%22absolute%22:%22%22,%22linkText%22:%22EarthSky%22%7D">according to EarthSky</a>. </p><p>After Monday, Jupiter and Saturn will dip below the horizon and no longer be visible, while Mercury will continue rising in the sky night after nightmoving steadily away from the other two planets.</p><p>Although the three worlds seem to almost touch during the planetary trio, Jupiter and Saturn are actually separated by <a href="https://www.planetsforkids.org/closest-planet-to-saturn.html" data-analytics-module="body_link" data-analytics-post-depth="40" data-uri="9898ea70ce945ed9e4893c082154308c">almost five times</a> the distance between Earth and the sun. Mercury and Saturn are separated by nearly twice that distance. </p><h2>The last time these 3 planets aligned so closely was in 2000</h2><p><img src="https://static3.businessinsider.com/image/5ffc8f17d184b30018aae174-2400/GettyImages-90730878.jpg" border="0" alt="saturn" data-mce-source="SSPL/Getty" data-mce-caption="A photo of Saturns and two of its moons, taken by Voyager 1 in 1980."></p><p><a href="https://www.businessinsider.com/photos-jupiter-saturn-align-conjunction-2020-12">Astronomers turned their telescopes skyward</a> last month to catch another conjunction event, when <a href="https://www.businessinsider.com/see-jupiter-and-saturn-align-rare-double-planet-conjunction-2020-11">Jupiter and Saturn aligned</a> more closely than they had for centuries.</p><p>In the last 2,000 years, there were just two times that Jupiter and Saturn came closer in the sky: One was in 1623, but the sun's glare made it impossible to see. The other was in 1226. </p><p>Planetary trios, by contrast, are far more common. The last one was in October 2015. Another trio, involving Mercury, Venus, and Jupiter, will happen on February 13, <a href="https://earthsky.org/tonight/planetary-trio-low-in-west-at-dusk#link=%7B%22role%22:%22standard%22,%22href%22:%22https://earthsky.org/tonight/planetary-trio-low-in-west-at-dusk%22,%22target%22:%22_blank%22,%22absolute%22:%22%22,%22linkText%22:%22EarthSky%22%7D">according to EarthSky</a>.</p><p>The last time Mercury, Jupiter, and Saturn formed a triangle was <a href="https://nssdc.gsfc.nasa.gov/planetary/alignment.html">in May 2000</a>.</p><p><strong>SEE ALSO: <a href="https://www.businessinsider.com/photos-jupiter-saturn-align-conjunction-2020-12" >Photos reveal Jupiter and Saturn aligned in the sky as a 'Christmas star' that hadn't been seen for 800 years</a></strong></p><p><a href="https://www.businessinsider.com/how-see-conjunction-mercury-jupiter-saturn-planetary-trio-2021-1#comments">Join the conversation about this story »</a></p> <p>NOW WATCH: <a href="https://www.businessinsider.com/saturn-losing-rings-faster-than-thought-nasa-2018-12">Saturn is officially losing its ringsand they're disappearing much faster than scientists had anticipated</a></p> Click here to read full news..