A few days ago, an inscrutable interstellar interloper made its closest approach to Mars, where a fleet of international spacecraft seek to unravel the red planet's ancient mysteries.
Several of the probes encircling Mars took a break from their usual activities and turned their cameras toward space to catch a glimpse of an object named 3I/ATLAS, a rogue comet that arrived in our Solar System from interstellar space and is now barreling toward perihelion—its closest approach to the Sun—at the end of this month.
This is the third interstellar object astronomers have detected within our Solar System, following 1I/ʻOumuamua and 2I/Borisov discovered in 2017 and 2019. Scientists think interstellar objects routinely transit among the planets, but telescopes have only recently had the ability to find one. For example, the telescope that discovered Oumuamua only came online in 2010.
