The Hubble Space Telescope and the European Space Agency’s Jupiter Icy Moons Explorer (Juice) have recently obtained striking new images of Comet 3I/ATLAS as it approaches its closest encounter with Earth this December. Discovered in July 2023, this comet is unique as it is the third interstellar object identified traveling through our solar system, having originated from beyond it.
Astronomers have turned their attention to 3I/ATLAS, conducting multiple missions to study its trajectory and composition. Observations, particularly during its proximity to the sun in October, have unveiled important details about the behavior and makeup of this fascinating celestial object. The Hubble Space Telescope played a crucial role in these studies, delivering detailed visuals of the comet’s teardrop shape shortly after its discovery in July. Its most recent observations, conducted on November 30 from a distance of 178 million miles (286 million kilometers), yielded clearer images thanks to its Wide Field Camera 3 instrument.
In tandem with Hubble’s observations, the Juice mission, which is destined to explore Jupiter and its icy moons, made an intriguing discovery during its voyage. Positioned approximately 41 million miles (66 million kilometers) from the comet, Juice utilized five scientific instruments and its Navigation Camera (NavCam) to capture significant activity surrounding 3I/ATLAS. The data included a glimpse of a glowing coma—an envelope of gas surrounding the comet—and two distinct tails: a plasma tail made of electrically charged gas and a faint dust tail consisting of solid particles released from the comet.
Comets like 3I/ATLAS typically develop such tails and a hazy coma as they near a star, indicating the sublimation of their material due to increased heat. The upcoming close approach of 3I/ATLAS on December 19 will bring the comet within 167 million miles (270 million kilometers) of Earth. Fortunately, it will be situated on the far side of the sun, posing no risk to our planet. For perspective, Earth orbits the sun at approximately 93 million miles (150 million kilometers).
The mesmerizing sight of Comet 3I/ATLAS will remain observable through telescopes and various space missions for several months before it continues its journey beyond our solar system. Following the closing data transmission expected between February 18 and February 20, additional insights—including images from high-resolution optical cameras and compositional data—are anticipated, further illuminating the comet’s origins and characteristics. As we explore the mysteries of the cosmos, the discoveries surrounding 3I/ATLAS continue to inspire scientific curiosity and enhance our understanding of interstellar phenomena.