Interstellar Comet 3I/ATLAS Shows Increased Activity Ahead of December Flyby

New images from NASA and the European Space Agency (ESA) reveal that interstellar comet 3I/ATLAS is exhibiting significant activity as it approaches Earth for a flyby on December 19, 2023. The comet, currently about 270 million kilometres away, has spent months traversing the inner Solar System, and its recent interactions with the Sun appear to have intensified gas and dust emissions.

The latest observations, captured by the Hubble Space Telescope, provide one of the clearest views of 3I/ATLAS to date. The image displays a bright nucleus encircled by an expanding coma, indicating that material is sublimating into space. NASA explained that as comets heat up, they become brighter, and the jet-like features visible in the recent images suggest that the comet’s surface is responding actively to solar radiation.

Astronomers first identified 3I/ATLAS as an interstellar visitor earlier this year. NASA’s detailed report outlined the comet’s size, speed, and unusual composition, noting that its nucleus measures between 440 metres and 5.6 kilometres wide. This size classifies it among the largest interstellar objects detected so far.

Unique Perspectives from Spacecraft

ESA’s Juice spacecraft, which is en route to Jupiter’s moons, also captured remarkable images of 3I/ATLAS from just 66 million kilometres away. The photograph reveals a glowing halo and two distinct tails, supporting the idea that the comet is undergoing rapid changes. Juice obtained this image shortly after the comet’s closest approach to the Sun, providing valuable insights into its behaviour as it heated up.

Both Hubble and Juice are part of a growing network of spacecraft observing 3I/ATLAS. Various observatories across the Solar System are collecting complementary data, each set of images contributing to our understanding of the materials formed outside our planetary system. Scientists consider this a rare opportunity, as 3I/ATLAS is estimated to be nearly 10 billion years old.

The comet will be visible to skilled observers during its flyby. A telescope with a minimum aperture of 30 centimetres is recommended for viewing due to its magnitude. For those interested, guidance on locating 3I/ATLAS in the night sky indicates that it will be positioned beneath the star Regulus in the constellation Leo during its closest approach, which is best viewed before dawn.

Scientific Insights and Future Trajectory

While astronomers emphasize that 3I/ATLAS poses no risk during its close pass, they view the event as an opportunity to study how interstellar objects react to extreme heating as they travel through our Solar System. The James Webb Space Telescope is also expected to observe the comet in the coming weeks, and both professional and amateur astronomers will continue to gather data from Earth. These observations will help refine predictions for the comet’s future trajectory.

After passing Earth, 3I/ATLAS will head toward Jupiter, where a close encounter in March 2026 could alter its path. The extent of this change will depend on how much material the comet continues to eject following its recent surge in activity. This December represents the only occasion when 3I/ATLAS will come this close to Earth, offering scientists a final chance to study this extraordinary visitor from beyond our Solar System.