An interstellar comet, designated 3I/ATLAS, has just completed its closest approach to the sun, coming within approximately 126 million miles (or 203 million kilometers) of our star. This passage marks a significant moment, as the comet continues on an outgoing trajectory, but it remains within our solar system for now. Astronomers expect to observe the comet again in a few weeks, following its brief disappearance from sight.
According to Darryl Seligman, an assistant professor in the department of physics and astronomy at Michigan State University, stargazers will likely catch a glimpse of 3I/ATLAS in the predawn sky starting November 11. Observations will continue until the comet departs our solar system, with its closest approach to Earth set for December 19, when it will come within about 168 million miles (or 270 million kilometers) of our planet. Notably, this interstellar visitor poses no threat to Earth, as confirmed by the European Space Agency (ESA).
Discovered on July 1, 3I/ATLAS is only the third known interstellar object to traverse our solar system. Each observation contributes valuable data, helping scientists understand how this comet differs from those originating from within our own cosmic neighborhood. Comets are often described as “dirty snowballs,” comprising a solid core of ice, dust, and rock. As they approach stars, they heat up, releasing gas and dust that form their distinctive tails.
The interest in 3I/ATLAS stems from its potential to reveal insights into its composition and the star system from which it originated. Seligman notes, “When it gets closest to the sun, you get the most holistic view of the nucleus possible.” Understanding the composition of the comet’s volatiles can provide scientists with a glimpse into the primordial material from which it formed.
To study 3I/ATLAS, astronomers have employed advanced tools like the Hubble Space Telescope and the James Webb Space Telescope. Observations from these instruments, along with missions such as SPHEREx, have detected various substances, including carbon dioxide, water, carbon monoxide, and carbonyl sulphide. Preliminary estimates suggest that the comet is between 3 billion and 11 billion years old, which is significant when considering that our solar system is about 4.6 billion years old.
The comet has recently faded from the view of ground-based telescopes, but it remains visible to some space missions, including PUNCH (Polarimeter to Unify the Corona and Heliosphere) and SOHO (Solar and Heliospheric Observatory). On October 3, 3I/ATLAS made its closest approach to Mars, coming within 18.6 million miles (or 30 million kilometers) of the planet. Although a government shutdown has hindered data sharing from NASA missions observing the comet since October 1, the ESA’s Mars Express and ExoMars Trace Gas Orbiter have attempted to capture images of the comet, with the latter managing to observe it as a faint dot.
As the comet continues its journey, the ESA’s Jupiter Icy Moons Explorer (Juice) will also attempt observations in November, though data will not be available until February due to transmission delays. Seligman emphasizes that astronomers have several more months to study 3I/ATLAS, promising exciting scientific discoveries ahead.
With each observation, scientists hope to uncover more about this interstellar visitor, enhancing our understanding of comets and the broader cosmos.
