Comet Tsuchinshan-ATLAS Breaking Up Before Close Approach to Earth


Comet C/2023 A3 (Tsuchinshan–ATLAS) was set to light up the night sky as it made a close approach to Earth on October 12, coming within 70.6 million kilometers (43.9 million miles) of our planet.

Some even predicted it would be brighter than Jupiter and visible at sunset, a rare and thrilling event for skywatchers and astronomers alike.

However, recent analysis by astronomer Zdenek Sekanina suggests that the comet is likely to break apart before this close encounter.

Though his findings are not yet peer-reviewed, Sekanina points out that the comet shows signs of disintegration as it heads towards its closest approach to the Sun on September 27, at a distance of 58.6 million kilometers (36.4 million miles).

This disintegration is a common fate for many comets as they near the Sun and experience intense solar heating.

The Process of Outgassing

As comets get closer to the Sun, they heat up and start to lose gas and dust, forming their distinctive tails.

This process, known as outgassing, can change the comet’s speed, rotation, and path—something called “non-gravitational acceleration.”

Essentially, the gases act like tiny thrusters, altering the comet’s trajectory.

While the comet has shown unexpected acceleration due to these forces, it hasn’t brightened as expected, which is unusual.

Issues Highlighted by Sekanina

Sekanina highlights two key issues in his analysis.

First, the comet hasn’t brightened at a heliocentric distance greater than 2 AU (Astronomical Units), which is about 160 days before reaching its closest point to the Sun (perihelion).

This lack of brightening is accompanied by a sharp drop in dust production.

Typically, as comets move within 2 AU of the Sun, they develop noticeable plasma tails from ionized gas.

However, Tsuchinshan-ATLAS’s tail is unusually thin and primarily composed of dust, resembling tails of comets from the Oort cloud, a distant region of the solar system.

These Oort cloud comets often disintegrate during close approaches to the Sun, which doesn’t bode well for Tsuchinshan-ATLAS.

Predictions and Opportunities

Given its current state, Sekanina predicts that Comet Tsuchinshan-ATLAS will disintegrate before it gets too close to the Sun, around 0.39 AU.

This is disappointing for those hoping to see the comet in all its glory, but it provides a valuable opportunity for astronomers to study the disintegration process of Oort cloud comets.

Observing how these comets break apart can offer insights into their composition and structure, which are otherwise difficult to study.

Emission of Large Grains

Interestingly, Sekanina suggests that the comet is emitting large grains of material far from the Sun.

These grains are causing acceleration without creating a visible coma (the nebulous envelope around the nucleus of a comet).

These large “blobs” of material are particularly intriguing because they might resemble the behavior of the interstellar object ‘Oumuamua, which passed through our solar system in 2017.

Unlike typical comet dust, these blobs do not break down into smaller particles, remaining as large, dark, and porous fragments.

Continued Observation

Astronomers will continue to monitor the comet’s journey closely.

There’s still a slim chance it might not break apart and could indeed light up the sky as initially hoped.

Regardless of its fate, the comet’s journey provides a unique scientific opportunity.

If it disintegrates, we gain insights into the life cycle of such comets; if it survives, we witness a spectacular celestial event.

Either way, the journey of Comet Tsuchinshan-ATLAS is bound to be a fascinating chapter in our understanding of these icy wanderers of the solar system.