The largest known comet, Bernardinelli-Bernstein, is on a journey through our solar system, offering scientists a unique chance to study its composition.
Get ready for a celestial visitor! The colossal Comet Bernardinelli-Bernstein, estimated to be between 120 and 137 kilometers (75 to 85 miles) in diameter, is heading towards the inner solar system. This “dirty snowball,” originating from the distant Oort Cloud, is the largest comet ever detected. It’s expected to reach its closest point to the sun, known as perihelion, around January 29, 2031.
Astronomers are buzzing about this icy giant. Using the Atacama Large Millimeter/Submillimeter Array (ALMA) with its 66 interconnected radio telescopes, researchers observed the comet in March 2024. They detected jets of gas erupting from its surface, a sign that the comet is warming up as it approaches the sun. These observations, published in The Astrophysical Journal Letters, are providing unprecedented insights into how these massive icy bodies function.
“These measurements allow us to see how this huge ice world works,” said astrochemist Nathan Roth from American University and NASA Goddard Space Flight Center. “We observe the explosive formulas of the gas departure, raising new questions about how this comet will evolve when it continues on its way inside the solar system.”
On March 8, 2024, ALMA detected two jets spewing from the comet’s solid ice core, primarily composed of carbon monoxide. The team also identified the beginnings of a “coma,” a faint atmosphere of dust and gas that surrounds comets and can form their characteristic tails. By March 17, 2024, only one jet was visible, suggesting the comet’s activity had decreased as it moved away from its peak activity.
While previous observations, including those by the Hubble Space Telescope, had hinted at a coma, this marks the first detection of gas emissions from Comet Bernardinelli-Bernstein. What’s particularly remarkable is that these emissions were observed when the comet was still far from the sun, about 16 times the Earth’s distance from the sun, beyond the orbit of Uranus.
A Journey of Millions of Years
Comet Bernardinelli-Bernstein has been traveling from the Oort Cloud for over a million years. Its entire orbit around the sun is an incredibly long one, estimated at three million years. The comet’s orbital path is significantly tilted relative to the plane of the solar system, with an inclination of about 95.4 degrees.
Its size easily surpasses that of the previous record-holder, Comet Hale-Bopp, by more than double. This massive comet is also incredibly dark, reflecting very little visible light, making it “darker than coal.” Unfortunately, it won’t get close enough to the sun to be visible to the naked eye from Earth.
The C/2014 UN271 Bernardinelli–Bernstein comet is a fascinating 120-150 km wide chunk of ice and dust, the largest comet we’ve detected in the Oort cloud.
It’s about 450 trillion tons, darker than coal, and has an extremely elongated orbit stretching from 10 AU to 55,000 AU! pic.twitter.com/Y4UtKUcaqf
— ToughSF (@ToughSf) March 23, 2024
The comet’s orbital path is highly inclined, and its trajectory could change slightly after it passes its closest point to the sun. While it is the largest known comet nucleus, it’s not the largest comet ever recorded. That title belongs to 95P/Chiron, a hybrid object classified as both an asteroid and a comet, with an average diameter exceeding 210 kilometers.
C/2014 UN271 (Bernardinelli-Bernstein) was first observed in 2014 but only now know just how big it is and headed this way.
With a nucleus 85 miles across & an estimated mass of 500 trillion tons but Earth is in no danger of a “Don’t Look Up” situation, astronomers say.#Comet ☄ pic.twitter.com/fPxyZzEbuU— ~ Inmaretta (@mariafedaviz) April 12, 2022
As Comet Bernardinelli-Bernstein continues its approach, it will become more observable and active. Astronomers anticipate further studies in the coming years, which may reveal a spectacular cosmic display, though a telescope with a lens diameter of at least 10-20 cm will be needed for clear viewing.
Key facts about Comet Bernardinelli-Bernstein
Comet C/2014 UN271 (Bernardinelli-Bernstein) is crucial for understanding the early solar system’s ice composition and the materials that formed planets. Scientists believe these objects formed in the early solar system and were later pushed to its outer edges by the gravity of giant planets like Jupiter and Saturn. There’s also interest in how such comets might have delivered water and organic compounds to Earth, potentially contributing to the origins of life.
“This comet literally makes the top of the iceberg, is a representative of many thousands of comets that are too weak to see them because they are mostly far from the Sun,” says astronomer David Jewitt of the University of California. “We have always believed that this comet must be really big, because it is very clear even at a relatively long distance. And then it was confirmed that it really was.”
The comet was first discovered in 2021, identified from data captured during the Dark Energy Survey between 2014 and 2018. Its closest approach to Earth will be around April 5, 2031, at a distance of 1.5 billion kilometers (0.93 billion miles).
- Comet Bernardinelli-Bernstein is the largest comet ever discovered, with a nucleus between 120-137 km wide.
- It is expected to reach its closest point to the sun on January 29, 2031.
- ALMA observations in March 2024 detected gas jets erupting from the comet’s icy core.
- The comet originates from the Oort Cloud and has an orbital period of about three million years.
- It is too dark and distant to be visible to the naked eye from Earth.
What is the Oort Cloud?
The Oort Cloud is a theoretical spherical shell of icy bodies located at the outermost reaches of our solar system, extending from about 2,000 to 200,000 astronomical units (AU) from the Sun. An AU is the average distance between the Earth and the Sun. Most objects in the Oort Cloud orbit around 50,000 AU away, nearly a light-year from the Sun. Occasionally, these objects are perturbed and sent towards the inner solar system, becoming comets.
