Biggest comet ever discovered, Bernardinelli-Bernstein, is heading towards us

Seven years ago, a pair of scientists browsing high-resolution images of space spotted a glowing round object stealthily from a vast cloud of icy objects more than two billion kilometers from Earth.

As if this whole scene wasn’t exciting enough, the object appeared to be a huge comet. Thought to be between 60 and 100 miles wide, it was the the biggest comet that a human being has ever seen. And he seemed to be heading towards us, very vaguely speaking.

Last month, the discoverers of the giant object, University of Pennsylvania astronomers Gary Bernstein and Pedro Bernardinelli, combined their previous data with new sightings of the distant object this summer and confirmed their suspicions.

Yes, it is a megacomet. “The almost spherical cow of comets,” they joked in the title of their article, which they submitted for publication in Letters from the astrophysical journal September 23. And the pair also learned that the comet’s trajectory oscillated between Uranus and Saturn in 2031.

Besides setting up a great astronomical joke, Comet Bernardinelli-Bernstein is a very rare and unique prize for any scientist trying to piece together the history of the solar system. “In essence, it’s a time machine,” Amy Mainzer, an astronomer and comet expert at the University of Arizona, told The Daily Beast. The comet’s journey is the opportunity of a lifetime for scientists keen to learn about the conditions and building blocks of the solar system that once led to Earth and all of its life.

A comet is a returning visitor from the collisions of space rocks that created the Earth and almost everything in our corner of space a very long time ago. “The story the comet tells would tell us what existed in the solar system billions of years ago, and we can use it to understand things we see today elsewhere in the solar system,” he said. Bernardinelli told The Daily Beast.

But every comet we’ve had the chance to study closely so far has changed a lot over time, either because they were too small to avoid fragmentation or because they have passed so close to the Sun. that they were in the intense heat of the star, altering their chemistry. This means that the story he tells about the early solar system was, to say the least, edited by outside forces.

Bernardinelli-Bernstein escaped both destinies. “It’s a virgin,” Bernardinelli said. “Not much has happened to this object since its formation in the early days of the solar system, so we can think of it as a window into the past.”

Because it is so much bigger than other known comets – the famous comet Hale-Bopp, which itself is larger, is only 60 kilometers in diameter – Bernardinelli-Bernstein has enough gravity to hold itself together while she lazily lays around in space. It’s harder to separate.

The extreme distance of the comet from the Sun has also contributed to its preservation. “He spends most of his time in the deep freezing of the outer solar system,” Mainzer explained. Models of the megacomet’s orbit indicate that it last entered our part of the solar system about five million years ago and has not come close to Uranus. From this distance, the heat of the Sun barely touched him.

Mainzer says that as a result, the comet she affectionately calls “BB” likely resembles the original chemical state of the gas and dust nebula that formed our solar system about 4.5 billion years ago. ‘years.

Nasa

Its close-up approach in 2031 will be a monumental time to study comet chemistry and reveal what our part of the country looked like before planets circled around it. “One of the best things about this comet is that we have some time until it comes closest to the Sun, so we have years to study how it lights up when its surface is exposed. in the heat of the Sun. ” Mainzer said.

This warm-up act is essential, as it causes a comet to release huge amounts of dust particles and produce that distinctive comet tail. “By watching the show as the comet draws closer, we will be able to learn more about the chemicals that act as the propellant in the spray can, so to speak, pushing rock particles and dust off its surface,” Mainzer explained. .

What does not detaching itself from the surface of the megacomet is as important as this Is. Are the reactions carbon dioxide-based or nitrogen-based? Current observations suggest that Bernardinelli-Bernstein contains a lot of the former but relatively little of the latter, Bernstein said.

This mix counts. Nitrogen is very common on Pluto, the tiny planet (or “planetoid,” if you side with the critics) that is further from the Sun than any other major planet. It is possible that Pluto still has its nitrogen because it is too far from the Sun for this chemical to evaporate.

If Bernardinelli-Bernstein is really poor in nitrogen, “maybe that means this comet lived closer to the Sun than Pluto when it was young,” Bernstein said. This could make Bernardinelli-Bernstein a closer relative to our own planet than Pluto is, chemically speaking.

Mainzer pointed out that the older, cooler internal layers of the comet that don’t heat up easily could be even more interesting, as they could help reveal what exactly included the cloud of gas and dust from which our solar system. was born.

We can, in other words, fill in some of the vast gaps in the chemical planes of our own evolution and come closer to understanding where life and the planets that support it come from.

WATCH / LCO

Despite all its promises, there is also a downside to Bernardinelli-Bernstein’s recent discovery. A decade or more may seem like a long time to study a single object in space. But considering the time it takes to conceptualize, finance, organize, and execute a new space mission, it’s actually not very long at all. The only tools we can rely on to examine the megacomete are the ones we already have or are nearing completion.

“Big telescopes are our best bet now,” said Bernardinelli. These include the same telescopes that astronomers once used to inspect Bernardinelli-Bernstein as well as the optics of the Vera Rubin Observatory which is slated to open in 2023. Bernstein said it was possible the new space telescope NASA’s James Webb, which is slated to launch later this year, could also spend some time pointing to the mega-comet.

It is highly unlikely that NASA or another space agency will build a probe to intercept and collect Bernardinelli-Bernstein samples (which is ironically what NASA is currently doing with the asteroids surrounding Jupiter).

But that’s not impossible, and Mainzer, for his part, isn’t giving up hope that a space agency might see the value in recovering a real piece of Bernardinelli-Bernstein ice – and do what it wants. required to assemble a probe. “I think BB would be a great target for a close and personal visit,” she said.