Last year, scientists announced the discovery of? a giant comet Remnants within the orbit of Neptune. They calculated, based on its brightness, that its icy core would be between 99 and 200 kilometers long. If the estimates were accurate, it would be the largest comet ever discovered.
But scientists wanted to make sure the title was appropriate, so in January they reported Hubble Space Telescope for the comet and accurately measured its nucleus. As reported in this week The Astrophysical Journal letter, the comet nucleus can be up to 136 km in diameter, which is more than twice the width of the US state of Rhode Island (northeast of the US). It also has a mass of 500 trillion tons, which is roughly equivalent to 2,800 Mount Everest.
“It’s a hundred times bigger than the typical comets we’ve studied all these years,” said David Jew, an astronomer and planetary scientist at the University of California at Los Angeles and one of the study’s authors.
in spite of them impressive dimensions, the comet – named C/2014 UN271 (Bernardinelli-Bernstein), after two of its discoverers – will only be visible to the naked eye for a brief period. It is running towards the Sun at a speed of 35,200 km/h. But at its closest approach, in 2031, it will come within just 1.6 billion kilometers of the Sun — just behind Saturn’s orbit — where it will appear as a faint glow in the night sky before returning to shadow.
With Hubble’s help, however, astronomers can see and study this gleaming extraterrestrial visitor in all its glory, almost as if they were flying with it—a spectral blue haze covering an apparently dazzling white heart. He said, ‘The image she has is beautiful. Pedro Bernardinelli, one of the discoverers of the cometan astrophysicist at the University of Washington who was not involved in the study.
Despite its weight, the size of this comet’s nucleus proved difficult to measure. Although far from the Sun, a trickle of sunlight is enough to vaporize the core’s volatile carbon monoxide ions, creating a blinding dusty atmosphere called a coma.
Hubble Could not clearly see the nucleus of the comet through this haze. But by taking these high-resolution images of the comet with a space telescope, Jew and his colleagues were able to create a computer model of the coma, allowing them to digitally remove it from the images. With only cores remaining, it was easy to scale.
Their analysis also showed that its icy core is blacker than coal. This may partly result from being “baked by cosmic rays,” Jew said. High-energy cosmic rays are bombarding the core, breaking the chemical bonds on its surface. This allowed some of the lighter elements, such as hydrogen, to escape into space, leaving behind the darker carbon – making the core look like a highly toasted slice of bread.
This dark core suggests that the comet – despite its enormous size – is not much different from the others. “Comet nuclei are almost always superdark,” said Teddy Caretta, a planetary scientist at Lowell Observatory in Flagstaff, Arizona, who was not involved in the study. He suggests comparing the comet to a pile of snow on the side of the road. “Even though it’s still mostly snow, adding just a little bit of dirt and grime can make a pile of snow dirty and dark.”
As it approaches Saturn’s orbit, more mysteries of the comet will be revealed. But in 2031, when it begins to retrace its 3-million-year circuit from the Sun, astronomers won’t know much about its origins, most likely from the Oort cloud—the stuffy solar system. Around an imaginary and currently unattainable bubble primitive snowflakes of various shapes and sizes.
The comet is a welcome preview of what’s hiding inside this bubble. But “finding this thing is a reminder of how little we know about the outer solar system,” Jew said. “There are many things we haven’t seen and many things we can’t even imagine.”
He continued: “Who knows what’s going on there?”
Translated by Luiz Roberto M. Gonsalves
