One of the biggest comets goes our way

Nearly four and a half billion kilometers from the Sun – 29 times more than the Earth’s orbit – a small link of sunlight hit an object fast towards our cosmic environment. An icy substance. And something unimaginably old and vast.

About four hours later, at dawn on October 20, 2014, a telescope in the Atacama Desert of Chile took a giant photograph of the southern sky, focusing its sharp view on the night sky and showing the first glimpse of reflected light.

But it will take seven more years for researchers to identify the strange bright spot from the early days of the solar system – the largest comet ever seen with modern telescopes. This material is called Bernardinelli-Bernstein and its existence was announced last June. Astronomers now have all the information they can gather about the celestial body In the first scientific explanation Letters from the Journal of Astronomy Published.

“My phone kept ringing – I didn’t expect the scientific community to be so interested in the discovery,” said Pedro Bernardinelli, a doctoral researcher at the University of Washington. He discovered the comet during the final weeks of his PhD research at the University of Pennsylvania, along with his then mentor Gary Bernstein. “Overall, this is pretty much it.”

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According to recent estimates, the comet’s nucleus – the true celestial body – is about 150 kilometers in diameter. This is the largest estimate for a comet in decades. In comparison, the comet 67P / Churyumov-Gerasimenko, studied between 2014 and 2016 ESA Space Exploration Rosetta, Not more than four kilometers in diameter.

Michael Bunnister, an astronomer at the University of Canterbury in New Zealand, who was not involved in the first issue of the comet, said, “We are moving from city-wide comets to island-wide comets. In 1729 he traveled through the inner solar system.

As Bernardinelli-Bernstein approaches the Sun, the comet brightens and the inner planets penetrate from below the disk base that orbits the Sun. Its closest approach to Earth is January 21, 2031, which is more than a billion miles from the Sun – slightly farther away than Saturn’s average orbit. After that, Bernardinelli-Bernstein will begin a long journey to the floodplains of the solar system, well known in the 1940s and lasting for decades.

Depending on the amount of gas the comet emits, its icy surface evaporates with the sun’s radiation, and Bernardinelli-Bernstein can shine in the night sky like Saturn’s largest moon, Titan. In that case, the comet will be visible in 2031 with a reasonable amateur telescope.

But Bernardinelli-Bernstein is also special because he is the greatest distance he has ever seen. The ice object comes from the Oort cloud, the largest spherical nebula of small celestial bodies orbiting the Sun thousands of times farther away than Earth and the Sun.

Astronomers estimate that it will take millions of years for the comet to complete one orbit around the sun. So far, only three such “long-lived comets” have been found on the way from the Ort cloud to the inner solar system, and Bernardinelli-Bernstein was found 4.4 billion kilometers from Earth. A comet. With the discovery of the celestial body so soon, a whole generation of astronomers will have the opportunity to understand the mysteries of this comet.

A drop of light

Vector M., part of the Cerro Tololo Inter-American Laboratory in the Atacama Desert, Chile. Bernardinelli-Bernstein drew the attention of mankind to the extraordinarily sensitive digital camera fitted to the Blanco telescope.

The camera does not specifically search for celestial bodies from a distance in the solar system. It is the primary data collection tool of the Dark Energy Survey, a long-term project that captured more than 80,000 images of the southern night sky between 2013 and 2019. This dataset is vast in its search for possible explanations for dark energy, and it is believed that the mysterious force may have contributed to the rapid expansion of the universe. But images that want to read about dark energy and other cosmic phenomena can also be used to detect objects near home.

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For his PhD research, Bernardinelli used images from the Top Energy Survey to observe previously undiscovered objects in their orbit around the Sun beyond Neptune’s orbit. It is not an easy task. Each shot was so large that at maximum resolution it would cover the grid of 275 high quality TV screens. Bernardinelli searched for these tens of thousands of images for light spots a few pixels in diameter.

To facilitate his search, Bernardinelli wrote computer code that allowed the Dark Energy Survey to search for images of light moving in the immobile background of distant stars. After six months of complex calculations at a cluster of about two hundred computers at the Fermi National Accelerator Laboratory in Batavia, Illinois, Bernardinelli kept a database 817 newly discovered objects About whose orbits do not match the celestial bodies known in the solar system. As a final step, Bernardinelli and Bernstein personally checked these code calculations to make sure the computer code had done its job properly.

That’s what they noticed about the strange object: a celestial body with a brightness comparable to the worlds over an area of ​​about 150 kilometers. This object was beyond the orbit of Neptune, but it had a very irregular orbit that, as is common to long-term comets, came from an area thousands of billions of kilometers away from the Sun.

Bernstein says tracking comets is “a real needle-a-straw.” “But I was able to find something like a little icing on the cake!”