Comets living in deep space are among the oldest objects in the solar system. These ice “Lego blocks” are remnants of the planet’s early days. They were unconsciously kicked out of the solar system in a game of gravitational pinball between giant outer planets.
The emitted comets settled in the Oort Cloud, a huge group of distant comets that surround the solar system for billions of miles in deep space.
What Is A Comet?
A comet has an amazing multi million-mile-long tail, which makes it look like a skyrocket, hiding the fact that at heart is a solid nucleus of ice mixed with dust like a dirty snowball.
Most comet nuclei measure a few miles across and could fit inside a small town, but Hubble astronomers have uncovered a whopper.
Comet C/2014 UN271 (Bernardinelli-Bernstein) could be as big as 85 miles across, which is twice the width of the state of Rhode Island.
Comets have been falling towards the sun for over a million years. It comes from a place that is believed to be home to trillions of comets called the Oort Cloud.
Diffuse clouds are believed to have inner edges between 2000 and 5000 times the distance between the Sun and Earth. Its outer edge can extend at least a quarter of the distance to Alpha Centauri, the star closest to our Sun
When Was Comet C/2014 UN271 Discovered?
Comet C/2014 UN271 was discovered by Pedro Bernardinelli and Gary Bernstein in archival images from the Dark Energy Survey at the Cerro Tololo Inter-American Observatory in Chile.
It was first observed in 2010. Hubble observations in 2022 were needed to discriminate the solid nucleus from the huge dusty shell enveloping it, with help from radio observations it was around 3 billion miles from the Sun, the average distance from the Sun to Neptune.
Since then, it has been intensively studied with the help of ground telescopes and space telescopes. The comet is now less than two billion miles from the Sun and will return to the Oort Cloud’s nest within a few million years.
Size Of The Largest Comet Discovered
NASA’s Hubble Space Telescope has measured the size of the largest icy comet nucleus ever seen by astronomers. The estimated diameter is about 80 miles in diameter.
The nucleus is about 50 times larger than the nucleus of most known comets. Its mass is estimated at 500 trillion tons, which is 100,000 times the mass of a typical comet much closer to the Sun.
The previous record holder was Comet C/2002 VQ94 with a nuclear diameter of about 60 miles. It was discovered in 2002 by the Lincoln Near-Earth Asteroid Research Project (LINEAR).
Location Of The Comet
The comet C/2014 UN271 (Bernardinelli Bernstein) is flying at the edge of the solar system at 22,000 miles per hour. But we don’t have to worry as it won’t get any closer than a billion miles to the Sun, which is just a little further than the distance from the Sun and Saturn also not before 2031.
“This comet is literally the tip of the iceberg among thousands of comets that are literally too faint to be seen in more distant parts of the solar system,” said David Jewitt, professor of planetary science and astronomy at the University of California, Los Angeles.
UCLA and co-author of a new study in The Astrophysical Journal Letters. “We always suspected that this comet was large because it was so bright at a great distance. We now confirm this to be the case.”
“This is a spectacular object considering how active it is while still far away from the sun,” said lead author Man To Hui of the Macau University of Science and Technology in Taipa, Macau.
“We speculated that the comet was quite large, but we needed the best possible data to confirm it.” Thus, his team used Hubble to take five pictures of the comet on January 8, 2022.
Observations About The Characteristics Of The Comet
The difficulty in measuring this comet was how to distinguish between a solid nucleus and the massive dusty coma surrounding it. The comet is currently too far away for Hubble to distinguish its nucleus with the naked eye.
Instead, Hubble data shows bright bursts of light at the location of the core. Hui and his team then created a computer model of the ambient coma and tuned it to match the Hubble image. Then the coma light was subtracted, leaving a star-shaped core.
Hui and his team compared the brightness of the core with early radio observations from the Atacama Large Millimeter/Submillimeter Array (ALMA) in Chile. This combined data limits the diameter and reflectivity of the core.
The new Hubble measurements are close to the initial size estimate of ALMA, but strongly suggest a darker core surface than previously thought. “It’s bigger and blacker than coal,” Jewitt said.
The Oort Cloud comet wasn’t really that far from the sun. Instead, while the orbits of Jupiter and Saturn were still developing, they were kicked out of the solar system billions of years ago by a gravitational “pinball game” between giant outer planets. Distant comets return to the sun and planets only if their distancet orbits are hampered by the gravity of a passing star, such as shaking an apple from a tree.
Comet Bernardinelli-Bernstein orbits about half a light-year from the Sun in an elliptical orbit about 3 million years long. Comets are now less than two billion miles from the Sun and fall almost perpendicular to the plane of our solar system.
At this distance, the temperature is only minus 348 degrees Fahrenheit. But it’s warm enough for the carbon monoxide to sublimate from the surface to form a dusty coma.
Comet Bernardinelli-Bernstein provides valuable clues to the size distribution of comets in the Oort cloud and thus their total mass. Estimates of the mass of the Oort cloud vary widely, reaching 20 times the mass of Earth.
What Is An Oort Cloud?
It was first proposed by Dutch astronomer Jan Oort in 1950, the Oort cloud remains a theory today. Because the myriad comets that make up it are too faint and far away for direct observation.
Ironically, this means that the largest structures in the solar system are barely visible. A pair of NASA’s Voyager spacecraft is estimated not to reach the inner region of the Oort Cloud for the next 300 years, and could take up to 30,000 years to pass.
The evidence comes from a falling comet that can be traced back to this nesting site. They approach the sun from all directions. This means that the cloud must be spherical. This comet is a frozen sample of the early solar system composition preserved for billions of years.
The reality of the Oort cloud is confirmed by theoretical modeling of the formation and evolution of the solar system. The more observational data we can collect through deep space exploration combined with multi-wavelength observations, the better astronomers will understand the role of the Oort cloud in the evolution of the solar system.
The Hubble Space Telescope is jointly operated by NASA and the European Space Agency (ESA). The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble’s science work. It is operated for NASA by the Association of Astronomy Research Universities in Washington DC.