Comet C/2014 UN271 Bernardinelli-Bernstein, currently heading between the orbits of Uranus and Saturn toward the center of the Solar System, was still considered an asteroid at the time of its discovery. The giant comet is estimated to approach the Sun in 2031, according to orbital calculations.
It was initially believed that a celestial body that appeared in the depths of the solar system was an asteroid
The celestial body, which was discovered in 2014, was initially identified as an asteroid due to its initial estimates being between 100 and 350 kilometers in diameter. Later, when he approached the interior of the solar system, it was discovered
That the orb suffers from a coma, that is, not an asteroid but a comet of enormous size.
In the outer solar system, comets freeze due to extremely cold temperatures of – 200 ° C, which is why it is difficult to identify them.
However, as they move toward the interior of the solar system, the water, gases, and other volatile matter frozen on the comet’s core begin to evaporate and seep out of the nucleus. Gaseous material flowing in this way forms an extensive quasi-atmosphere around the comet’s solid core, which astronomers call a coma.
As the comet approaches the Sun, the dust and gases emitted from the nucleus develop into a huge and extremely long plume under the pressure of the jet and the solar wind.
The diameter of the comet seeds known to date does not exceed 50 kilometers.
That’s why astronomers were shocked by the incredible large autoscale of C/2014 UN271, which their explorers have dubbed Comet Bernardinelli-Bernstein.
The first measurements proved that the huge bull is moving from the so-called Oort cloud at the edge of the solar system into the interior of the solar system.
Its diameter is ten times that of the dinosaur-killing asteroid KT.
Led by Pedro Bernardinelli and Gary Bernstein, who discovered the colossal rhythm, several large ground-based telescopes and the Terrestrial Exoplanet Reconnaissance Telescope (TESS) began examining the celestial body more closely.
Based on a detailed analysis of images taken from the body, the diameter of the UN271 core from C / 2014 was determined with relative accuracy, obtaining 150 km. By comparison, at the end of the Cretaceous period, approximately 65.5 million years ago, the diameter of the asteroid or comet nucleus that collapsed and caused a mass extinction in what is now the Gulf of Mexico was less than a tenth of that.
The researchers set the reflectance of the comet’s core, the so-called albedo, to 0.04, or 4%. It became necessary to confirm the value of its albedo and its diameter with other measurements.
This final decision was made by Emmanuel Lelouch, an astronomer at the Paris Observatory.
and her colleagues 54 radio transmitters of 12 meters and 12 meters in length using a 12-meter antenna system.
An important series of observations was made in August of last year, when C/2014 UN271 was still 20 astronomical units (CSE) from the Sun. (CSE is equal to the average distance of the Earth and the Sun is about 149.9 million km.) The French research team was able to determine the diameter of the comet’s nucleus from ALMA observations with a high degree of accuracy, with a value of 137. 17 km was obtained.
Comet Bernardinelli-Bernstein is twice the diameter of the Hell-Bopp nucleus of bright comet C/1995 O1, which could be seen from Hungary in the spring of 1997.
Current orbital computation data show that the proximity to Comet Bernardinelli-Bernstein will not greatly exceed that of Comet Saturn.
Imre Tóth: ALMA stands for: a truly massive comet approaching Saturn’s orbit, Astronomy News Portal, February 19, 2022
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