3I/ATLAS In just a few months, it has become one of the most talked about and monitored stellar bodies as it passes through our planet. Solar system. This comet was first detected on July 1 by the Warning System Telescope ATLAS -English acronym for Asteroid Earth Impact Last Alert Systemhence the name with which he was baptized. It is the third interstellar comet which is recorded, after 1I/’Oumuamua in 2017 and 2I/Borisov in 2019, which is why it has generated logical interest. At the end of last month the comet from beyond our Solar System reached perihelion, its closest approach to the Sun, and on December 19 it will reach the closest point to Earth, which will still be quite far away, at a minimum distance of 270 million kmaround 1.8 times the Earth-Sun distance.
Then more will be known about its peculiarities, which it has already exhibited a few and which have led to speculation about a possible alien nature and hostile intentions. This extravagant theory has been fueled by media based on the statements of the astronomer Avi Loebwho has the prestige of having been director of the Astronomy department at Harvard University for almost a decade, but who tends to see extraterrestrial spacecraft with some ease. He speculated on this possibility with 1I/’Oumuamua and has now been doing it for a few months with 3I/ATLAS.
Regarding the third interstellar body detected, he even said that ‘the solar eclipse of 3I/ATLAS seen from Earth during perihelion would allow it to carry out a clandestine reverse Oberth solar maneuver, an optimal braking strategy for interstellar ships that want to be linked to the Sun. A possible optimal encounter with the Earth would occur at the end of November or beginning of December 2025.’ It is also fair to point out that, in his first writing on the subject, Loeb warned that this possibility is ‘fun to explore, regardless of its validity‘.
In any case, the POT and the THAT At no time have they had any doubts about the nature of 3I/ATLAS, which they have always considered a comet, and now a new observation made by an observatory in South Africa has confirmed a typical behavior of this type of stellar bodies.
It has been since South African Radio Astronomy Observatoryusing the radio telescopeMeerKATmade up of 64 satellite dishes of 13.5 meters in diameter each, which have been detected for the first time in 3I/ATLAS a common radio signal in comets.
As explained by the authors of the observation in The Astronomer’s Telegram, it is ‘OH absorption on the 1665 MHz and 1667 MHz lines’. This is a radio frequency pattern with radio absorption lines through hydroxyl radicalsthat is to say, OH.
MeerKAT detected how the gas surrounding 3I/ATLAS slightly reduces the intensity of the radio signal at those two frequencies that are the typical fingerprint of the hydroxyl radical, a fragment of the water molecule. Virtually all known comets contain water ice.
That pattern is just what you’d expect from an active comet. As it approaches the Sun, water ice evaporates – a process known as sublimation-the Sun’s radiation breaks the molecules and these new OH molecules appear. Given the apparent closeness between the comet and the Sun in Earth’s sky, That gas acts as a filter and we see the lines in absorptionnot in broadcast. OH is detected in many other places in the cosmos and helps locate water and regions where stars are born.
The telescope had already observed 3I/ATLAS to try to detect radio signals before, on September 20 and 28, but it was not until October 24, when the comet was about to reach its perihelion, that it was possible.