lately we have witnessed several "disappointments" in astronomy, starting from the failure of the red hypergiant star Betelgeuse, which promised an unprecedented show.
The comet recently made the disappointment worse C / 2019 Y4 ATLAS, which – according to some – should have become second to the Sun for brilliance, however this has not happened, and today we will explain why.
Where everything started
The cosmic stone was discovered by the ATLAS (Asteroid Terrestrial-impact Last Alert System) program on December 28, 2019. At the time of its discovery, the comet shone with magnitude 19.6 in the constellation Ursa Major. Further observations in the following days identified one foliage (a temporary atmosphere that is formed following the sublimation of volatile substances present on the surface) and also one cometary tail (a bright trail that follows the cosmic stone).
Small excursus: the magnitude of a celestial body is a measure of its brightness detectable by the Earth; the greater the brightness of the celestial object, the lower its magnitude. For example, the Sun has a magnitude of -26.74, Venus of -4.47 (not bad for a planet) and Betelgeuse -1.17.
What was considered a normal comet, between early February and late March it increased its brightness by 4000 times, going from a magnitude 17 to a magnitude 8. In short, the event attracted the curiosity of astronomers from all over the world, who began to point their eyes, or rather telescopes, towards the sky.
A new hope
The clamor of the news gave rise to many discussions on the particular celestial object, which even emitted a green color thanks to the diatomic carbon emissions. In March 2020, the comet's brightness increased by even four magnitudes.
In conclusion, the premises for the astronomical event of the decade (if not of the century) they were all right. Thanks to the rapid increase in brightness, in fact, the comet led to think that it could have become visible to the naked eye at the end of April 2020.
Broken hopes
However, this did not happen and as of March 17, experts noticed signs of a slowdown in brightness. The cosmic stone, in fact, around April 2, 2020 it seemed to have been shattered. Blame? Our Sun. Comets "inhabit" the exterior of our Solar System, an extremely cold place away from the warm rays of our star.
The approach to the Sun causes a considerable sublimation of their ice and a conspicuous emission of dust, accompanied in this case also by the fragmentation of the nucleus into several parts. In fact, recently the researchers of the Lulin One-meter Telescope in Taiwan have confirmed that the comet is breaking, with a fragment at 3,400km in front of the pair that follows it.
The images also suggest that before it reaches Mercury's orbit in late May, the comet will break completely. On the fate of ATLAS, experts are still uncertain: it could completely burn or produce an explosive sight as it approaches the Sun.
Is not all lost?
On April 11, however, amateur astronomer Michael Mattiazzo appears to have discovered a new comet while observing data from the Solar Wind Anisotropy (SWAN). The tool in question was not designed to find comets; its job is to detect hydrogen in the Solar System. However, since the comet is emitting a fairly significant amount of hydrogen in the form of water ice, it has been observed by SWAN.
The comet appears to be traveling up a very elongated elliptical orbit over a period of about 25 million years; this means that the last time it crossed the internal solar system may have been during the Oligocene era, the period when the largest terrestrial mammal ever existed walked on our planet: the Paraceratherium, a species of rhino about 5 meters high and 7 meters long.
Currently, the SWAN comet is visible only to those residing south of the equator. As of April 16, it had a magnitude of 7.8 and showed a head approximately one sixth of the apparent width of the Moon. This celestial object could "evolve" into an even brighter body, according to experts. Like ATLAS, the SWAN comet appears to be relatively small.
It will pass closer to Earth on May 12 at a distance of 83.3 million kilometers and will reach perihelion (the closest point to the Sun) on May 27, when it will be 64.4 million kilometers from our star.
Assuming that the cosmic stone continues to light up at the current rate, it could reach a magnitude of 3 during the last week of May, bright enough to be seen with the naked eye. Unfortunately, there are still several doubts and, even, it could follow the same fate as the comet ATLAS. I mean, let's keep our fingers crossed.
