A gigantic galaxy is orbiting our very own Milky Way, and we only find out about it now, says a new research published in Monthly Noticed of the Royal Astronomical Society.
Either it has magically appeared recently (back in January), or we have been blind to its existence. The discovery has been described as a “very rare” one by lead author Vasily Belokurov from the University of Cambridge. The dwarf galaxy, named Crater 2, has, in reality, been there all the while. It remained inconspicuous for all this time because its stars are so scattered that it is specially dark, and it thus remains hidden; Belokurov says it is somewhat of an invisible object.
400,000-light-years-away, Crater 2 earns the fourth position among the largest known galaxies orbiting ours. Otherwise, a total of 49 galaxies are known to be circling the Milky Way galaxy. Given that the new surprising discovery has revealed the presence of a particularly dark one, we might be having others that are as dark or darker orbiting the Milky Way, and we wouldn’t even know it.
Crater 2 was spotted thanks to a computer algorithm that is used to detect regions marked by unusual aggregations of stars. Crater 2 is actually one such cluster.
According to the astronomers, Crater 2 makes around 7,000 light years in half-light diameter; the latter term is used to denote the diameter of a galaxy with respect to the part emitting half its light. Were we to perceive it, it would appear twice the size of the full moon. The picture below is an illustration of how it would like had it been 1,000 times brighter, with the moon in the foreground for us to have some idea of the size.
This discovery further solidifies the concept that the more we come up with answers, the more questions arise: an answer leads to more questions. Imagine how many galaxies are actually out there beyond our eyes and knowledge.