Observations of what scientists believe to be the first interstellar comet ever identified. Image credit: IAC/Miquel Serra-Ricart
Astronomers are rushing to study what appears to be the first known interstellar comet — and in some of the very earliest observations, it looks oddly familiar.
The object, currently dubbed Comet C/2019 Q4, was first spotted on 30 August 2019. Follow-up observations of its path suggest that the comet is skimming through our neighbourhood on a one-way journey, not trapped in the looping orbit typical of objects born in our own Solar System. That would make it only the second confirmed interstellar object, after ‘Oumuamua, which was spotted in 2017.
But scientists couldn’t get a good read on what ‘Oumuamua was made of. With this object, however, they can get such readings, by measuring the light signature of the gunk surrounding the comet. Some of the first of those spectra for C/2019 Q4 are in, and they look pretty similar to the spectra of a class of objects in our Solar System. This suggests that those objects and the interstellar visitor consist of more or less the same stuff.
“Comets in other planetary systems can be similar to those of the solar ...