"We've never seen anything exactly like the Cow, which is very exciting. We think a tidal disruption created the quick, really unusual burst of light at the beginning of the event and best explains Swift's multiwavelength observations as it faded over the next few months."
Source: Amy Lien, an assistant research scientist at the University of Maryland, Baltimore County and NASA's Goddard Space Flight Center in Greenbelt, Maryland, commenting on a brief and unusual flash spotted in the night sky on June 16, 2018, which puzzled astronomers and astrophysicists across the globe. The event — called AT2018cow and nicknamed "the Cow" after the coincidental final letters in its official name — is unlike any celestial outburst ever seen