This is potentially excellent news for ESA's Comet Interceptor mission, due to launch later this decade.

It adds further weight to the idea that these interstellar interlopers may be quite common, raising the chances that Comet Interceptor will be able to target a flyby past one from its Sun-Earth L2 loiter orbit.

And with the Rubin Observatory now online, surveying the whole southern sky every three nights, many more such objects may soon be discovered.

3I/ATLAS is thought be around 20km in size, so considerably larger than either of the previous interstellar objects.

It's currently out near the orbit of Jupiter, but there have been reports of some faint comet-like activity – that should become more apparent in the weeks months to come.

The observations support the idea that SNR 0509-67.5 was generated by a white dwarf, which formed a blanket of helium stolen from a companion star. This helium became unstable and ignited, sending a shockwave around the white dwarf and inwards. The explosion triggered a second detonation in the core of the star, ultimately creating the supernova.

The fingerprint left by this process? Two separate shells of calcium found in the supernova’s remains.

Read more: https://www.eso.org/public/news/eso2511/