Pic of the Week: The Third Interstellar Visitor

This week’s image is from the NASA/European Space Agency’s (ESA) Hubble Space Telescope. It shows an image of interstellar comet 3I/Atlas from July 21, 2025. The comet was about 365 million kilometers from Earth. First identified by a telescope in Chile last month, this is the third such object to be observed by astronomers.

Here is a little more from the ESA about this unusual object:

Hubble also captured a dust plume ejected from the Sun-warmed side of the comet, and the hint of a dust tail streaming away from the nucleus. Hubble’s data yields a dust-loss rate consistent with comets that are first detected around 480 million kilometres from the Sun. This behaviour is much like the signature of previously seen Sun-bound comets originating within our Solar System. The big difference is that this interstellar visitor originated in some other Solar System elsewhere in our Milky Way galaxy. 3I/ATLAS is traveling through our Solar System at roughly 210,000 kilometres per hour, the highest velocity ever recorded for a Solar System visitor. This breathtaking sprint is evidence that the comet has been drifting through interstellar space for many billions of years. The gravitational slingshot effect from innumerable stars and nebulae the comet passed added momentum, ratcheting up its speed. The longer 3I/ATLAS was out in space, the higher its speed grew.