No, it isn’t a Halo-type Ringworld seen from the side: it’s actually the Space Shuttle Atlantis’ Orbiter Boom Sensor System (OBSS) with a stunning backdrop of Earth and Aurora Australis. Here the OBSS is being grappled by the Canadarm, the Shuttle’s main mechanical arm which it uses to deploy and maneuver payloads like the Hubble Space Telescope. The OBSS was a fairly new addition to the now-retired Shuttle fleet and was tasked with checking the hull and heat shielding for damage before returning to Earth.
Aurora australis is another beast entirely. You’ve probably heard of aurora borealis, the “Northern Lights” that can be seen from within the Arctic Circle during the summer and winter equinoxes — and aurora australis is basically identical, but only visible from the southern hemisphere. There isn’t much land in the higher southern latitudes, and the only places you can really see aurora australis are from the southern most parts of Australia, New Zealand, South America, the Antarctic… and space!
The photo itself is taken from the International Space Station, and you can see some of its solar panels in the top left corner.