CRISPR catches

The beauty of butterfly wings owes much to just two genes, researchers revealed this month. They used the CRISPR gene-editing system to turn off the genes, called WntA and optix, to show how their absence dulls the colours of these fleeting flyers. Left are the wings of an unmodified Sara longwing (Heliconius sara sara) from the study; right is a gene-edited version.

Inside Xenon

Coming down…

At the start of the month, this Soyuz capsule brought back three astronauts to Earth, landing near Zhezkazgan in Kazakhstan. Among them was Peggy Whitson, who spent 288 days in space aboard the International Space Station.

… and going up

Ten days after Whitson and her colleagues returned to this planet, another three people left it when this Soyuz left for the space station from Baikonur Cosmodrome.

A complex cloud

This nebula — called the Rho Ophiuchi cloud complex — is 140 parsecs (460 light years) from Earth. Photographer Artem Mironov took three nights to capture this image of it, which went on to win this year’s Insight Astronomy Photographer of the Year award.

Seamount squid

On 17 September, the crew of the US National Oceanic and Atmospheric Administration’s ship Okeanos Explorer were exploring the Musicians Seamounts, a formation of undersea mountains in the Pacific Ocean, with remotely operated submersibles when they spotted this cranchiid squid. You can see more pictures of weird and wonderful deep-sea denizens on their diary site.

Bee bounty

Cassini comedown

It is finally over. The Cassini mission this month dived into Saturn’s atmosphere, destroying itself. In this photo, Cassini programme manager Earl Maize packs up his workspace at mission control in the Jet Propulsion Laboratory in Pasadena, California. on 15 September.

They grow up so fast

Enrico Sacchetti/Royal Photographic Society