Floods, fires and fluorescent fish — September’s best science images

Fish out of water. Scientists captured a zebrafish embryo’s development over 12 hours using a specially designed microscope and a non-destructive technique called light-sheet imaging. The purple colour shows the position of the mesoderm, one of the groups of cells that eventually go on to form the embryo’s organs and tissues.

Credit: Loīc A. Royer and Merlin Lange/CZ Biohub

At-risk reptiles. Biologist Alejandro Arteaga handles Atractus snake specimens found during an expedition to remote Andean towns in Ecuador. Arteaga and his team found three previously undescribed species of snake living underground in obscure locations including a graveyard and an old church. Two of the species are thought to be facing a high risk of extinction in the near future.

Catching rays. This aerial view shows part of the Cerro Dominador solar- and photovoltaic-power plant in Chile’s Atacama Desert, one of the driest and sunniest places on Earth. The plant, which opened earlier this year, comprises a 250-metre-high tower surrounded by more than 10,000 mirrors — called heliostats — spread over 7.5 square kilometres. The heliostats reflect the Sun’s radiation onto a receiver at the top of the tower, where the heat is transferred to a system that drives an electricity-producing steam turbine. The project is part of Chile’s national renewable-energy programme, which aims to get 20% of the nation’s energy from renewable sources by 2025.

‘Tree-ring’ astronomy. This unusual image won the innovation category of the 2022 Astronomy Photographer of the Year Awards. It was created by artist Pauline Woolley, who compiled 26 images of the Sun from the first part of the solar cycle, taken by NASA’s Solar Dynamics Observatory. “The oldest ‘ring’ lies in the centre while the most recent sits furthest away,” says Woolley. Month by month, the rings grow like the rings of a tree. “The overall image is a marking of the passing of time, which incorporates visual evidence of increasing levels of solar activity apparent in the dark markings of solar flares,” she adds. The colours of the image have been adjusted to enhance its tree-like appearance.

Credit: Pauline Woolley, Solar Dynamic Observatory 

When nanoparticles meet. This atomic-scale video shows two disc-like nanoparticles merging together in real time. The particles consist of a core of cadmium atoms surrounded by a shell of cadmium chloride. Using a microscopy technique called liquid cell transmission electron microscopy, researchers were able to examine, for the first time, how these particles grow and interact. Their findings were surprising. When two particles merge into one big one, the direction of growth is guided not by the difference in their size — as theory dictates — but by a crack defect in the shell of the larger nanoparticle. “This is a huge milestone. We are rewriting textbook chemistry, and it’s very exciting,” said Haimei Zheng, a materials scientist at the University of California, Berkeley.

Record rainfall. Pakistan experienced its worst floods this century as rivers burst their banks, leaving huge swathes of the country under water. Flash floods destroyed roads, buildings and infrastructure, displaced millions of people and led to at least 1,200 deaths. Scientists say several factors contributed to the extreme event, including phenomenal heatwaves and a longer, stronger monsoon season with record amounts of rain.

Seeing double. The world’s oldest two-headed tortoise — named Janus, after the two-faced Roman god — celebrated his 25th birthday on 3 September. The Greek tortoise (Testudo graeca) was born at the Geneva Natural History Museum in Switzerland and has lived there ever since. He has two hearts, two sets of lungs and, according to museum staff members, two separate personalities. “The right head is more curious, more awake, it has a much stronger personality,” says handler Angelica Bourgoin. “The left head is more passive and loves to eat.”