Lava lake. Red hot molten rock oozes and bubbles in the crater of one of the world’s most active volcanos, Mount Nyiragongo in the Democratic Republic of the Congo. Nyiragongo is more than 3,000 metres tall, and has erupted around 30 times since the 1880s. The last major eruption was in 2002, but for now volcanic activity is confined to the crater. The hike to watch the lake of sizzling lava at the summit is popular with tourists.

Martian valley. A crater on the surface of the red planet measuring 1 kilometre across was snapped by HiRISE, the camera on board NASA’s Mars Reconnaissance Orbiter spacecraft, as it zoomed in on the red planet’s Zarqa Valles in the Libya Montes highlands. Researchers hope that studying features like this in detail will provide clues as to how material is eroded and deposited on Mars.

New York, New York. Swedish climate activist Greta Thurnberg arrived in New York City on 28 August after a 15-day voyage across the Atlantic on board the zero-carbon yacht the Malizia II, which was fitted with sensors to measure the ocean’s temperature, pH and carbon dioxide levels during the crossing. The 16-year-old will attend the upcoming United Nations Climate Change Summit in New York before travelling to Chile for the COP25 climate conference in December.

Beetle close-up. This false colour scanning electron microscope image of a confused flour beetle ( Tribolium confusum ), taken by David Spears, was shortlisted in the Royal Photographic Society’s science photographer of the year competition. The species is a common insect pest known for infesting flour and grain.

Icy farewell. Icelandic scientists held a memorial service on 18 August for Okjökull, a glacier that once sat on top of the Ok mountain and has now almost disappeared. At the beginning of the twentieth century the glacier, in the country’s west, is thought to have covered nearly 40 square kilometres, but it has now lost its status as a glacier and was declared dead in 2014. These satellite images show the ice cover in 1986 (left), by which time the glacier had shrunk to a fraction of its former size, and in 2019 (right). A memorial plaque was unveiled at the site, warning that other glaciers are likely to meet the same fate in future years.

Glow-in-the-dark shark. This species of catshark ( Scyliorhinus retifer ) is biofluorescent — its skin absorbs blue light from the ocean and then emits light with a longer wavelength, creating patterns that can only be seen by other sharks. Researchers discovered that this is down to a previously undescribed family of small molecule metabolites present in the tiny tooth-like scales that make up the sharks’ skin. The scientists think these fluorescent molecules might also be involved in immune response, because initial experiments show that they have antimicrobial properties.

Telescope test. Engineers assembling NASA’s James Webb Space Telescope have connected the two halves of the telescope together after carrying out a successful test deployment of the support structure that will hold its secondary mirror in place. The completed telescope is scheduled to launch in 2021, taking over from the Hubble Space Telescope as the agency’s main astronomical observatory.

Slash and burn. These satellite images show rapid deforestation of a 48 kilometre-wide area in the Brazilian state of Rondônia over the past four years, as patches of rainforest are cleared by burning and converted to roads or agricultural plots. Rondônia has become one of the places in the Amazon affected most by deforestation — once home to more than 200,000 square kilometres of rainforest, an estimated 67,000 square kilometres had been cleared by 2003.

Stellar shock wave. The giant star Zeta Ophiuchi is 20 times more massive and about 80,000 times as bright as our Sun. As it hurtles through space at 24 kilometres per second it creates a bow shock — a set of glowing ripples produced when hot stellar winds collide with the surrounding dust. The image was taken by NASA’s Spitzer Space Telescope using its infrared camera, and is one of 16 images highlighted to celebrate Spitzer’s 16 ^th birthday.

Space hopper. Following a successful test flight of its prototype rocket Starhopper, SpaceX is now one step closer to its goal of beginning commercial space flights in 2021. Starhopper launched on 27 August in Boca Chica, Texas, rising around 150 metres into the air and hovering sideways before landing just under a minute later. SpaceX will use the tests to update the design of its Starship spacecraft, which is being developed to carry passengers in space.