BY THE NUMBERS

–98

The night-time temperature in degrees Celsius of the coldest places on Earth: tiny valleys in East Antarctica. Glaciologist Ted Scambos found the spots with satellite imaging, according to a study in Geophysical Research Letters.

100

The price in US dollars for a set of Biobits, a kit of synthetic biology experiments for schools. As described in two papers in Science Advances, the kits use freeze- dried starting material to produce colours, fragrances and hydrogels without complex equipment.

9.3

The percentage drop in corn production due to the loss of sunlight caused by the eruption of Mt Pinatubo in 1991. Dumping sulfates into the upper atmosphere to combat global warming could have a similar effect, according to a paper in Nature by Jonathan Proctor.

30

The number of quadcopters in the largest self- organising aerial drone swarm yet created. As described in a paper in Science Robotics by Gábor Vásárhelyi, the autonomous drones flock without colliding.