Snworld

Why aren’t our Solar System’s planets and moons made from the same material? the solar system formed from the collapse of a molecular cloud consisting mostly of hydrogen, but also containing heavier elements. As the cloud collapsed, its central region began to heat up until eventually the hot ‘proto-sun’ was formed. the planets formed by the accretion of material from within this cloud. due to their high boiling points, only metals and silicates could exist in solid form in the hot, inner regions of the early solar system. More volatile elements either remained gaseous or were blown away by the sun’s energy. since this heavy material existed mainly in the inner regions of the solar system, the planets that formed there are small and rocky. in the cold outer reaches of the solar system, compounds with low melting points could remain in solid form. these ices were also much more abundant than the heavier elements. the outer planets were therefore able to grow much larger, and he...

Could direct air capture prevent climate change ? direct air capture (dAC) is an appealing way to tackle climate change: just pass ambient air over chemicals that absorb the Co2 driving global warming, and then use or store the Co2. dAC differs from the better-known carbon capture and storage (CCs) in that it can be done anywhere, not just at big sources of Co2 such as power stations. it’s more effective than natural Co2 ‘scrubbing’ using trees and plants, and can be performed where the Co2 is most easily stored or re-used. unlike CCs at power stations, dAC must be effective at removing the far more dilute Co2 in ambient air. this demands special equipment and chemicals, plus renewable energy sources producing zero Co2. that has led to grave doubts about the economic viability of dAC. For now, it remains an intriguing but impractical remedy for global warming. 

How do we know when something is wet?  our skin contains lots of nerve endings that respond to different stimuli. there are receptors for touch, vibration, heat, cold and pain – but not for wetness. water is such a ubiquitous component of all living cells that it would be difficult for a nerve cell to avoid firing constantly in response to its own composition. instead, wetness seems to be a property that our nervous system learns to recognise, based on a mixture of cold, pressure and texture. A 2014 study at Loughborough university found that hairy skin is more sensitive to wetness than smooth skin, which may be because hairy skin has more temperature sensitive nerve endings. when you are born, you don’t feel wet or dry, you just feel cold or warm. over time we learn that the feeling of cold cloth sticking to our skin means that we’ve sat on a wet park bench.

Why do snakes have slits for pupils? Vertical pupils are an adaptation for ambush hunting. A 2010 study at sydney university found that of 127 Australian snake species, the ones that ambushed their prey by night had vertical pupils, while those that actively chased down prey in the day had round pupils. the constriction of round pupils helps distant prey stay in focus, but it also lets in less light. Vertical pupils improve vision across a wider range of light levels, and enable the animal to detect horizontal movement more effectively. it’s also possible that vertical pupils are more camouflaged, since they break up the round outline of the eye

Farmers under pressure to reduce chemical pesticides can take heart from the news that the US Department of Agriculture is about to start trialling a device that can kill insects with a laser. Developed by Seattle company Intellectual Ventures Lab (IVL), the ‘Photonic Fence’ isn’t really a fence at all, but a small box containing lasers, cameras and an AI computer system. The cameras scan the air around the device for 100 metres, and the AI system measures the shape, speed, acceleration and wingbeat frequency of any bugs detected, to establish which are potentially harmful. Any insects identified as a threat can be zapped by the lasers, with a ‘kill rate’ of up to 20 insects per second. By deploying several such devices, farmers could effectively create a virtual fence around their crops that kills harmful pests but leaves bees and other beneficial or harmless insects unharmed. As well as protecting crops, it’s hoped the Photonic Fence could also prove useful in the fight agai...

The relationship between trees and air pollution is a complicated one. Particulate matter suspended in polluted air tends to settle onto leaves, and certain gases including nitrous dioxide (NO2) are absorbed by leaves’ stomata, filtering the air and reducing pollution levels slightly. But trees and other vegetation also restrict airflow in their immediate vicinity, preventing pollution from being diluted by currents of cleaner air. In particular, tall trees with thick canopies planted alongside busy roads can act like a roof, trapping pockets of polluted air at ground level. To reliably improve air quality, city planners need to give careful consideration to how trees are placed.