What is the sky like on other planets?

question João Pedro MS, Rio de Janeiro, RJ illustrates Samuel Leme edition Felipe van Deursen It varies a lot, of course. Basically, there are four factors involved: composition of the atmosphere, illumination from nearby stars, particles suspended in the air,…

What is the Pinocchio paradox?

ILLUSTRATES Elias Fernandes QUESTION Franklin Chagas Damasceno, Cariacica, ES Paradoxes are apparently true statements that nevertheless contain a logical contradiction. The so-called Pinocchio paradox, specifically, is a variant of a more general one, that of the liar, which has driven…

How do fireflies emit light?

It’s all just a nice chemical trick. The oxygen that is inhaled by the firefly reacts with substances in its body and the result is the release of energy in the form of light. Scientists call this phenomenon bioluminescence and…

How does caries develop?

It is caused by bacteria that produce acids capable of corroding the tooth, forming a small hole. The development of decay takes from a few weeks to several months, but the pain only appears when the «digging» approaches the pulp…