Scientists have invented a cloak inspired by Roman mythology that can cool anything it covers during the day and warm it up at night. The Janus thermal cloak, named after the two-faced Roman god Janus, could be used in everything from electric cars to space craft, with the researchers claiming it could even be used to build off-planet colonies on the Moon and Mars. “The thermal cloak is like clothes for vehicles, buildings, spacecrafts, or even extraterrestrial habitats to keep cool in summer and warm in winter,” said Kehang Cui, a materials scientist at Shanghai Jiao Tong University, who was involved in the research. “The cloak works basically the same way the Earth cools down, through relative cooling. The Earth is covered by the atmosphere, and the atmosphere is transparent to a certain range of electromagnetic energy we radiate.” The futuristic material, made of silica and aluminium, is able to achieve the heating and cooling effect passively, without the need for any outside energy. Covering electric vehicles in the cloak helps to cool them 8°C on a hot day and warm them 6.8°C on a cold night, helping to prevent deterioration of the battery. “This is the first time that we could achieve warming above the ambient temperature by almost 7°C during winter nights,” said Professor Cui. “This is also kind of surprising to us – there’s no energy input or sunshine and we can still get warming.” A study detailing the research, titled ‘Scalable and durable Janus thermal cloak for all-season passive thermal regulation’, was published in the scientific journal Device on Tuesday. Read More Record-breaking sugar battery could supercharge transition to renewable energy