It’s difficult to know for sure how many electrons are in the Universe. British physicist Arthur Eddington (1882–1944) came up with a number in 1938, now known as the ‘Eddington number’. Eddington’s c

Might our universe – as vast as it is – be simply one of many? We look at the growing evidence that there’s more than one cosmos out there

GLOBAL EYE

Imagine you’re in a woodland, with sunlight filtering through the endless green canopy overhead. There’s uniqueness everywhere. Some trees grow bolt upright, but others are wizened and twisted. Here t

While our planet only has one easily visible Moon, several other tiny objects arguably deserve the title too

When comet 3I/ATLAS was discovered in July, on a one-way interstellar journey through our Solar System, Harvard astronomer Avi Loeb suggested it might be an alien spacecraft paying us a visit. Back in