Jupiter is already the biggest planet by far in our solar system, but new research suggests it was somehow once even larger than it is now. Twice as large, in fact. To put that into context, those ...

Space. It's really, really big. How big is it? Well, according to astronomers, the observable universe is around 92 billion light-years in diameter, but that's all we can see (hence the word ...

Planetary size was determined pre-spacecraft by measuring the planet's angular diameter and its distance from Earth (in AU, later converted to terrestrial units after the AU was accurately measured ...