When humans look up at the night sky, they naturally ask the question: How far away is that planet, or that star, or that galaxy? Distance is one of the most fundamental measurements astronomers make, ...

How far away are the most distant objects in the Universe? How has the Universe expanded over the course of its history? And therefore, how big and how old is the Universe since the Big Bang? Through ...

The cosmic distance ladder is the world’s longest ruler, built to measure the universe. Since the time of the ancient Greeks, scientists have been constructing a cosmic measuring tape to measure the ...