The universe is very large may be obvious, but sometimes it is worth remembering: the universe is very big ... if you think about it and ponder for a moment, the truth is not so obvious. Moreover, even really difficult to imagine how big it is.
Our usual measures are wasted when we put them face to face with the immensity that surrounds us. And one of the issues that most often appear when trying to measure the Universe is the same: How? How do astronomers know a star or galaxy is 8,000 million light years away?
The tools are different depending on the distance that separates us from the object to be measured ... from the parallax to help represent these cosmic beacons called Cepheids , astronomers make use of different methods to determine how many light years is the object in question .
The Royal Greenwich Observatory has released this video "Measuring the Universe" in which he explains in a very simple, and it invites you to the exhibition on the theme that remains open until September.