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?
