Ch 01-01 A Tour to the Universe
Length scales in the Universe
[~ 10 m, the usual scale of the surroundings of a human being]
[~ 1 km, a certain fraction of a city]
[~ 100 km, about the distance between Hsinchu and Taichung]
[~ 10,000 km, about the size of the Earth]
[~ 1,000,000 km, the scale of the Earth-Moon system]
[~ 100,000,000 km, or 108 km, about the distance between the Earth and the Sun]
[~ 1010 km, or 10 billion km, about the size of the solar planetary system]
[~ 1012 km, or 1000 billion km (1 trillion km),
not yet reaching the neighborhood stars of the Sun]
[~ 100 trillion km, the scale of typical stellar separation around the Sun]
[~ 10,000 trillion km, or 1019 m, 1021 cm, an area of
a large number of stars]
[~ 1021 m, typical size of a galaxy]
[~ 10 23 m, about the size of a galaxy cluster;
beyond the cluster scale are the super clusters of galaxies (~ 1025 m),
which further form
the 'large scale structure' of the observed universe.]