This video explains how we can measure the distance to near and far objects in the universe using parallax, 'standard candles' and the Doppler effect.
Astronomy & time
Measuring the Universe
Time fact files
Doctor Who Confidential
Karen Gillan (aka Doctor Who's Amy Pond) visits the Royal Observatory Greenwich.
Clip from Doctor Who Confidential, Series 5 Ep. 11: Extra Time. First broadcast BBC Three, 7:30pm 12 June 2010. Used by permission.