Using parallax calculations, the Milky Way galaxy alone can be directly observed to have a diameter of approximately 80-100,000 light years. Calculations based on the observed brightness of supernovas of known energy output can determine the distance to more distant objects. The most distant object known is a star cluster approximately thirteen billion light-years away from Earth, observed by the Hubble telescope using gravitational lensing<ref>http://news.bbc.co.uk/1/hi/sci/tech/3490657.stm</ref>. | Using parallax calculations, the Milky Way galaxy alone can be directly observed to have a diameter of approximately 80-100,000 light years. Calculations based on the observed brightness of supernovas of known energy output can determine the distance to more distant objects. The most distant object known is a star cluster approximately thirteen billion light-years away from Earth, observed by the Hubble telescope using gravitational lensing<ref>http://news.bbc.co.uk/1/hi/sci/tech/3490657.stm</ref>. |