Luminosity and Distance. Luminosity and how far away things are. In this class, we will describe how bright a star or galaxy …
Astronomers regularly talk with confidence about how far away stars and galaxies are, but how is it possible to calculate such …
Scientists use a "cosmic distance ladder" to determine how far away things are in the universe. This method depends on …
Scientists have estimated the age of the Universe to be 13.73 billion years old (with an uncertainty of about 120 million …
This animated video illustrates how far a light second, minute and year are. NASA-JPL-Caltech. For much greater distances …
更多内容请点击：The Farthest Visible Reaches of Space - Ima…