Stars can be characterised by their absorption lines, which reveal their temperature and composition. There is more detail about this in two recent posts about the HR diagram and stellar classification. A similar approach can also be used to characterise entire galaxies but in this case the aim is to determine how quickly they are … Continue reading Red-Shift and the Age of the Universe
Why believe in the Big Bang?
It is often said that the reason why we “know” the Big Bang took place is because the Universe is expanding and if time were played backwards then everything would have started from the same point at the same moment in time. That moment, when everything started moving apart, is what we call the Big … Continue reading Why believe in the Big Bang?
Mr Tarrant's physbang 'blog 