Jogot

Observational history 

Hubble eXtreme Deep Field (XDF)

XDF size compared to the size of the moon - several thousand galaxies, each consisting of billions of stars, are in this small view.
XDF (2012) view - each light speck is a galaxy - some of these are as old as 13.2 billion years^[9] - the universe is estimated to contain 200 billion galaxies. 

XDF image shows fully mature galaxies in the foreground plane - nearly mature galaxies from 5 to 9 billion years ago - protogalaxies, blazing with young stars, beyond 9 billion years.

Throughout recorded history, several cosmologies and cosmogonies have been proposed to account for observations of the universe. The earliest quantitative geocentric models were developed by the ancient Greek philosophers. Over the centuries, more precise observations and improved theories of gravity led to Copernicus's heliocentric model and the Newtonian model of the Solar System, respectively. Further improvements in astronomy led to the realization that the Solar System is embedded in a galaxy composed of billions of stars, the Milky Way, and that other galaxies exist outside it, as far as astronomical instruments can reach. Careful studies of the distribution of these galaxies and their spectral lines have led to much of modern cosmology. Discovery of the red shift and cosmic microwave background radiation revealed that the universe is expanding and apparently had a beginning.^{[citation needed]}

History of the universe

According to the prevailing scientific model of the universe, known as the Big Bang, the universe expanded from an extremely hot, dense phase called the Planck epoch, in which all the matter and energy of the observable universe was concentrated. Since the Planck epoch, the universe has been expanding to its present form, possibly with a brief period (less than 10⁻³² seconds) of cosmic inflation. Several independent experimental measurements support this theoretical expansion and, more generally, the Big Bang theory. Recent observations indicate that this expansion is accelerating because of dark energy, and