13 530 million years – 13.5 kilometres
The dark ages. Stars or galaxies have not been born yet. The cosmic microwave background has cooled to 55 K or -218 °C
After the formation of the background cosmic radiation there is no stars or galaxies in the universe as yet. They will be formed only later from the hydrogen and helium gases. Before they are born, the universe would appeared to our senses as totally dark. At the distance of redsift z = 20, the background radiation corresponds to the temperature of 55K, or the radiation of an object at a temperature of -218 °C. Thus, the original universal dark red glow has cooled to an invisible far-red, dim radiation of the deep-frozen universe – and there is no stars in the sky.
Image: There are no stars in the universe.