Here, I use a particular type of mental picture to contemplate the possible extent of the biological universe. The idea is that at various levels of spatial scale we can use green to depict entities with life. Such entities could be planets with life, stars that have planetary systems with life, or galaxies that include one or more such planetary systems. Whatever the extent of the biological universe, another question is: what form does it take? A pessimistic answer is that we have no idea because so far we only have a sample size of a single inhabited planet. However, I advocate a more optimistic view by recommending what I call Copernican biology. This is the view that life on Earth is more likely to be ordinary than special. I consider which laws of science should apply to the biological universe and which should not. I then ask to what extent alien life-forms would be expected to resemble terrestrial ones in their construction, at both cellular and morphological levels. I end by outlining a view of the extent and nature of the biological universe that I call the Huge hypothesis.