The observable Universe is populated by between 1 trillion and 3 trillion galaxies, almost 10 times more than previously estimated.

A team led by Christopher Conselice at the University of Nottingham, UK, estimated this number using various telescope surveys that revealed evolving galaxy abundances since the time when the Universe was only about 600 million years old. The count included rare massive galaxies and smaller dwarf galaxies that can be impossible to see in the distant Universe with current telescopes.

The findings suggest that many more galaxies, especially faint and small ones, remain to be detected by projects such as the European Space Agency's upcoming Euclid mission.

Astrophys. J. in the press; Preprint at http://arxiv.org/abs/1607.03909 (2016)