Transcript: Astronomers have used deep field observations, pointed surveys with large telescopes in the Hubble Space Telescope, to estimate the number of galaxies in the universe. This is based on a sampling technique. Astronomers do not have to survey the sky in every direction. They use a small pencil beam survey punching deep through the observable universe to count the number of galaxies in a few directions and then multiply up to get the total number of galaxies on the full coverage of the sky. In a region that’s about the size of the head of a pin held at arms length the Hubble Space Telescope can count three thousand galaxies to the limit of its observation, ten billion times fainter than the eye can see. Multiplying this across the area of the sky yields an estimate of sixty billion galaxies in the observable universe each with billions of stars, so the total stellar content of the universe is ten to the power twenty stars, a hundred billion billion stars in the universe.