There are billions of stars in the Universe, but one alone dominates our celestial neighborhood, the Sun. It's so large that within its boundaries you could fit one million Earths, and so powerful that each second it churns out as much energy as one billion one-megaton hydrogen bombs.There are billions of stars in the Universe, but one alone dominates our celestial neighborhood, the Sun. It's so large that within its boundaries you could fit one million Earths, and so powerful that each second it churns out as much energy as one billion one-megaton hydrogen bombs.