Using NASA’s Hubble and Spitzer Space Telescopes, an international team of astronomers have found nine of the smallest, faintest, most compact galaxies ever observed in the early universe–the building blocks of today’s larger, older galaxies. Composed of millions of brilliant blue stars, each infantile galaxy is one-hundredth to one-thousandth as large as our Milky Way galaxy. They formed about 12.5 billion years ago – just 1 billion years after the “Big Bang.”
Such galaxies are consistent with the conventional model of galactic formation, which holds that larger galaxies are formed when younger, smaller, less-massive galaxies merge. The sighting thus offers some much-needed support for the “hierarchical model,” which has become ever more contentious in recent years.