The Webb telescope finds surprisingly massive galaxies from the universe's youth

These images provided by NASA and the European Space Agency show six candidate massive galaxies, seen 500 million to 800 million years after the Big Bang. (NASA via AP)

CAPE CANAVERAL, Fla. — Astronomers have discovered what appear to be massive galaxies dating back to within 600 million years of the Big Bang, suggesting the early universe may have had a stellar fast-track that produced these "monsters."

While the new James Webb Space Telescope has spotted even older galaxies, dating to within a mere 300 million years of the beginning of the universe, it's the size and maturity of these six apparent mega-galaxies that stun scientists. They reported their findings Wednesday.