The galaxy cluster MACSJ0717.5+3745. (ESA/NASA)

The Hubble space telescope has been used to spy galaxies that formed just 600 million years after the big bang. These represent the faintest, most ancient galaxies ever spotted by the Hubble.

[This distant galaxy looks like a flaming ring in space]

The results, which will be published in an upcoming edition of the Astrophysical Journal, relied on a phenomenon known as gravitational lensing. Astronomers took advantage of cosmic "lenses" formed by the massive gravity of distant galaxies, which bend light in strange ways. When we look toward these lens-like galaxies, we can see the light of galaxies sitting far beyond them -- magnified. Scientists are increasingly relying on these natural lenses to spot star systems so far away that we're seeing them as they were billions of years ago.

The 250 dwarf galaxies spotted were there just 600 to 900 million years after the big bang, and the light from those galaxies took 12 billion years to reach the Hubble.

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