Hubble taking advantage of gravitational lensing. Image: NASA, ESA and the HST Frontier Fields team (STScI)
With over 25 years in orbit under its belt, the Hubble Space Telescope (HST) is positively elderly for a space observatory. But far from sinking into obsolescence, Hubble has continued to capture incredibly beautiful images of the universe, revealing new vistas at the edge of time and space.Take, for instance, the most recent image series from the HST, which uncovered 250 previously undiscovered dwarf galaxies, which emerged about 600 to 900 million years after the Big Bang.These are some of the faintest, earliest, and most distant galaxies ever imaged; so dim that they would never have been seen at all, were it not for the gravitational lensing effects of three galaxy clusters that magnified their ancient radiance.The new observations were made by an international team of astronomers, led by Hakim Atek of the Ecole Polytechnique Fédérale de Lausanne in Switzerland. In addition to providing some premium space porn, the researchers said that these images can shed light on the epoch of reionization, one of the most transformative shifts in the universe's history.This epoch kicked off when the fog-like gas of the early universe began to clear, cooling and collapsing to form the first stars and galaxies. By about 700 million years after the Big Bang, space had evolved from being an opaque stew of high-energy particles to the mostly empty expanse, transparent to light, that we recognize today.According to Atek, dwarf galaxies were an instrumental factor in the epoch of reionization. "If we took into account only the contributions from bright and massive galaxies, we found that these were insufficient to reionize the universe," he said in a statement. "We also needed to add in the contribution of a more abundant population of faint dwarf galaxies."In other words, the HST has outdone itself again, bringing the era of reionization into sharp and captivating focus. The Hubble may be an oldtimer, but its discoveries remain as fresh and exciting as ever.
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