- NASA’s James Webb Space Telescope (JWST) has spotted the earliest-known galaxy, one that is surprisingly bright and big considering it formed during the universe’s infancy — at only 2% of its current age.
- JWST is observing the galaxy as it existed about 290 million years after the Big Bang event that initiated the universe roughly 13.8 billion years ago.
- This period spanning the universe’s first few hundred million years is called cosmic dawn.
- The discovery was made by the JWST Advanced Deep Extragalactic Survey (JADES) research team. This galaxy, called JADES-GS-z14-0, measures about 1,700 lightyears across.
- It has a mass equivalent to 500 million stars the size of our Sun and is rapidly forming new stars, about 20 every year.
- Before JWST’s observations, scientists didn’t know galaxies could exist so early, and certainly not luminous ones like this.
- JWST is showing that galaxies in the early universe were much more luminous than we had anticipated.
- Until now, the earliest-known galaxy dated to about 320 million years after the Big Bang, as announced by the JADES team last year.
- It is quite big for such an early galaxy, it is dwarfed by some present-day galaxies.
Early Universe
- Star formation in the early universe was more violent than today, with massive hot stars forming and dying quickly, and releasing tremendous amounts of energy through ultraviolet light, stellar winds and supernova explosions.
- The luminosity of early galaxies was widely attributed to supermassive black holes in these galaxies gobbling up material.
- That appears to have been ruled out by the new findings because the light observed is spread over an area wider than would be expected from black hole gluttony.
- Our Milky Way is about 100,000 light-years across, with the mass equivalent to about 10 billion Sun-sized stars.
Dig Deeper: Read about the Big Bang Theory and Supernova explosions.
