Context: NASA's James Webb Space Telescope (JWST) has discovered the earliest-known galaxy, JADES-GS-z14-0. This galaxy, remarkably large and bright, formed when the universe was just 2% of its current age. Until now, the earliest-known galaxy dated to about 320 million years after the Big Bang, as announced by the JADES team last year.
About JADES-GS-z14-0 galaxy:
- The galaxy 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 period in the first few hundred million years after the big bang where the first galaxies were born.
- These galaxies provide vital insight into the ways in which the gas, stars, and black holes were changing when the universe was very young.
- Early galaxies were formed in an environment that was denser and gas-rich than today. In addition, the chemical composition of the gas was very different, much closer to the pristine composition inherited from the Big Bang (hydrogen, helium and traces of lithium).
- The international team of astronomers used JWST to observe galaxies as part of the JWST Advanced Deep Extragalactic Survey (JADES) program.
- JADES-GS-z14-0 galaxy measures about 1,700-light years across.
- A light year is the distance light travels in a year, which is 9.5 trillion km.
- The galaxy has a mass equivalent to 500 million stars the size of our Sun and is rapidly forming new stars, about 20 every year. (It is dwarfed by some present-day galaxies such as the Milky Way is about 100,000 light years across, with the mass equivalent to about 10 billion sun-sized stars).
- The team also disclosed the discovery of the second oldest-known galaxy, from about 303 million years post-Big Bang.
- This galaxy, JADES-GS-z14-1, is smaller, with a mass equal to about 100 million sun-sized stars, measuring roughly 1,000 light years across and forming about two new stars per year.