The galaxy RX J2129-z95 has been detected by the James Webb telescope thanks to the gravitational lensing effect. Formed just 510 million years after the Big Bang, this remote galaxy features intense lines of oxygen and hydrogen.
It turns out to have a diameter of only 105 light years, that is, a thousand times smaller than that of our Milky Way. By studying its star-forming activity, astronomers deduce that the galaxy is highly active: it is forming stars at a rate of one solar mass per year.