The galaxy shows a high rate of star formation, so it releases its peak radiation at the vacuum ultraviolet part of the electromagnetic spectrum, near the 121.567 nm (1,215.67 Å) Lyman-alpha emission line due to the intense radiation from newly formed blue stars, hence it is classified as a Lyman-break galaxy; high-redshift starburst galaxies emitting the Lyman-alpha emission line.

[5] EGS-zs8-1 was born 670 million years after the Big Bang, during the period of reionization, and it's 15 percent the size of the Milky Way.

[6] The age of EGS-zs8-1 places it in the reionization phase of creation, a time when hydrogen outside the galaxies was switching from a neutral to ionized state.

[7][8] In 2013, Yale astronomer Pascal Oesch spotted an unexpected bright object while looking at Hubble Space Telescope images.

[7] Oesch and his colleagues at Yale and the University of California, Santa Cruz announced the find, which was named EGS-zs8-1, in May 2015 surpassing the previous record for oldest galaxy by about 30 million years.