Galaxy I Zwicky 18 has been unmasked as being much older than previously thought, despite possessing a youthful appearance resembling galaxies typically found only in the early universe.

Hubble Space Telescope has detected faint, older stars within this galaxy, suggesting that the galaxy may have formed at the same time as most other galaxies.

Not only is I Zwicky 18 older than thought, it is also farther away than previously estimated. Hubble identified Cepheid variable stars in the galaxy for the first time. These massive stars pulse in a regular rhythm, which allow researchers to precisely measure their distance. It turns out that I Zwicky 18 lies 59 million light-years from Earth, almost 10 million light-years more distant than previously believed.

--NASA, ESA, and A. Aloisi (STScI/ESA) and SPACE.com Staff

Credit: NASA, ESA, and A. Aloisi (STScI/ESA)