International Center for Radio Astronomy Research | 2018 Mar 13
Astronomers have discovered that all galaxies rotate once every billion years, no matter how big they are.
The Earth spinning around on its axis once gives us the length of a day, and a complete orbit of the Earth around the Sun gives us a year.
“It’s not Swiss watch precision,” said Professor Gerhardt Meurer from the UWA node of the International Centre for Radio Astronomy Research (ICRAR). “But regardless of whether a galaxy is very big or very small, if you could sit on the extreme edge of its disk as it spins, it would take you about a billion years to go all the way round.” ...
Cosmic Clocks: A Tight Radius-Velocity Relationship for HI-Selected Galaxies - Gerhardt R. Meurer et al
- Monthly Notices of the RAS 476(2):1624 (May 2018) DOI: 10.1093/mnras/sty275
arXiv.org > astro-ph > arXiv:1803.04716 > 13 Mar 2018