Our galaxy not only isn’t stationary, but different parts are accelerating at different rates.
When we think about the Universe as a whole, the accelerations that objects experience from our perspective are overwhelmingly due to the expansion of the Universe. Nearby, however, it’s the local gravitational effects of nearby masses that dominate. Within our own Local Group, we’ve been able to discover that the Milky Way is not some quiet, massive spiral just going about its own business, but rather that it’s being tugged in a variety of ways from the large masses around it, including a nearby galaxy that was only discovered in very recent years: Antlia 2.
This is one of the most exciting detective stories we’ve gotten to uncover in recent years, as the resolution of this mystery showcases how improved, high-resolution data taken over long periods of time can enable us to witness galactic changes, directly, on the timescale of a single human lifetime. Here to walk us through what we know, how we know it, and what comes next is Prof. Sukanya Chakrabarti of the Rochester Institute of Technology, and I think you’ll really enjoy what turned out to be a deep and far-ranging conversation about astronomy right in our own cosmic neighborhood!
Starts With A Bang is written by Ethan Siegel, Ph.D., author of Beyond The Galaxy, and Treknology: The Science of Star Trek from Tricorders to Warp Drive.