16/01/2025
A century ago, our understanding of the universe exploded.
By observing a Cepheid variable star (which pulse at a rhythm directly tied to their luminosity) called V1, astronomer Edwin Hubble determined that our galaxy wasn't the whole universe.
Our universe, rather, is full of countless galaxies beyond our own Milky Way.
His observations of V1, nestled inside the Andromeda "nebula", confirmed that Andromeda is actually an entire galaxy itself, located over two million light-years away. That distance far exceeded anything in our own Milky Way, and led Hubble to the jaw-dropping realization that the universe extends far, far beyond our galaxy.
Edwin Hubble went on to measure the distances to many galaxies beyond the Milky Way. The velocities of those galaxies also allowed him to determine that the universe is expanding.
In the hundred years since, the telescope named for Edwin Hubble continues his legacy, measuring and observing our massive, expanding universe.
Read more about this benchmark discovery and anniversary: https://go.nasa.gov/4h7erxq
Image credit: NASA, ESA, Hubble Heritage Team (STScI/AURA); Acknowledgment: R. Gendler