From our own perspective on Earth, we’ve identified the presence of spiral arms.
By viewing the Milky Way in infrared wavelengths of light, we can see through the galactic dust and view the distribution of stars and star-forming regions behind them. As revealed by the 2 micron all-sky survey (2MASS), the densest collections of galactic dust can be seen tracing out our spiral arms. (Credit: 2MASS/IPAC/Caltech & UMass)
However, being stuck within the Milky Way itself, we exclusively view it edge-on.
The European Space Agency’s space-based Gaia mission has mapped out the three-dimensional positions and locations of more than one billion stars in our Milky Way galaxy: the most of all-time. Looking toward the center of the Milky Way, Gaia reveals both light-blocking and luminous features that are scientifically and visually fascinating. (Credit: ESA/Gaia/DPAC)
Even our best spaceborne views leave much ambiguity in our galaxy’s overall structure.
