A New View Of The Milky Way

A Dynamic, Complicated, Bubble-blowing Wild Child: Meet Our Galaxy All Over Again

- Kulvinder Singh Chadha

Like a baby, our galaxy ate a lot and grew big. And like a person, it’s constantly changing. Work done by many astronomers shows its all-consuming past, while new results from the European Space Agency’s (ESA) Gaia spacecraft show its complex dynamics. Alongside this are new observations of the galaxy we call home.

The popular view of the Milky Way is that it’s a spiral galaxy with arms of stars, dust, and gas radiating out in a disc around 120,000 light-years across, with a central galactic bulge of 10 to 12,000 light-years in diameter. Our Solar System lies 26,000 light-years from the Galactic Centre – between the bulge and the disc edge. Yet there are more elements to the galaxy’s structure than this. Spitzer Space Telescope observations in 2005 showed that the Milky Way is a barred spiral – its central region is bar-shaped. And the galaxy is peppered by a spheroidal halo of globular clusters.

Around 150 in total, these are gravitationally bound formations containing hundreds of thousands of very old stars. The Milky Way also has numerous satellite galaxies, some of which are merging with it, while others are having their gas stripped by its gravity. Then there’s the bubbles – or lobes – that emanate from the Galactic Centre and the galaxy’s large dark matter halo.