It’s 2010, and NASA scientists are busy analyzing data about our galaxy, the Milky Way, harvested from the Fermi Gamma-ray Space Telescope. It’s all in a day’s work for the astronomers, but then they spot something different. The researchers see two massive bubbles in the Milky Way, each extending for 25,000 light-years. It’s a head-scratching moment: just what are the scientists looking at?
We’ll get back to the best explanation we have for this startling new phenomenon in our corner of the Universe later. But first let’s take a look at how scientists have been exploring – and learning about – our galaxy over the centuries. It’s a fascinating story but one with no conclusion in sight. There’s just so much more still to learn.
Get out of the light-polluted cities and look up into the sky on a clear night and it’s not too hard to spot the bright cloud-like mass of billions of stars that make up the Milky Way. Our Sun is just one of the estimated 100 billion to 400 billion stars in our home galaxy. Then there are an estimated 100 billion planets (at least) as well.