“If such a thing had happened once, it must have happened many times in our galaxy of a hundred billion suns,” wrote science-fiction author and philosopher, Arthur C Clarke about a mysterious celestial object —the work of an ancient alien civilization– that was detected flashing past Jupiter –proof that life not only existed outside the solar system, but also had scaled heights far beyond anything that man had achieved, or could hope to reach for centuries to come.
We are living through our Solar System’s twentieth, 223-250 million-year orbit of the Milky Way near the inner edge of the ephemeral spiral feature known as the Orion Arm or, less poetically, the Local Arm . The ghostly spiral arm is a concentrations of gas and dust where stars form, produced by disturbances within the Milky Way, or on occasions by a jolt from outside, such as a supernova. Life-threatening asteroids and comets are more frequent when a planetary system is crossing one of the galaxy’s spiral arms, where potentially deadly, dusty gas clouds congregate, stacking up in the equivalent of a hydrostatic jump.
Today’s “Insomnia File” episode offers two stories of cosmic insight. The first is about ”An Accident More Complex than the Universe” from former astrophysicist and hard science-fiction author Alastair Reynolds, who’s epiphany is found in his novel , Blue Remembered Earth — first of a trilogy which follows humanity’s development over many centuries and Paul Davies, The Demon in the Machine.
In 1936, in The Realm of the Nebulae, Edwin Hubble –who proved that objects previously thought of as “nebulae” were actually galaxies beyond the Milky Way–wrote that eventually, we reach the utmost limits of our telescopes where “we measure shadows and search among ghostly errors of measurement for landmarks that are scarcely more substantial.” Fast forward to today: a cold mystery gas from the center of the Milky Way, with its extreme astrophysics, has been detected “shooting like bullets” by an international team of astronomers –a phenomenon that has important implications for the future of our home galaxy.
It’s difficult to fully appreciate how much our picture of the universe has changed in the span of a single human lifetime. A century ago, the universe was viewed as static and eternal, consisting of one single “island” galaxy, our Milky Way, surrounded by vast, infinite, dark, and empty space. “With increasing distance,” said Edwin Hubble, “our knowledge fades, and fades rapidly. Eventually, we reach the dim boundary—the utmost limits of our telescopes.”
“In less than a hundred years, we have found a new way to think of ourselves,” observed Stephen Hawking. “From sitting at the center of the universe, we now find ourselves orbiting an average-sized sun, which is just one of millions of stars in our own Milky Way galaxy.” Some of the oldest stars in the universe are found in ancient globular clusters that orbit around the plane, the nucleus, of our home galaxy, which is circled by 150 globular clusters, harboring hundreds of thousands, and sometimes millions of stars, formed very early in the vast halo surrounding the embryonic Milky Way before it flattened to form the spiral disc.
