“You know, our sun looks just like thousands of other stars in the sky. You’d never guess that there are planets going around it, and that one of those planets has people who consider themselves very intelligent. There would be no way of knowing that,” said Cornell University icon, astronomer Carl Sagan, in a 1973 interview with Rolling Stone, long before Michel Mayor and Didier Queloz announced the first discovery of a planet outside our solar system, an exoplanet, orbiting a solar-type star in our home galaxy, the Milky Way in 1995. The planet, 51 Pegasi b, a gaseous ball comparable with the solar system’s biggest gas giant, Jupiter was detected at the Haute-Provence Observatory in southern France, using custom-made instruments.
“So they’re kind of like dark matter,” said paleontologist David Jablonski of the University of Chicago about the sanctuaries, the “refugia” that have never been found in the fossil record, but sheltered the shell-shocked and decimated species of Earth’s past mass extinctions until they were able to repopulate the planet in ensuing eons.
In 2018, an international team of astronomers proposed that around 8 billion to 10 billion years ago an unknown massive dwarf galaxy dubbed the “Sausage” –with a total mass in gas, stars and dark matter more than 10 billion times our sun– crashed head-on into our Milky Way galaxy, ripping the dwarf to shreds, leaving its stars moving in long, narrow needle-like radial orbits. This defining event in the early history of the Milky Way reshaped the structure of our galaxy into its warped, twisted shape shown above, with the Sausage debris scattered around the inner parts of the Milky Way, creating the ‘bulge’ at the galaxy’s center and the surrounding ‘stellar halo.’
Our home galaxy, the Milky Way, is only one of a 150 billion galaxies visible to our telescopes, and, like all galaxies, is cloaked in a huge halo, that itself enshrouds a mystery. In 2018, HaloSat, a minisatellite designed to probe at the X-rays emitted by the Milky Way’s heated halo, the circumgalactic medium (CGM), was launched into space to search for atomic remnants of the leftover baryonic matter –believed to be missing since the universe’s birth nearly 14 billion years ago.
Planet Earth Report” provides descriptive links to headline news by leading science journalists about the extraordinary discoveries, technology, people, and events changing our knowledge of Planet Earth and the future of the human species.
The human experience on our pale blue dot “has lasted for less than 10 one-billionths of cosmic history surrounded by a vast lifeless space, yet we humans are congratulating ourselves,” says Peter Brannen author of Ends of the World about the current reign of humans recently named the Anthropocene –the period dating from the Atomic Age of the 1950s during which human activity has been the dominant influence on climate and the environment– “on an unearned geological legacy before we’ve proved ourselves capable of escaping the next century with our lives. And, besides, most of our proudest creations—whole cities and manufactured landscapes—will be destroyed by the ceaseless destruction of tectonics and erosion…many of the synthetic markers proposed to delineate the Anthropocene will not survive the insults of deep time.”
“Planet Earth Report” provides descriptive links to headline news by leading science journalists about the extraordinary discoveries, technology, people, and events changing our knowledge of Planet Earth and the future of the human species.
