A week ago I posted on  Death by a Gamma Ray Burst?   This week, I focus on another space invader, a large asteroid.  PBS has had several documentaries on this topic:   The Asteroid and the Dinosaur  and   Dinosaur Apocalypse . The scientific term for the above is  Impact Event .  The biggest Earth event might have been the  Big Splash , or the Theia Impact: This when our Moon was formed approximately 4.5 billion years ago. Theia, the mythical Greek Titan, was the colliding body, mother of Selene, the goddess of the Moon. The isotope ratios of lunar and terrestrial rock are identical. There are many theories, but one is that the Moon was formed by the tangential impact upon Earth of a body the size of Mars. Much of this giant-impact consensus emerged from a 1969 conference held at Kona, Hawaii.  Those who don't believe are called the agnostics. But our solar system is today quite different, and planet-sized impact neighbors are no longer present. 2 billion years ago an asteroid cal

Before I go into my Wednesday science topic, one note about COVID-19.  Of course, with so many tests now taken at home and not reported, surely the 100,000 or so new cases/day in the U.S. must be higher.   Here is one estimate by the University Columbia's Jeffrey Shaman : Shaman's research group turned to using models to estimate the "ascertainment rate" — the portion of real infections that were being captured in official case counts. That rate has fluctuated — at the end of 2020, they estimated one in four cases were being counted. During the omicron surge it was closer to one in six.   Now with the widespread availability of at-home rapid tests that aren't reported to health departments, Shaman thinks the true number of cases may be in the ballpark of eight times higher than case counts. In other words, instead of 100,000 new cases a day, the true number may be 800,000 cases per day. As terrible as that may sound, I think there is a silver lining.   So many hav