![]() Even while it was still in its commissioning period, the telescope tracked an asteroid (Tenzing 6841) - the first time a space observatory has been able to do so. One of the main goals of JWST is to image planets around other stars, but it also will be able to observe small bodies such as asteroids and comets in our own solar system. The recently launched James Webb Space Telescope (JWST) may help us recognize some of these cosmic threats ahead of time. A gamma-ray burst could be coming at us with light velocity, and there would be no warning time. That seems safe enough, but it may not be, as the star’s spin axis is more or less pointed in our direction. One such star, WR-104 in the Gamma Velorum system, is 800 light-years away. Wolf-Rayet stars, which are at least 20 times as massive as our Sun, are capable of unleashing gamma-ray bursts. Such a cataclysm has been proposed as the cause of the Ordovician-Silurian mass extinction about 450 million years ago, which killed half of all animal life on Earth. Gamma-ray bursts produce almost unimaginable amounts of energy and can kill from much further away. (The late Devonian supernova was just 65 light-years away.)Īn even worse disaster would result if Earth got caught in the narrow “beam” of a gamma-ray burst resulting from the explosion of a massive star or the collision of two neutron stars. Luckily, the closest star in danger of going supernova any time soon is Betelgeuse, which is 640 light-years away. Nearby supernova explosions kill by showering Earth’s atmosphere with radiation that destroys our protective ozone layer. Supernova explosions have been linked to a minor mass extinction just 2.6 million years ago and to the late Devonian mass extinction about 350 million years ago, which resulted in the loss of three-quarters of all species on our planet. What followed were food shortages and drastic climate swings following the large impact causing the extinction of animals that rely on the plants directly or indirectly for food.Īsteroids are hardly the only danger from space. In the case of the dinosaur extinction, the initial kill mechanism was the ejection into the atmosphere of particles that block sunlight, preventing photosynthesis and leading to a major die-off of plants. Cosmic killersĪsteroid impacts can cause a succession of events that extinguish life. That resulted in the creation of Earth´s Moon and long-lasting magma oceans on the surface, which made our planet uninhabitable for some time. The largest impact event in Earth’s history occurred shortly after our planet formed, when it collided with a Mars-sized planetary body. Only a century earlier, the Tunguska meteoroid exploded over Siberia, flattening 80 million trees over an area of 2,150 square kilometers. In 2013, the Chelyabinsk meteoroid, as big as a six-story building, broke up over Russia and produced a blast stronger than a nuclear explosion. Many of the mass extinctions in our planet’s past were caused by meteorite impacts, and it remains a clear and present danger today. A fateful asteroid caused the demise of the (non-avian) dinosaurs 65 million years ago.
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