Summary: Our home planet is made almost entirely of recycled materials. The iron in the core, the silicon and magnesium in the mantle, the nitrogen and oxygen in the air were all made in the hearts of stars, then expelled into space when the stars died. Many of these elements came from the heart of a supernova — a massive star that blasted most of itself to bits in a titanic explosion. A future stellar recycling center is in good view this evening. Antares, the brightest star of Scorpius, is to the lower right of the Moon at nightfall and sets a couple of hours later. Antares is at least 15 times as massive as the Sun. The pressure in the centers of such stars makes them extremely hot. The heat allows chemical elements to “fuse” together to make heavier ones. So by the end of its life, Antares will have built up an iron core, surrounded by layers of oxygen, carbon, silicon, and other elements. And when Antares explodes, the extreme heat of the supernova will produce elements that are even heavier than iron — elements like lead, uranium, and gold. The explosion will blast these elements outward at a few percent of the speed of light. Eventually, some of the debris may ram into clouds of cold gas and dust. The impact will squeeze the clouds, causing them to collapse and give birth to new stars and planets. These newborn objects will be seeded with the elements created by the supernova — elements recycled from an exploding star. Script by Damond Benningfield, Copyright 2012 For more skywatching tips, astronomy news, and much more, read StarDate magazine.
