Bentonite, the name given to a group of industrially useful clays containing the mineral montmorillonite. Bentonite clays are primarily aluminum silicates, mixed with varying amounts of sodium, calcium, or magnesium. A major use of bentonite clays is in oil-well drilling mud, a mixture of water, bentonite, and chemicals used to cool the drilling bit and carry away cuttings from the well. Certain types of bentonite expand to several times their original volume when mixed with water; they are used as sealants in dams and concrete-lined canals.
When a star dies, it becomes a black hole. Once something passes through the it's gone for good, never to be seen or heard from again. If we lived next to a black hole, would it suck us in too?
Every November, the Leonid meteor shower fills the sky with "shooting stars." This year, the shower is expected to peak twice. Learn how Leonid and other meteor showers work.