Disk of Dark Matter
Our solar system’s journey around and around the Milky Way may be more fraught with danger than we thought. Some Harvard scientists are now saying that dark matter in our galaxy may periodically hurtle comets towards the inner solar system as we periodically pass through a thin disk of the invisible stuff.
For many decades now some scientists have believed that crater evidence on the earth supports the theory that every 35 million years the earth is bombarded by comets. The culprit has often been thought to be an elliptically orbiting planet or star that gravitationally jostles comets in the far-flung oort cloud a light year away. No evidence has ever been found for this “Nemesis” star or planet but a recent publication in the journal Physical Review Letters claims it might in-fact be caused by the sun’s up-and-down journey through through the 35 light-year “thin” layer of dark matter that may exist in the central plane of our galaxy. It is this, they claim, that could be causing the comets to rain down on the inner solar system in such a predictable pattern.
This would be quite extraordinary if true but their premise of periodicity is far from a done deal. Sure there’s ancient craters on the earth but weathering and other natural processes make it difficult to find enough of them to be very confident that a 35 million year cycle of destruction is in fact real. While they’re at it, some solid evidence of this flattened disk of dark matter would be nice too. The European Space Agency’s Giaia mission will soon look for this evidence but in the meantime Nemesis might still be out there.