Skytalk

This Thursday is Halloween…and Dark Matter Day! Dark matter-themed events are being organized by labs and institutions around the world doing this research. They range from live webcasts with researchers to dark matter scavenger hunts to a Reddit AMA. Find a sortable list at www.darkmatterday.com/events-list Scientists believe that dark matter, which we have so far only detected through its gravity-based effects in space, makes up about a quarter (26.8 percent) of the total mass and energy of the universe, and something that is driving the universe’s accelerating expansion, which scientists call dark energy, accounts for another 68.3 percent. The ordinary matter, like stars and planets and galaxies, makes up just 4.9 percent of the total mass and energy of the universe. So there’s a BIG part of the universe that we don’t know much about. We’re not sure if dark matter is made up of undiscovered particles, or if it can be explained by tweaking the known laws of physics. Its makeup