Geissler Tube, an electron tube that is used to study the behavior of gases. It was invented in the 1860's by Heinrich Geissler, a German. The tube is made of glass, with an electrode at each end. Electricity is passed through a gas under low pressure within the tube; the color of the light produced depends on the kind of gas. Geissler tubes are used in physics demonstrations in high schools and colleges. They were forerunners of neon lights.
Nebulae are collections of dust and gases scattered across the galaxy. They're the sites where stars are born and what's left behind after they die.
Albert Einstein was a pretty smart guy. When you look up the word "genius" in the dictionary, so the saying goes, it's a pretty safe bet you'll see Einstein's mug. Think you’re smart enough to take on a quiz about the famed thinker?