Awesome Scishow

For the curious among us, SciShow host Hank Green is here to explain the wonders of fluorescence and phosphorescence. Along the way, you’ll learn why your teeth glow under black light, how different wavelengths of light travel, and how fluorescence has become so important in science and medicine.

The Earth’s lone moon is very important to the way the world works, affecting everything from the ocean tides, to the regularity of our seasons and the length of our days. But what would happen if another similar asteroid got pulled into the Earth’s orbit? SciShow explores some of the potentially serious implications.