The ancient Greeks proved over 2,000 years ago that the Earth was round and figured out how big it was by using simple observations of the Sun. But how do people know this today? When you drop ...

Teaching our kids about the planet, its resources, and how to appreciate and protect them is one of the most important tasks ...

Bigger than a planet? Smaller than an atom? Size comparison videos are all the rage and may scratch a very old itch. By Jenny Marder Not long ago, my 7-year-old son looked up from a picture he was ...