Yup, It's Earth Day

Earth Day is April 22 every year. On average (jumping over leap years and such), between subsequent Earth Days our planet moves about 940 million kilometers (580 million miles), the circumference of its orbit around the Sun. That means it’s faster—way faster—than a speeding bullet: about 30 km/sec (18 miles/sec)! Typical rifle bullets travel 1-2 km/sec, so the Earth outpaces them handily.

It’s not a small world after all. The surface area of the Earth is about 510 million square kilometers, or 197 million square miles. It’s not a perfect sphere, but if it were, using the surface area to find the Earth’s diameter would give you a ball 12,742 km (7,900 miles) across.

Earth has something no other planet we know of has: a lot of water on the surface. It’s about 71 percent water by area, dominated by the Pacific Ocean, which covers a staggering 155.6 million square km (60 million square miles) of the surface. That’s nearly a third of the planet.

Water exists naturally in all three physical states on Earth’s surface: solid (ice), liquid, and gas (water vapor). Due to a peculiar property of water—called its triple point—it can even exist in all three states at the same location and time. So now when things go wrong, you can say, “Well it could be worse: It could be raining and snowing and steaming!”

So there you go, just a few tidbits about our home.  Enjoy the day.