Why Does the Earth Hum?
Seismometers always record periodic noise. Once mysterious in nature, we attribute Earth hum to ocean waves crashing into continents, vibrating like a bell.
Properties of Earth
Shape of the Earth: The Oblate Spheroid
Earth is not a perfect sphere. In fact, it’s in the shape of an oblate spheroid. Earth shape bulges at the equator and flattens at the north and south pole.
Chandler Wobble: Why Earth Wobbles Like a Toy Top
Earth spins on its axis of rotation. But it doesn’t spin perfectly. Like a toy top, it wobbles when it spins. This displacement is the Chandler Wobble.
What is Earth’s Escape Velocity?
The escape velocity of Earth (11.186 km/s) is the speed at which a free object must travel to escape into space from the planet’s gravitational pull.
Why Do We Have Seasons?
Because the Earth is tilted on its axis, it’s why we have seasons. When Earth receives more sunlight on one side, it’s summer. And vice versa for winter.
Earth Rotation: The Day-Night Boundary
As the Earth spins, the sun always shines on one side which gives it sunlight. When you’re facing the sun, it’s daytime. But when you’re not, it’s night.