Beetle v. Geoid. If the earth were a perfect sphere, he says, it would not be stable on its axis. The “smallest beetle crawling over it would change the axis of rotation in relation to markings ...

A rotating sphere makes contact with both the driven disc and the wheel. When the rotation axis of the sphere is at 45° between the disc and the wheel, it provides a one 1:1 transmission ratio.

Save guides, add subjects and pick up where you left off with your BBC account. Earth’s axis of rotation is tilted, as you can see from this illustration. This means that day and night are not ...

Dramatic ice melt due to climate change may move the locations of Earth's geographic poles in the coming years, a new study finds. As ice sheets melt and ocean mass gets redistributed around the ...