Archives of Ask A Scientist!

About "Ask A Scientist!"

On September 17th, 1998 the Ithaca Journal ran its first "Ask A Scientist!" article in which Professor Neil Ashcroft , who was then the director of CCMR, answered the question "What is Jupiter made of?" Since then, we have received over 1,000 questions from students and adults from all over the world. Select questions are answered weekly and published in the Ithaca Journal and on our web site. "Ask A Scientist!" reaches more than 21,000 Central New York residents through the Ithaca Journal and countless others around the world throught the "Ask a Scientist!" web site.

Across disciplines and across the state, from Nobel Prize winning scientist David Lee to notable science education advocate Bill Nye, researchers and scientists have been called on to respond to these questions. For more than seven years, kids - and a few adults - have been submitting their queries to find out the answer to life's everyday questions.

Previous Week's Question Published: 6 June, 2002 Next Week's Question
Dust (and lots of it) makes the world go 'round
What causes the earth to rotate and why?

Dear Rotation Ruminator,

The main reason the Earth is rotating now, is that there is nothing to stop it. The Earth and everything on it, including you, me, the ocean, and the atmosphere is spinning, revolving, and moving through the emptiness of space. Our planet moves through a vacuum. There is hardly anything out there to drag on us. The air is held here by gravity. Above it, space gets emptier and emptier.

The Earth got started spinning a little over four and a half billion years ago, when it formed from cosmic dust. Tiny as they may be, specks of dust have gravity. Check out a dusty shelf sometime. The Earth isn't just pulling the dust down. The dust is, ever so slightly pulling the Earth up. (Weird, yes?) The particles left over from the explosions of distant stars pulled themselves together and formed our Sun, the asteroids, the other planets and moons, and our own Earth.

The Earth and the other planets are enormous balls of deep-space dust. The dust particles came from all different directions in space. We can see stars in every direction, and with sensitive enough telescopes, we can see exploding stars in every direction. The process of cosmic dust-making is still going on. When the Earth formed, the dust didn't come together exactly evenly -- almost, but not exactly. This unevenness made the Earth take on a slight spin.

Try this. Put a quarter on a smooth table. Now, slide pennies or dimes right at the quarter, bumping and nudging it. Watch the picture (the eagle or George Washington). You'll notice that it's very hard to bump the quarter without making it rotate just a little bit. The same thing happened with the dust. As it came together it took on a little spin, a little rotation. And, that motion is still with us today. It makes the world go round. Whee!

Related Questions