Lunar Phases and Motion

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The lunar phases…who really understands ’em?

We see them all the time. When we look up at the moon in the sky, we’re bound to notice that it looks just a little bit different from the last time we saw it. It changes from a slivery crescent to a full circle, and then wanes back to the crescent phase again.

The moon has behaved the same way in the sky for billions of years, ever since a Mars-sized space rock collided with the newborn Earth and the debris collected into our own personal satellite.

For that long, the moon has watched over us and captivated scientists and amateur skywatchers alike.

But what are the secrets behind its monthly changes? Continue reading

Types of Mixtures

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The easiest way to explain mixtures in chemistry is to talk about food.

Think about mixtures in terms of cooking, and there isn’t much I need to tell you. A salad, like the one pictured above, is a mixture. So is chicken noodle soup. So is…hmm, so is lemonade.

I told you we’d be talking about lemonade soon.

Even air is a mixture—of different gases. Believe it or not, we don’t just breathe in oxygen. In fact, if we breathed in pure oxygen, it would be poisonous. We inhale a little bit of nitrogen, too.

A mixture is—by textbook definition—a physical blend of two or more substances. Continue reading