What Causes the Lunar Phases?

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We see it almost every night of our lives. For thousands of years, the greatest philosophers and astronomers alike have watched its face change and wondered why.

Step outside and observe the moon every day for a month and you will notice something fascinating. Over the course of the entire month, the moon will go through an entire cycle of phases—no more, no less.

But why?

The phases of the moon are something I’ve talked about before, but I wanted to spend some time on a few common misconceptions this time around and show you the truth behind the lunar phases. Continue reading

Life vs. Rocks: What Makes Them Different?

Welcome to my third “Science Answers” post! About a month ago, I sent out a post requesting science questions from all of you; you can find it here. This post addresses the third of the questions I was asked. If you have a question, you can ask it in the comments here or on that post, or ask it in an email. Or find me on Facebook!

Q: What is the division between the physical and life sciences? For example, why do we think of rocks in a different category than we do plants and animals? (asked by Katherine)

Okay, wow. Another great question! This one is almost as fundamental as gravity, which I answered earlier.

Gravity may be pretty much the singular reason why the universe works the way it does, but the difference between the physical and life sciences is an important distinction when trying to understand the world around us.

So let’s start with what we know. When you hear “physical science,” what do you think of?

 

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You might think of any number of things—but I’ll bet you that none of those things are alive in the traditional sense.

So, how about the biological sciences? What does that make you think of?

 

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Maybe plants…or cute animals?

Whatever you think of, I’m going to guess they’re all alive.

But what makes something alive or not alive? What makes zebras leap and run, whereas rocks are forever immobile? What makes these living beings different from a vast galaxy or the Pillars of Creation? Continue reading

What is Gravity, Anyway?

Welcome to my second “Science Answers” post! About a month ago, I sent out a post requesting science questions from all of you; you can find it here. This post addresses the second of the questions I was asked. If you have a question, you can ask it in the comments here or on that post, or ask it in an email. Or find me on Facebook!

Q: What is gravity? (asked by Simon)

Wow…great question. This is a question the greatest scientific minds have asked and tried to answer for centuries. It’s a question not even Stephen Hawking, the scientific genius of the century, has fully answered.

There are a few parts to the gravity question, and they have each been addressed one by one over time:

  • How does gravity work?
  • What is gravity?
  • Why does gravity work?

Isaac Newton stood on the shoulders of the giants before him—Aristotle, Ptolemy, Copernicus, and Kepler—and figured out how gravity works. But he was at a loss to explain what exactly this mysterious force was.

Einstein built on Newton’s work and came up with a theory for what gravity is—that is, distortions in space-time.

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We have yet to understand why gravity works. Why is space-time warped? Why do objects distort it as if it were the material of a trampoline? What exactly is the nature of space?

But, lucky for me, the question above specifically asks what gravity is. And that, I can explain.

The best way to do that is to turn one of gravity’s oldest tricks, one that has perplexed scientists and philosophers for thousands of years: What makes the planets move? Continue reading