Star Mass and Density


What makes a star shine bright?

Much earlier on—probably months ago now—I explained how something called the proton-proton chain generates massive amounts of energy within stars, and enables them to fuel whole solar systems. That’s the battery of a star.

We’ll address the proton-proton chain later, when we start talking about star life cycles. We’ve still got some talk about nebulas and interstellar space to go before we get that far. For now, what’s important is that the proton-proton chain depends on high density.

That is, stars will have the strongest batteries if they have very dense interiors. It doesn’t really matter how dense their middles and atmospheres are. But conditions in their cores must be very dense.

You’ll find, if you study stars closely, that there is a definite relation between their densities, masses, and luminosities. Continue reading

Binary Stars


We know how big stars are; they range from the size of the Earth to over a thousand times the size of the sun (which is in itself over one hundred times the size of the Earth). We know they’re huge.

But how massive are they?

Yes, that’s a different thing.

A pingpong ball and a golf ball are close to the same size, but a golf ball is much more massive—in that it has more stuff in it. A pingpong ball is hollow and easily tossed; a golf ball has more matter in it and will hit the ground with a harder thunk.

Stars are similar. They have a wide range of sizes, but nothing I’ve described thus far has told us about their masses. That is, how much stuff is in them? Are they like puffy gaseous balls, or are they more dense, like planets?

The best way to learn about stars’ masses is by studying binary stars. But what exactly are binary stars? Continue reading

The Building Blocks of the Universe


“The Building Blocks of the Universe.” When you put it that way, atoms sound less like a topic specifically for a chemistry class and more like something astronomers might discuss.

They really are. I’ve got a fantastic reason to include atoms under astronomy, and its name is stellar spectra.

We’ve encountered stellar spectra before in these astronomy posts. When I wrote about the spectrograph, an instrument astronomers use to study data, I talked about spectral lines. I also promised we’d come back to elaborate on that later.

We’re not actually going to talk about the spectrograph in this post. I’m saving that for another time. For now, I’m going to cover atoms in a little more detail.

That way, we’ll have a better understanding of how they interact with light later on—and that will help us understand the spectrograph. Continue reading

Einstein: General Relativity


Albert Einstein may have been the genius among physicists, but like all others before his time, he stood on the shoulders of giants.

Einstein did not propose that the sun was the center of the solar system; that idea was already widely accepted when he came around. He didn’t discover elliptical orbits; that distinction belongs with Johannes Kepler.

But Kepler never could figure out why planets orbit the sun in ellipses instead of circles. Even Isaac Newton, who at last identified gravity as the reason we stick to Earth’s surface, couldn’t explain what gravity was—only how it worked.

Einstein provided that explanation with his general theory of relativity. Continue reading

Newton’s Laws of Motion


It’s said that Sir Isaac Newton was sitting under an apple tree when an apple fell on his head, and that’s when all his discoveries began.

Personally, I doubt that story—just as I doubt that Galileo Galilei ever dropped iron and wooden balls off the Leaning Tower of Pisa. His goal would have been to show that both objects hit the ground at the same time. Unfortunately, wind resistance would have gotten in the way.

Regardless of how Newton discovered gravity, his scientific achievements are monumental. In fact, we recognize him today as one of the greatest scientists to ever live, second only to the famous Albert Einstein.

Newton’s revelation that gravity draws objects toward Earth changed the course of modern science. But what exactly did he find out? Continue reading

What Matters?


The simplest approach to chemistry is to start basic.

Not basic as in acids and bases, ha-ha…sorry, bad chemistry joke.

I mean basic as in, what the heck even is chemistry?

I admit that I’m better versed in astronomy than chemistry. I’ve studied chemistry for exactly one year of my life—last year, 12th grade. Astronomy, on the other hand, has been my strong suit and my passion for several years.

For me, these Wednesday posts are like a refresher course. I don’t actually remember everything I’ve learned. Good thing I bought a copy of the textbook.

So, I’ll start simple—because chemistry is the study of breaking complex things down to the simplest bits possible. It’s the opposite of astronomy. Astronomy studies huge, mind-blowing phenomena. Chemistry, on the other hand…is mind-blowingly small.

It’s the study of matter. Continue reading