The Average Star

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What the heck is the average star like?

We’ve talked about a lot of stars over the past few weeks. We’ve discovered the vast distances between the stars, looked more closely at what really makes a star bright, and covered all kinds of ways to classify stars—from their spectral type to their luminosity class.

Most importantly, we’ve looked at the H-R diagram, the diagram that classifies stars by their color, temperature, composition, and luminosity…and relates those properties with many other features stars have.

We know what kinds of stars are out there. We know they range from thousands of times smaller than the sun to thousands of times larger. We know they range from desperately faint to incredibly luminous. We know they come in all the colors of the rainbow.

But how many blue stars are there? How many small stars are there? Are most of them small, or are there about the same number of small stars as large ones? Continue reading

Stars and Proper Motion

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Recognize this constellation?

Well, at the time stamp of about 2000 AD (CE), I think you will. It’s one of the most famous constellations in the night sky.

Well, technically, it’s not a constellation at all.

It’s an asterism—a commonly recognized grouping of stars that isn’t actually official as a constellation. There are tons of asterisms that you no doubt recognize…the Summer Triangle, the Great Square of Pegasus, the Big Dipper.

That’s right. That mess of stars up there that keeps changing for some reason…that’s the oft-recognized Big Dipper, part of the constellation Ursa Major.

So why the heck are the stars moving? Continue reading

Where Are We?

In the 4th century B. C. E. (Before Common Era), scientists believed the Earth was the center of the universe. Before that, they were convinced the Earth was flat.

Now, most of us know that the Earth is not the center of the universe—nor is it flat. (Although there are definitely those who still believe we live atop a flat disk world, hurtling upwards through space.)

Not only is the Earth not the center of the universe, neither is the sun—and it’s not even the exact center of our solar system (you can read more on that here).

And if we zoomed out much farther and took a look at our galaxy from above—or below, take your pick—we’d find that the sun is not even near the center of its own galaxy.

It is, in fact, located in a small “spur” of stars just off one of the spiraling arms of the galaxy. And if our universe is in fact infinite—as the prevailing theory describes—then there can’t even be a center, so our galaxy is not the center of anything.

But what does all of this mean? Where exactly are we in the universe?

Continue reading