What Makes a Star Blue?

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Albireo is the distinctive double star in the head of the constellation Cygnus. You can find it yourself if you look for the Summer Triangle amid the dusty trail of the Milky Way across the night sky.

The brighter, orange star of Albireo is a K3-class bright giant. That means it’s just a few thousand Kelvins (Celsius degrees plus 273) cooler than the sun. But it’s also larger—70 times the sun’s radius—and that makes it brighter than you would expect.

The blue star, on the other hand, is a B8-class dwarf. It has only about 3.5 times the sun’s radius, although it’s hotter by about 7422 Kelvins.

Neither star in Albireo is particularly unusual. There are doubtless millions, even billions, of other stars similar to each one. But Albireo certainly offers us the most striking contrast. Bright blue and red stars don’t often appear so close together.

But what exactly gives these stars their distinctive colors? Continue reading

How Lightning Strikes

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There’s a saying that “lightning strikes whatever’s tallest.” But this is only partly true. Tall objects do attract lightning bolts, but there’s a second condition for lightning to strike: electrical conductivity.

Meaning, a lightning bolt will only strike an object that can become electrically charged.

There’s another common misconception out there, though the Google search I did reveals that knowledge of the truth is comfortingly widespread. If you were to catch sight of a lightning bolt, would you say it strikes upward or downward?

That is, does lightning start at the ground or in the clouds?

I heard from multiple reliable sources that lightning strikes from the ground up, but the video you’ll see below would seem to contradict that. I wasn’t satisfied with the results of my search, so I did some more digging.

Continue reading

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

The Reason for the Seasons

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As a born Californian, I never saw seasons this dramatically until I went to college in Flagstaff, Arizona.

I remember, in my first year here, when I was taking a walk around campus with a few friends. We passed over a riverbed where water was gently trickling along. Green grass and brush lined the banks. The sight absolutely captivated me. I had never seen anything like it, even in the springtime.

Then winter hit in all its blizzarding glory. At night, the temperature dropped below freezing. Snow fell in flurries that contrasted beautifully with the night. By morning, snow banks over a foot high lined the footpaths. To say nothing of the state of my winter jacket!

Summer in Flagstaff is hot. And I mean hot. It’s sweltering. Everyone crowds under the nearest tree. I experienced two days of it during orientation, and I never want to be here in the summer again.

Flagstaff’s autumn isn’t quite like the red and golden season depicted above. It pours. The rain sweeps down from the skies in torrents, soaking you through to the bone within minutes of being outside. Don’t think you’re safe under an umbrella. Better get some waterproof slacks to cover up those jeans, or you’ll be freezing in your classes all day.

I remember learning that my good blogging friend, the Momma, experiences the opposite seasons. When it’s pouring over here, it’s all green and sunny in Australia. When it snows here, she’s getting summer—I only hope it’s not as sweltering as it is in Flagstaff!

But why? Why should Australia have seasons that are opposite those in America? Continue reading