Just How Big Are Stars?

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Tell me about the stars you see in this image.

They look like billions of little pinpricks of light, right? It’s hard to imagine that each one of these is probably the size of the sun…or much larger. And the sun, by the way, is about 109 times Earth’s diameter.

So if you thought those stars were small…not so.

It makes sense that they would be very large. Their light reaches us from many light years away, with the nearest star 4.3 light years away and the most distant one likely trillions.

In order to radiate that far out and stay bright enough to speckle the night, they would have to be very luminous, and that means having a large surface area, even if they’re not particularly hot.

So how do we know how big the stars are? Continue reading

Improved Telescope Mounting

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So, any idea what this handy-dandy thing is?

Okay, so maybe I sort of gave it away in the post title…

I know what you’re about to say next. Why are we looking at a mount? What’s so special about a mount—isn’t the telescope itself more important?

And the fact is…I know where you’re going with that. The telescope is important, and without it, the mount would have no purpose. But without the mount, the telescope would be lost—it would have power, but nothing to do.

How’s that work? Continue reading

Precession

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We have a bit of a shorter post today—I thought precession warranted its own post, before I go on to talking about the ecliptic.

Precession is refers to the way Earth wobbles around on its axis, a bit like a top. This motion is caused by the sun and moon’s gravity tugging on the planet, and is key to understanding how many ancient cultures viewed the sky.

So what is precession, exactly? Continue reading