Spots on the Sun

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Have you ever looked at the sun, and seen something like this?

Now, before you decide to look at it right now and see what you see, it’s my responsibility as an amateur astronomer to remind you of the safety risks. Focusing your eyes on the sun is dangerous—there’s a reason our eyes automatically flinch away.

How dangerous, you ask? Dangerous enough to burn and even scar your retinas, permanently damaging or even destroying your vision.

Yes, I’m serious.

Now, all this is not to turn you off solar observing entirely. There are safe—and cheap—ways to look at the sun, and see its spots.

But what exactly are sunspots?

Continue reading

Our Sun: The Corona

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When we observe our sun’s corona, we discover something odd.

It’s really, really hot.

But…wait a second. How is that odd? Shouldn’t the sun be hot?

Well…yes. It should, and it is. Its surface temperature is almost ten thousand degrees Fahrenheit, and its core is many times hotter. But there’s a basic law of physics that says energy flows from hotter regions to cooler regions.

The core and photosphere (the visible surface) follow this rule. Even the chromosphere, the lower atmosphere, does as it’s told. But the corona is made up of gases that are hotter than the chromosphere.

What’s up with that? Continue reading

The Hubble Space Telescope

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The Hubble Space Telescope is one of the most famous telescopes in the world.

Oops, excuse me—one of the most famous telescopes built.

Hubble, after all, is certainly not in this world. Unless you call the universe the “world,” it’s about as far from being in this world as you can get. It’s in space.

Hubble isn’t that different from an ordinary, ground telescope. It’s only as big as a bus. There are bigger optical telescopes. Its mirror is 2.4 m across—hardly an achievement by modern-day standards.

Palomar Observatory, which was the biggest telescope in the world when it was built, has better optics than Hubble, meaning its images are a bit crisper.

But that doesn’t keep astronomers from continuing to use Hubble. In fact, if you want to use Hubble, you have to get in line—it hardly has time to complete all the projects astronomers ask of it, even observing the night sky 24/7.

So why is Hubble so useful? Continue reading

Interferometry

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Imagine you have an image like this. This object is faint and faraway, so you can’t make out much more detail. You know that other stars like it—closer, brighter stars—have looked like this and turned out to be two stars, nestled very close together.

How do you figure out what you’re looking at? How do you increase the resolving power on your telescope so that you can make out more detail?

A telescope’s resolving power is limited by its size. Bigger telescopes can make out more detail on faraway objects—that’s because they can gather more light. But now, we can make telescopes that are so big their size doesn’t limit their resolving power anymore.

The atmosphere does.

We obviously can’t change the atmosphere. So how do we get around this particular predicament? Continue reading

Einstein: Space-Time Curvature

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When you hear about “space-time,” it’s just a way to say that space is related to time. And the curvature of space-time, as Albert Einstein predicted, is the way space and time alike literally bend around a mass such as the Earth or the sun.

That’s what’s diagramed above. This is a three-dimensional concept diagram of the way space sort of “clings” to an object. Notice the way it sort of tightens up when you get close to Earth? And because time is part of this whole equation…time sort of tightens up, too.

I assume that explains the “twin paradox,” as it’s called. That’s where the space-traveling twin returns home to Earth younger than their Earth bound twin.

Why? Seems to me it’s because time was tighter and passed faster on Earth, while it spread out and passed a bit slower for the traveler. (Don’t quote me on that, I just guessed that from this diagram.)

Einstein figured all this out. But scientists need evidence. Trusting Einstein’s genius wasn’t enough for them. How did they accept relativity as fact? Continue reading

Galileo and the Telescope

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When you hear the name “Galileo Galilei,” what immediately comes to mind?

If you thought, “inventor of the telescope,” you’re not alone. I also wouldn’t be surprised if you thought “condemned by the Inquisition for believing the Earth orbited the sun.”

But neither of these are true. If you’ve been following my more recent astronomy posts, you probably realize why—in Galileo’s time, people already knew that the Earth moved around the sun.

The idea that he invented the telescope is more understandable…but, again, it’s not true.

So what is true about Galileo, and how did he contribute to our understanding of astronomy? Continue reading

Johannes Kepler and Planetary Motion

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Thales and Pythagoras suggested that the natural world could be understood. Aristotle dared to imagine what was beyond the Earth. Plato encouraged thought about the universe, even if he did take astronomy one step forward and two steps backward.

Copernicus followed in Ptolemy’s wake, devising the revolutionary heliocentric (sun-centric) model of the universe. Tycho Brahe may have (incorrectly) rejected that model, but he did make some of the most detailed night sky observations yet.

What’s more, by Johannes Kepler’s time, Tycho had cast doubt on the idea of uniform circular motion that had plagued astronomy for centuries.

At last, the world was ready for a more mathematical take on a question that had confounded philosophers, mathematicians, and classical astronomers alike: how do the planets truly move through space?

By standing on the shoulders of giants, Johannes Kepler was finally able to devise his three laws of planetary motion, which are still the leading mathematical theory today. Continue reading

Tycho Brahe, the Observer

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It is surprisingly difficult to find a flattering image of Tycho Brahe.

Honestly. Do me a favor and do a Google image search for the guy. It’ll come up with all sorts of disfigured images, mostly because his nose got messed up in a sword fight…

I know what you’re thinking. A classical astronomer in a sword fight? Suddenly these people seem less like heroes of modern-day science and more like human beings with lives of their own.

Tycho certainly fits the trend. He’s known for being quite the unpopular sort. Bad-tempered and vain, there were few who respected him for more than just his astronomical accomplishments—and even those were few.

So why is he even important, then?

Continue reading

The Copernican Revolution

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Nicolaus Copernicus lived from 1473-1543, a time when rebellion against the Church was at its height. And unfortunately for the astronomy of the time, it had gotten inextricably tied up with Christian teachings.

In that time, heaven and hell weren’t just parts of our personal religions and beliefs—the Church held some of the highest authority over the land, and questioning heaven and hell just wasn’t done.

The way astronomers of the time pictured the universe fell right in sync with the heaven and hell geometry—Earth was the imperfect center of the universe, with hell nested deep below. Heaven was a place of perfection, and it was where all the heavenly bodies—the moon, sun, planets and stars—all moved.

Problem was, the Ptolemaic model of the universe really couldn’t explain detailed observations. It used epicycles to explain why the planets moved backwards sometimes. And no matter what people tried, they couldn’t get it to be accurate…

But then along came Copernicus, who would be the first to challenge the Ptolemaic universe and be believed. Continue reading