When you look up into the sky on a clear night away from the glare of the city, you see trillions upon trillions of stars.
Thousands of years ago, the classical astronomers saw the same thing you do today—except perhaps a little different, due to the ever-changing cosmos. And, like you, they weren’t satisfied with just looking. They wanted to know what was out there.
For hundreds of years, they developed model after model to explain why the stars seemed to orbit the Earth and why certain objects in the sky—which they named planets—seemed to wander backwards from time to time.
Tycho Brahe, an astronomer known mainly for what he got wrong, dismissed the idea of the Earth orbiting the sun because he could detect no parallax between the stars.
If he had been able to measure parallax, he might have realized that the universe was much larger than any of his fellow classical astronomers imagined.
So what is parallax…and how can it help us measure the distances between stars? Continue reading
When you hear the word “weather,” you probably think of clouds and lightning bolts and rainstorms. Maybe, if you live in particularly high elevation or latitude, you think snowstorms or even blizzards.
We humans are used to these weather patterns. They’re the norm here on Earth. But would you be surprised to hear that the sun has weather of its own?
The sun doesn’t have clouds. Electricity doesn’t crackle through its atmosphere and build up as lightning. Its surface sits comfortably at about 5800 K, which is 9980°F and 5526°C—so it doesn’t even get close to cold enough for rain or snow.
So what kind of weather does the sun have? Continue reading
Ask any climate scientist how we should power our world without fossil fuels, and they’re bound to tell you about wind and solar power.
You might be surprised to know that both of these come from the sun. Solar panels collect the sun’s energy directly, but we wouldn’t even have wind if not for the sun.
Why? Because in order to move, you need energy. And not just you. I’m talking about every speck of material on Planet Earth that shifts an inch. It’s because it has energy.
That energy can come from a lot of places. Earth is still a dynamic world with a hot interior, but it’s not hot enough to sustain all the life and other movement on its surface. A lot of our planet’s energy comes from the sun.
But here’s the big question. How the heck does it get here? Continue reading
You probably recognize this image. You see something like it whenever you look up at the sky. Some days are clearer than others—some, you might even see a completely blue sky—but regardless, you know that this is an image of our atmosphere.
But do you know just how much your atmosphere does for you?
We’ll talk about how it protects you from space rocks later on. For now, consider the energy from our own sun. The sun doesn’t just send visible light our way—it operates in all wavelengths of the electromagnetic spectrum.
Some of those wavelengths are harmful, like gamma rays, X-rays, and ultraviolet radiation. Others, like infrared radiation, microwaves, and radio waves, are perfectly fine.
The atmosphere doesn’t really pick and choose which wavelengths get through to the surface. It blocks out some radiation it doesn’t need to. At least it protects us from the harmful wavelengths.
But that’s bad news for astronomers, because those wavelengths still contain useful information about the universe.
So how to we capture and analyze them? Continue reading
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
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
Albert Einstein’s name literally sends shivers down my spine.
This is the man who discovered physics as we know it. This is the man who filled in the gaps where even Newton’s laws of motion went wrong and expanded our understanding of the universe.
This man was a genius in every right—even if his social skills were somewhat lacking.
By the way…I can’t help but notice this is my first post with actual photographs of the scientist in question, instead of portraits. We’re moving along, people…
So. To the point. Einstein is famous for taking revolutionary and widely accepted laws of physics—those that Newton figured out—and showing where there were some holes in the math. But Einstein wasn’t just an annoying critic.
He took it all a step further…and showed us how physics really works.
He came up with the idea of relativity. Continue reading
Have you ever been to the beach?
If you’re from California like me, then I’m betting you have. If you’re from a place that’s not near an ocean and you’ve never been near the water all your life, then I’ll tell you a little bit about the tides.
They happen every day, twice a day. If you find yourself a nice comfortable spot overlooking the beach, you can see the waves come into the shore and then gently roll out again. If you stay for hours on end, you’ll see the water level eventually rise a bit.
And if you stay even longer, you’ll see the water level lower back down. When it’s high, it’s called high tide, and when it’s low, it’s called low tide.
The tides are partially responsible for the myth that the moon’s gravity affects you in some kind of metaphysical way. But this isn’t true at all.
So why do the tides happen? Continue reading
So, the moon stays in orbit around the Earth, right?
Yeah, I thought so. But why? The moon’s orbit is not a straight line, which means it’s accelerated motion (using the physics definition, which is absolutely any change in speed or direction).
And in order for acceleration to happen, according to Newton’s first law of motion, a force has to happen—meaning, something has to reach out, touch the moon, and drag it into orbit around Earth.
Well, that doesn’t happen, last I checked. I mean, it’s not like we have some kind of giant cord connecting us to the moon. How crazy would that be?
So why does the moon orbit the Earth? Continue reading
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