How Were Atoms Discovered?

Welcome to my fourth “Science Answers” post! If you have a question, you can ask it in the comments here, or ask it in an email. Or find me on Facebook!

Q: (1) How did scientists find elements in the first place? Could there be more undiscovered elements?
(2) How did scientists create the periodic table?
(3) How do we know that everything is made up of atoms, when atoms are so small that they can’t even reflect light (a necessity for seeing them)?
(asked by Mukesh Garbyal)

Really good questions! I was asked these in a comment on my post “Types of Atoms,” and chose to answer them in a post of their own.

Let’s take this apart. I actually want to address the third part of the question first, since it contains a misconception: atoms can reflect light. Their interaction with light is actually why we can see anything in the world.

How?

Continue reading

Helium Ignition in Stars

When I first began learning about stars, I expected them to be violent and chaotic places. And to an extent, they certainly are.

Pressures are unbelievably high in their cores—high enough to smash protons together, and this is no small feat. And near their surfaces, magnetic field loops twist and tangle and a number of eruptions disrupt satellite function on Earth from time to time.

Beyond the obvious, though, stars are actually surprisingly…peaceful.

While stable, they only produce enough energy to sustain their own mass. Their way of maintaining homeostasis is beautiful in its simplicity.

But this can’t last forever. Eventually, stars exhaust their hydrogen fuel. Their cores begin to contract and their outer envelope expands to enormous proportions.

What’s next for a star—and why?

Continue reading

What Happens in an Expanding Star’s Core?

Depending on their mass, stars can remain stable for millions and even billions of years. The most massive stars live for “only” about 10 million years, but models predict that the least massive live for much longer—longer than cosmologists believe the universe has existed.

As long as stars are stable, they exist on the “main sequence.” That’s just a fancy word for the best balance between temperature and mass. For a while now, we’ve been exploring the main sequence in depth, and I’ve shown you how stars eventually lose stability and “leave” the main sequence.

As stars exhaust their fuel, their internal structures change drastically. Their cores contract, but their outer layers are forced to expand, and they become giants. You’d think the next thing we’d cover would be what happens to these giant stars, right?

Well…not quite! At this point, something downright weird is going on in their cores, and it’s well worth a closer look…

Continue reading

How a Star Expands

Well, everyone, look who’s back!

For those of you who are not signed up for my newsletter, I’m sorry I’ve been away forever—life happened. It’s been a very rough three months. I hope you’re all doing well in light of the COVID-19 pandemic. I know it’s pretty tough right now, but we’ll pull through. Hang in there! 🙂

And now, for some long-awaited astronomy…

Meet Betelgeuse, a bright star in the winter constellation Orion.

Betelgeuse is a cool red supergiant that we’ll talk about a lot more in just a couple weeks, when we cover variable stars. Not too long ago, it was the height of excitement among astronomers. No one was sure why it…well…appeared to be dimming.

Yeah. Like a lightbulb. It was literally getting fainter—considerably fainter.

It’s pretty normal for Betelgeuse, like any other variable star, to fluctuate in brightness over time, but it was doing something downright weird. We’ll explore what was going on with it soon enough.

For now, let’s take a look at why Betelgeuse, as a supergiant, is so darn big.

Continue reading

The Adult Life of a Star

Stars are like cars. They need fuel to go. And also like cars, they don’t have an infinite supply.

But here’s where the metaphor breaks down. They can never refuel.

Yup. That’s right. For their entire lives, stars are stuck with only the amount of fuel they formed with. They can’t get more.

What happens when you’re driving, and you run out of gas?

Well, if you can’t refuel, you’re gonna have to call a tow truck. But stars don’t have tow trucks, and for them, it’s not a matter of moving or not—it’s a matter of life and death, such as it is.

But how does that work?

Continue reading

Stars: The Limits of “Normal”

How big—or small—can a star get?

As with most questions in astronomy, the answer to that is not definitive. But stellar models can give us a pretty good idea.

Mathematical models of stars tell us that their life—or, to use a less personifying term, function—depends on the balance between two opposing forces: internal pressure and gravity.

Stars produce energy to function. They don’t just do this to light up our skies and provide for life on their orbiting worlds. They need to produce energy to constantly support the weight of their own mass.

The more massive stars are, the more energy they need to produce—and the reverse is true too. There has to be a balance.

But is there a limit? Is there a point where balance is impossible?

Continue reading

What is a “Normal” Star?

If we were talking about people, I’d say there’s no such thing as a “normal” person. We’re all weird in our own way—that’s what makes us unique and ourselves.

However, there’s such a thing as a functional human—a human with a combination of functional organ systems and/or prosthetics that makes daily life navigable. And just as no star is exactly alike, there are functional stars.

Nature makes mistakes all the time. It is not intelligent—it doesn’t know the best way to do anything. It doesn’t know the path of least resistance or least effort. It just tries everything at random, and we get to observe what happens.

A “normal” star is what happens when nature stumbles upon the right conditions. But…what does that mean?

Continue reading

What Goes On Inside a Star?

Our sun is undoubtedly the star we know the best. It’s only 93 million miles away—which might seem far, but isn’t that large a distance when you realize that the nearest neighboring star is a whole 4.3 light-years away.

As in, it takes light—yeah, that same stuff that hits the ground from your flashlight in a split second—a whole 4.3 years to get here.

We’re pretty familiar with our star’s interior. We know it produces most of its energy in its core, a relatively small but very hot region at its center. We also know that energy then radiates outward until it hits the convective layer.

There, the energy gets stuck in circulation for a bit until it finally manages to leave the sun’s surface.

But…how normal is that? Is it the same for all stars, or just the sun?

Continue reading

What Keeps a Star Stable?

animal_star.jpg

All life as we know it has to maintain homeostasis—that is, keep internal goings-on regulated. Body temperature is just one example. Mammals can maintain a stable body temperature with no trouble. Reptiles have to bask in the sun to keep warm.

You’re probably familiar with this idea. When you sweat, your body is trying to cool down. When you shiver, it’s trying to warm up. These are all examples of your own body maintaining its own homeostasis.

And then there’s blood pressure, heart rate, hormones, and pH—not that I have any real idea how all that works, but I know they’re all things that your body regulates on its own. Homeostasis is an important thing. Basically, when it fails, things go wrong.

And stars do the same thing. Continue reading