Hi. It's Paul Andersen and this disciplinary core idea ESS1A. It's on the
universe and its stars. NASA pointed its Hubble space telescope at the darkest part of the
sky. And they took a long image. And what they found is something like this. And what
you're looking at right here, again the darkest part of the sky, are thousands of galaxies
that are literally billions of light years away. And so the universe is immense. Wherever
we look, we find galaxies. And those are filled with billions of stars. And so again the universe
is everything that we can see. It's filled up with galaxies. We live in one called the
Milky Way galaxy. I can't show you a picture of it because you're inside of it. But sometimes
on a dark night you can see this really really light place in the sky. And that's going to
be kind of looking into the Milky Way galaxy. Within that we have billions of stars. And
each of those have their own little solar system as they revolve around that star. And
then we're just one planet around the sun. And so that's kind of where you are in the
universe. But what is the universe? The universe is really really old. It's about 13.7 billion
years old. It was formed, our current theory, it was formed through a big bang. There was
this massive explosion where even the matter of the universe was formed in the first few
minutes. And it's been racing away ever since. What kind of evidence do we have for that?
Well no matter where we look in the universe we find that everything is moving away from
us. And so if we play the clock backwards then everything was closer and closer. And
eventually at one point was at what scientists call a singularity. What is some other evidence?
Well we get this background radiation. And we're getting microwaves. And that's from
the big bang. And when you're watching a television channel and you see that static, a portion
of that is actually background radiation from the big bang. But what is the universe made
up of? It's primarily made up of hydrogen and helium. So when you're looking at the
stars you're mostly looking at hydrogen and helium. Where did the rest of us come from?
Well everything that is iron and lighter on the periodic table came from the nuclear fusion
inside stars. And what about the rest of the periodic table? That came from supernova or
explosions of stars. And so you literally are made of star dust, which is pretty cool.
How do we know so much about the universe? Well we use telescopes to figure out how the
universe works. And those telescopes are looking at visible light, like an optical telescope.
And then we're also looking at invisible light. We're looking at radio waves and x-rays and
micro waves coming to us from space. And we start to figure out some patterns. And so
if we look at each of those stars. And we look at the spectra, in other words the light
coming from it, the luminosity, how bright it is, we start to figure out these patterns.
And we start to figure out evolution of stars. Because stars go through evolution. They go
through a specific life span. And so our sun is a typical star. And it was born and will
live about 10 billion years. Don't be scared. We're about half of the way there. And so
we're about half of the way through this 10 billion year life span. And our sun will eventually
get massive. It will envelope the earth and it will eventually, as it loses its energy
or its fuel it will form something called a white dwarf. And it will give off no luminosity
anymore. And so how do we teach all of this in school? Well in the lower elementary grades
we want to start talking about the things that students can see in the sky. That is
the sun, the moon and the stars. And we want to start figuring out patterns about their
motions during the day, during the month and during the year. And so it's really easy to
do this. You can observe the sun during different times of the day and the moon during different
times of the day. We can describe that and over time we can eventually make predictions.
When can we see the sun? Can we see it at night? No. When can we see the moon? Can we
see it at night? Yeah. Can we see it during the day? Yeah. And what does it look like?
And what about the stars? And what stars can we see during different seasons? And so you
want students making observations on their own. We can always use telescopes to give
us better data about that. And the internet allows you to see images and even control
some telescopes. As we move into the upper elementary grades, we want to push this point
home that the sun is simply a star. It's a star that's very close to us. And so it's
really really big. And has a huge amount of energy. But it's one of billions and billions
of stars in our own galaxy that we can see. And again we can even see galaxies outside
of that. Some of them are really, really big. Some are relatively small compared to the
sun. But their distances are going to vary how far they are away from us, even though
the look flat. It's three dimensional. As we move into middle school we want to start
reevaluating this observation, describing and making prediction. In other words we want
to understand why the sun moves in the way it does. And why does the moon move in the
way it does? What do we want to add to that? We want to add models. Our current model,
our heliocentric model, this idea that the sun is at the center and the earth orbits
around that and the moon orbits around us. And so we can use those models to better understand
what we're actually observing. As we move into high school we want to start talking
about stellar evolution. This idea that stars will go through a specific lifespan. And that
our sun is going to last about 10 billion years overall and we're about half way there.
We want to talk about our place in the galaxy. So we're inside the Milky Way galaxy. This
is just an artist's depiction of this. But it's massive. It has somewhere between 104
billion stars inside of that. And we get variation in that because it depends on what you count
as a star and what we can see as a star. But then our galaxies are inside what's called
the observable universe. And so we're going to have billions of galaxies found within
that universe. And then you want to start to emphasize this idea that we can look at
stars and patterns start to emerge. And that we can see more in space then you can see
with a naked eye through telescopes. So that's the universe. It's really massive. It has
billions of galaxies. Inside that billions of stars. And you're just on one planet and
orbit around one of those, the sun. And I hope that was helpful.