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Hello and welcome to Crash course. Astronomy.

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I'm your host Phil Plate and I'll be taking

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you on a guided tour of the entire universe.

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You might want to pack a lunch

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over the course of this series.

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We'll explore planets, stars, black holes, Galaxies,

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subatomic particles and even the eventual fate of the universe itself.

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But before we step into space, let's take a step back.

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I want to talk to you about science.

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There are lots of definitions of science,

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but I'll say that it's a body of knowledge and a method of how we learn that knowledge.

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Science tells us that stuff we think we know may not be perfectly known.

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It may be partly or entirely wrong.

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We need to watch the universe see how it behaves,

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make guesses about why it's doing what it's doing.

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And then try to think of ways to support or disprove those ideas.

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That last part is important.

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Science must be above all else honest,

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if we really want to get to the bottom of things,

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understanding that our understanding might be wrong is essential

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and trying to figure out the ways we may be mistaken is the only way that science

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can help us find our way to the truth or at least the nearest approximation to it.

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Science learns we meander a bit as we use it.

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But in the long run,

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we get closer and closer to understanding reality and that

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is the strength of science and it's all around us.

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Whether you know it or not, you're soaking in science, you're a primate.

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You have mass mitochondria in your cells are generating energy,

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presumably you're breathing oxygen.

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But astronomy is different. It's still science, of course.

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But astronomy puts you in your place because of astronomy.

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I know we're standing on a sphere of mostly molten rock

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and metal 13,000 kilometers across with a fuzzy atmosphere about 100 kilometers

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high surrounded by a magnetic field that protects us from the

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onslaught of subatomic particles from the sun 150 million kilometers away,

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which is also flooding space with light that

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reaches across space to illuminate the planets,

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asteroids, dust and comets

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racing out past the kuiper belt through the

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or cloud into interstellar space past the nearest

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stars which orbit along with gas clouds and dust lanes in a gigantic spiral galaxy.

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We call the milky way that has a supermassive black hole in its center and

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is surrounded by 150 globular clusters and a halo of dark matter and dwarf Galaxies,

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some of which it's eating all of which can be seen

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by other Galaxies in our local group like Andromeda and Triangulum.

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And our group is on the outskirts of the Virgo galaxy cluster,

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which is part of the Virgo supercluster,

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which is just one of many other gigantic structures that

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stretch most of the way across the visible universe,

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which is 90 billion light years across and

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expanding every day even faster today than yesterday due

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to mysterious dark energy and even all that might

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be part of an infinitely larger multiverse that extends

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for

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both in time and space. See, astronomy puts you in your place.

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But what exactly is astronomy?

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This isn't necessarily an obvious thing to ask when I was a kid. It was easy.

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Astronomy is the study of things in the sky, the sun, moon, stars,

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Galaxies and stuff like that.

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But it's not so easy to pigeon hole these days. Take for example, Mars,

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when I haul my scope out to the end of my driveway and look at Mars.

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That's astronomy, right?

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Of course. But what about the rovers there? Those machines aren't doing astronomy.

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Surely they're doing chemistry, geology, hydrology, petrology, everything.

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But astronomy.

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So nowadays, what's astronomy, I'd say it's still studying stuff in the sky,

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but it's branched out quite a bit from there.

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Borders between it and other fields of science are

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a theme I'll be hitting on several times over this series.

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Humans might like firm delineated boundaries between things but nature isn't so

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picky and that brings us to our first edition of Focus on

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this week's topic, astronomers. Who are we? What do we do?

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I used to look through telescopes for a living or at

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least study the data that came from detectors strapped onto them.

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But now I talk and write and make videos about

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astronomy and relegate my viewing to my personal backyard telescope.

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But I still consider myself an astronomer.

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So that should give you an idea that there's a lot of wiggle room in the profession.

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In fact, when I worked on Hubble space telescope,

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I was actually hired as a programmer,

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I coded in the language used by the folks helping to build and calibrate a camera

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that was due to launch into space and be installed on Hubble by an astronaut.

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Once the data from that camera are taken and analyzed,

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you have to know what to do with them.

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Do the observations fit the physical model of how stars blow up

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or how Galaxies form or the way gas flows through space.

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Well,

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you better know your math and physics because that's how we test our hypotheses.

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And someone who does that is generally called an astrophysicist.

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Of course, those telescopes and detectors don't create themselves.

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We need engineers to design and build them and technicians to use them.

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Most astronomers don't actually use the telescopes themselves anymore.

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Someone who's trained in their specific use, does that for them,

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some of those instruments go into space and some go to other worlds like the moon

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and Mars,

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we need astronomers and engineers and software

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programmers who can build those too.

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And then at the end of all this, we need people to tell you all about it, teachers,

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professors, writers, video makers, even artists.

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So I'll tell you what if you have an interest in the universe.

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If you love to look up at the stars, if you crave to understand what's going on,

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literally over your head,

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then who am I to say you're not an astronomer, however you define astronomy,

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humans have been looking up at the sky for as long as we've been human.

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Certainly ancient.

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People noticed the big glowy ball in the sky and how it lit everything

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up while it was up and how it got dark when it was gone.

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The other fainter glowy thing tried but wasn't

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quite as good at lighting up the night.

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They probably took that sort of thing pretty seriously.

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They probably also noticed that when certain stars appeared in the sky,

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the weather started getting warmer and the days

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longer and when other stars were seen,

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the weather would get colder and daytime short.

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And when humans settled down, discovered agriculture and started farming,

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noticing those patterns in the sky would have had an even greater impact.

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It told them when to plant seeds and when to

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harvest the cycles in the sky became pretty important,

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so important that it wasn't hard to imagine gods up there looking

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down on us weak and ridiculous humans interfering with our lives.

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Surely if the stars tell us when to plant and control the weather,

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seasons and the length of the day

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they control our lives too. And astrology was born.

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Astrology literally means study of the stars as a word.

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It's been used before science became a formal method of studying nature.

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It irks me a bit since it got the good name.

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And now we're stuck with astronomy, which means law or culture of the stars.

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And that's not really what we do,

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but what the heck words change meaning over time.

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And now it's pretty well understood that astronomy is science and astrology

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isn't millennia ago. Astrology was as close to science as you got,

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it had some of the flavors of science.

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Astrologers observed the skies made predictions about how it would affect people.

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And then those people would provide evidence for it by swearing up and down.

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It worked.

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The thing is it really didn't,

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the fault of astrology lies in ourselves and not our stars.

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People tend to remember the hits and forget the misses when predictions are made,

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which is why they sometimes sit in

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casinos pumping nickels into machines that are proven

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to be nothing more than a method for reducing the number of nickels you have.

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But astrology led people to really study the sky and find the patterns there,

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which led to a more rigorous understanding of how things

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really worked in the heavenly vault it wasn't overnight.

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Of course, this took centuries

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before the invention of the telescope, keen observers,

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built all sorts of odd and wonderful devices to measure the heavens.

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And in fact,

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it was before the telescope was first turned to the

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sky that a huge revolution in astronomy took place.

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It is patently obvious that the ground you stand on is fixed rooted if you will.

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And the skies turn above us, the sun rises, the sun sets,

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the moon rises and sets the stars themselves wheel around the

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at night.

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Clearly, the earth is motionless and the sky is what is actually moving.

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In fact, if you think about it,

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geo centrism makes perfect sense that all the objects in the sky revolve

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about the earth and are fixed to a series of nested spheres.

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Some of which are transparent may be made of crystal which spin once per day,

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the stars may just be holes in otherwise opaque spheres letting sunlight through.

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Sounds silly to you, doesn't it?

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Well, here's the thing,

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if you don't have today's modern understanding of how the cosmos works.

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This whole multiple shells of things in the sky thing actually does make sense.

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It explains a lot of what's going on over your head.

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And if it was good enough for Plato Aristotle and Ptolemy

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by God, it was good enough for you.

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And speaking of which it was endorsed by the major religions of the time,

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so maybe it's better if you just nod and agree and don't think about it too hard.

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But a few centuries ago, things changed.

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Although he wasn't the first,

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the Polish mathematician and astronomer Copernicus came up with the idea

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that the sun was the center of the solar system,

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not the earth.

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His idea had problems which we'll get to in a later episode,

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but it did an incrementally better job than geo centrism.

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And then along came Tico Brahe

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and Johannes Kepler, who modified that system making it even better. Then

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Isaac Newton,

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Newton,

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he invented calculus partly to help him understand

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the way objects moved in space over time.

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Our math got better.

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Our physics got better and our understanding grew

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applied math was a revolution in astronomy.

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And then the use of telescopes was another Galileo didn't

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invent the telescope by the way but made them better.

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Newton invented a new kind that was even better than that.

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And we've run with the idea from there then

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about a century ago came another revolution photography.

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We could capture much fainter objects on glass plates sprayed with light

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sensitive chemicals which revealed stars otherwise

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invisible to us details in Galaxies,

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beautiful clouds of gas and dust in space.

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And then in the latter half of the last century, digital detectors were invented,

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which were even more sensitive than film.

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We could use computers to directly analyze observations.

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And our knowledge leaped again

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when these were coupled with telescopes sent into orbit around the

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earth where our roiling and boiling atmosphere doesn't blur out observations.

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We began yet another revolution and where are we? Now? We've come such a long way.

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What questions can we routinely ask that our ancestors would not have dared?

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What statements made with a pretty good degree of certainty?

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Think on this, the lights in the sky are stars.

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There are other worlds.

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We take the idea of looking for life on alien

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planet seriously and spend billions of dollars doing it.

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Our galaxy is one of 100 billion others.

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We can only directly see 4% of the universe stars explode.

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And when they do, they create the stuff of life, the iron in our blood,

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the calcium in our bones, the phosphorus that is the backbone of our DNA.

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The most common kind of star in the universe is so faint.

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You can't even see it without a telescope.

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Our solar system is filled to overflowing with

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worlds more bizarre than we could have dreamed.

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Nature has more imagination than we do. It comes up with some nutty stuff.

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We're clever too. We big brain apes, we've learned a lot,

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but there's still a long way to go. So with that, I think we're ready.

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Let's explore the universe today.

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You learned what astronomy is and that astronomers aren't just people who operate

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telescopes but include mathematicians, engineers, technicians, programmers,

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and even artists.

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We also wrapped up with a quick history

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of the origins and development of astronomy from ancient

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observers to the Hubble space telescope crash course

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is produced in association with PBS digital studios.

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This episode was written by me Phil Plate.

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The script was edited by Blake

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Destino and our consultant is Dr

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Michelle Fowler.

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It was co directed by Nicholas Jenkins and Michael

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Aranda. And the graphics team is Thought Cafe.