Introduction to Astronomy: Crash Course Astronomy #1

Summary

Host Phil Plait introduces viewers to the vast expanse of astronomy, emphasizing its interdisciplinary nature involving not just astronomers but also mathematicians, engineers, and more. He discusses the scientific method's role in understanding the cosmos, the history of astronomy from ancient observations to modern telescopes, and the profound impact of technological advancements like photography and digital detectors. The script invites viewers to explore the universe's mysteries, highlighting humanity's journey from geocentrism to recognizing the Earth as a small part of an ever-expanding cosmos.

Takeaways

• 📚 Science is a body of knowledge and a method of learning, emphasizing the importance of testing hypotheses and being open to the possibility of being wrong.
• 🌌 Astronomy is the study of celestial objects and phenomena, and it's a branch of science that helps us understand our place in the universe.
• 🔭 The definition of astronomy has evolved from simply observing the sky to encompassing various scientific disciplines including chemistry, geology, and more.
• 👩‍💼 Astronomers come from diverse backgrounds, including not only those who operate telescopes but also mathematicians, engineers, technicians, programmers, and artists.
• 👨‍💻 The role of astronomers has expanded to include data analysis and interpretation, requiring knowledge in math and physics to test physical models.
• 🛠️ Engineering and technical skills are crucial for designing, building, and operating the instruments that astronomers use to gather data from space.
• 🌟 Ancient civilizations observed the sky for practical reasons, such as agriculture, which led to the development of astrology before the formalization of scientific astronomy.
• 🔮 Astrology and astronomy were once intertwined, but modern astronomy is grounded in empirical evidence and scientific method, whereas astrology is not.
• 🌍 The geocentric model, once the dominant view of the universe, has been replaced by the heliocentric model and further refined by the laws of physics and astronomical observations.
• 📹 Technological advancements, such as photography and digital detectors, have revolutionized astronomy by allowing for the capture and analysis of fainter and more distant celestial objects.
• 🚀 The use of space-based telescopes has significantly improved our observations by avoiding the distortion caused by Earth's atmosphere.

Q & A

What is the primary focus of Crash Course Astronomy as introduced by Phil Plait?

The primary focus of Crash Course Astronomy is to provide a guided tour of the Universe, covering topics such as planets, stars, black holes, galaxies, subatomic particles, and the eventual fate of the Universe.

How does Phil Plait define science in the context of astronomy?

Phil Plait defines science as a body of knowledge and a method for learning that knowledge. He emphasizes that science is about observing the Universe, forming hypotheses, and testing them, with a focus on being honest and acknowledging that our understanding may be wrong.

What unique perspective does astronomy offer according to the script?

Astronomy offers a unique perspective by putting humans in their place in the vastness of the Universe, illustrating how we are just a small part of an incredibly large and complex cosmos.

How has the definition of astronomy evolved over time?

The definition of astronomy has evolved from simply being the study of things in the sky to a more complex and interdisciplinary field. It now overlaps with other sciences like chemistry, geology, and physics, particularly when studying celestial bodies like Mars.

What roles do astronomers play beyond using telescopes?

Astronomers play a variety of roles beyond using telescopes, including programming, engineering, analyzing data, and even communicating scientific findings through teaching, writing, and media production.

How did ancient civilizations use astronomy in their daily lives?

Ancient civilizations used astronomy to track the cycles of the sky, which were important for agriculture. They noticed patterns in the stars that indicated changes in seasons, which helped them determine when to plant and harvest crops.

What is the relationship between astrology and astronomy as described in the script?

Astrology and astronomy were closely related in ancient times, with astrology being an early attempt to understand the influence of stars on human lives. However, over time, astronomy developed into a rigorous scientific discipline, while astrology is no longer considered a science.

What was the major shift in understanding the cosmos introduced by Copernicus?

The major shift introduced by Copernicus was the heliocentric model, which proposed that the Sun, not the Earth, was at the center of the solar system. This was a significant departure from the geocentric model that had been widely accepted.

How did technological advancements like the telescope and photography impact astronomy?

Technological advancements like the telescope and photography revolutionized astronomy by allowing astronomers to observe much fainter objects and capture detailed images of celestial bodies, leading to a deeper understanding of the Universe.

What are some of the key discoveries and concepts in modern astronomy?

Key discoveries in modern astronomy include the realization that stars are suns, the existence of other galaxies, the concept that we can only see a small fraction of the Universe, the creation of elements in supernovae, and the existence of dark matter and dark energy.

Outlines

00:00

🌌 Introduction to Astronomy and the Scientific Method

The script introduces the host, Phil Plait, who will guide viewers through the vastness of the Universe in the Crash Course Astronomy series. It emphasizes the scientific method, which involves observing, hypothesizing, and testing to refine our understanding of the Universe. Phil explains that science is self-correcting and that it's okay for our current knowledge to be imperfect. He also discusses the interdisciplinary nature of astronomy, which includes not just observing the sky but also understanding the underlying physics and engineering involved in space exploration. The paragraph concludes by defining astronomers as a diverse group of professionals, including those who operate telescopes, as well as programmers, engineers, and educators.

05:00

📚 The Evolution of Astronomy and Its Interdisciplinary Nature

This paragraph delves into the history of astronomy, from ancient civilizations observing celestial patterns to influence agriculture and the development of astrology. It discusses the transition from geocentrism to heliocentrism, with key figures like Copernicus, Tycho Brahe, and Johannes Kepler contributing to our understanding of the solar system. The paragraph also highlights the importance of applied math and physics in advancing astronomical knowledge, the invention of the telescope, and the subsequent technological advancements in photography and digital detectors that have revolutionized the field. It concludes by emphasizing the interdisciplinary nature of astronomy, which requires the collaboration of astronomers, engineers, software programmers, and educators.

10:05

🚀 Modern Astronomy and Its Achievements

The final paragraph of the script reflects on the significant progress made in astronomy, from the recognition that the Earth is not the center of the Universe to the exploration of other planets and the search for extraterrestrial life. It touches on the fact that our galaxy is just one among billions and that only a small fraction of the Universe is visible to us. The paragraph also discusses the role of stars in creating the elements necessary for life and the diversity of celestial bodies within our own solar system. It concludes by acknowledging the vastness of the Universe and the ongoing quest for knowledge, highlighting the contributions of various professionals in the field and the production team behind the Crash Course Astronomy series.

Keywords

💡Astronomy

Astronomy is the scientific study of celestial objects, phenomena, and the universe itself. It is a broad field that encompasses the study of planets, stars, galaxies, and the physical laws that govern these entities. In the video, astronomy is introduced as the main theme, with the host, Phil Plait, explaining that it has evolved to include various scientific disciplines beyond just observing the sky with the naked eye or telescopes.

💡Science

Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe. In the script, Phil Plait emphasizes the importance of the scientific method, which includes making observations, formulating hypotheses, and testing these through experimentation and analysis to understand the universe better.

💡Universe

The Universe refers to the entirety of space and time, and all forms of matter, energy, and events that exist within it. The video script discusses the vastness of the Universe, from our local planetary system to the far reaches of the observable cosmos, highlighting the scale at which astronomy operates.

💡Mitochondria

Mitochondria are membrane-bound organelles found in the cells of most eukaryotic organisms. They are best known for their role in generating energy through the process of cellular respiration. In the script, mitochondria are mentioned as an example of the scientific concepts that are part of our everyday existence.

💡Astrophysicist

An astrophysicist is a scientist who applies the principles of physics and chemistry to understand the nature of celestial objects and phenomena. The script mentions astrophysicists as one of the many professionals involved in the field of astronomy, who use mathematical and physical models to interpret observations from telescopes and other instruments.

💡Hubble Space Telescope

The Hubble Space Telescope is an orbiting observatory that has provided some of the most detailed images of the universe. In the script, Phil Plait shares his experience working on the Hubble Space Telescope, emphasizing the multidisciplinary nature of astronomy that includes programming and engineering.

💡Astrologer

An astrologer is someone who practices astrology, which is the belief system that the positions of celestial bodies can influence human affairs and natural phenomena. The script contrasts astrology with astronomy, highlighting the scientific basis of the latter and the lack of empirical evidence for the former.

💡Geocentrism

Geocentrism is the ancient belief that the Earth is at the center of the universe and that all celestial bodies revolve around it. The script discusses the historical shift from geocentrism to heliocentrism, reflecting the evolution of our understanding of the solar system.

💡Dark Matter

Dark matter is a hypothetical form of matter that is thought to account for approximately 85% of the matter in the universe. It does not emit or interact with electromagnetic radiation, making it invisible to the naked eye and telescopes. The script mentions dark matter as part of the unseen structures that make up our universe.

💡Dark Energy

Dark energy is a mysterious form of energy that is hypothesized to permeate all of space and accelerate the expansion of the universe. The script refers to dark energy as the driving force behind the accelerating expansion of the universe, illustrating the current frontiers of astronomical research.

💡Local Group

The Local Group is the galaxy group that includes the Milky Way, Andromeda, and other smaller galaxies. It is part of the larger cosmic structure of the universe. The script uses the Local Group as an example to explain the scale of cosmic structures and our place within them.

Highlights

Introduction to Crash Course Astronomy with host Phil Plait.

Exploration of the Universe's vastness from planets to the eventual fate of the Universe.

Science defined as a body of knowledge and a method of learning, with an emphasis on its self-correcting nature.

The importance of honesty in science to uncover the truth.

Astronomy's role in placing humanity within the broader context of the Universe.

The multidisciplinary nature of astronomy, including chemistry, geology, and engineering.

The evolution of the definition of astronomy from the study of celestial objects to a broader scientific field.

Introduction of the 'Focus On…' segment discussing the diverse roles within the field of astronomy.

Phil Plait's personal journey from a telescope operator to an astronomy communicator.

The interdisciplinary approach in analyzing data from space, involving math and physics.

The role of engineers and technicians in designing and operating astronomical instruments.

The necessity of educators, writers, and artists in communicating astronomical discoveries.

The historical development of astronomy from ancient observations to the Hubble Space Telescope.

The transition from geocentrism to heliocentrism and the contributions of Copernicus, Tycho Brahe, and Kepler.

Isaac Newton's role in advancing astronomy through the invention of calculus and his laws of motion.

The impact of the telescope and photography on the advancement of astronomical observations.

The revolution brought about by digital detectors and computer analysis in modern astronomy.

Current capabilities in astronomy, such as the search for extraterrestrial life and understanding the composition of the Universe.

The acknowledgment of the vastness of the Universe and the limitations of human knowledge.

Conclusion of the episode with a summary of the role of astronomers and the history of astronomy.

Transcripts

Hello, and welcome to Crash Course Astronomy! I’m your host, Phil Plait, and I’ll be

taking you on a guided tour of the entire Universe. You might want to pack a lunch.

Over the course of this series we’ll explore planets, stars, black holes, galaxies, subatomic

particles, and even the eventual fate of the Universe itself.

But before we step into space, let’s take a step back. I wanna talk to you about science.

There are lots of definitions of science, but I’ll say that it’s a body of knowledge,

and a method of how we learned that knowledge.

Science tells us that stuff we know may not be perfectly known; it may be partly or entirely

wrong. We need to watch the Universe, see how it behaves, make guesses about why it’s

doing what it’s doing, and then try to think of ways to support or disprove those ideas.

That last part is important. Science must be, above all else, honest if we really want

to get to the bottom of things.

Understanding that our understanding might be wrong is essential, and trying to figure

out the ways we may be mistaken is the only way that science can help us find our way

to the truth, or at least the nearest approximation to it.

Science learns. We meander a bit as we use it, but in the long run we get ever closer

to understanding reality, and that is the strength of science. And it’s all around us!

Whether you know it or not, you’re soaking in science.

You’re a primate. You have mass. Mitochondria

in your cells are generating energy. Presumably, you’re breathing oxygen.

But astronomy is different. It’s still science, of course, but astronomy puts you in your place.

Because of astronomy, I know we’re standing on a sphere of mostly molten rock and metal

13,000 kilometers across, with a fuzzy atmosphere about 100 km high, surrounded by a magnetic

field that protects us from the onslaught of subatomic particles from the Sun 150 million

km away, which is also flooding space with light that reaches across space, to illuminate

the planets, asteroids, dust, and comets, racing out past the Kuiper Belt, through the

Oort Cloud, into interstellar space, past the nearest stars, which orbit along with

gas clouds and dust lanes in a gigantic spiral galaxy we call the Milky Way that has a supermassive

black hole in its center, and is surrounded by 150 globular clusters and a halo of dark

matter and dwarf galaxies, some of which it’s eating, all of which can be seen by other

galaxies in our Local Group like Andromeda and Triangulum, and our group is on the outskirts

of the Virgo galaxy cluster, which is part of the Virgo supercluster, which is just one

of many other gigantic structures that stretch most of the way across the visible Universe,

which is 90-billion light years across and expanding every day, even faster today than

yesterday due to mysterious dark energy, and even all that might be part of an infinitely

larger multiverse that extends forever both in time and space.

See? Astronomy puts you in your place.

But what exactly is astronomy? This isn’t necessarily an obvious thing to ask. When

I was a kid, it was easy: Astronomy is the study of things in the sky. The sun, moon,

stars, galaxies, and stuff like that. But it’s not so easy to pigeonhole these days.

Take, for example, Mars. When I haul my ‘scope out to the end of my driveway and look at

Mars, that’s astronomy, right? Of course! But what about the rovers there? Those machines

aren’t doing astronomy, surely. They’re doing chemistry, geology, hydrology, petrology…

everything but astronomy!

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

it’s branched out quite a bit from there. Borders between it and other fields of science

are fuzzy… a theme I’ll be hitting on several times over this series. Humans might

like firm, delineated boundaries between things, but nature isn’t so picky.

And that brings us to our first edition of “Focus On…”

This week’s topic: Astronomers! Who are we? What do we do?

I used to look through telescopes for a living, or at least study the data that came from

detectors strapped onto them. But now I talk and write (and make videos) about astronomy,

and relegate my viewing to my personal backyard telescope. But I still consider myself an

astronomer, so that should give you an idea that there’s a lot of wiggle room in the profession.

In fact, when I worked on Hubble Space Telescope, I was actually hired as... a programmer!

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

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

Once the data from that camera are taken and analyzed, you have to know what to do with

them. Do the observations fit the physical model of how stars blow up, or how galaxies

form, or the way gas flows through space? Well, you better know your math and physics,

because that’s how we test our hypotheses. And someone who does that is generally called

an astrophysicist.

Of course, those telescopes and detectors don’t create themselves. We need engineers

to design and build them and technicians to use them.

Most astronomers don’t actually use the telescopes themselves anymore; someone who’s

trained in their specific use does that for them.

Some of those instruments go into space, and some go to other worlds, like the moon and Mars.

We need astronomers and engineers and software programmers who can build those, too.

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

professors, writers, video makers, even artists.

So I’ll tell you what: If you have an interest in the Universe, if you love to look up at

the stars, if you crave to understand what’s going on literally over your head, then who

am I to say you’re not an astronomer?

However you define astronomy, humans have been looking up at the sky for as long as

we’ve been humans. Certainly ancient people noticed the big glowy

ball in the sky, and how it lit everything up while it was up, and how it got dark when

it was gone. The other, fainter glowy thing tried, but wasn’t quite as good as lighting

up the night. They probably took that sort of thing pretty seriously. They probably also

noticed that when certain stars appeared in the sky, the weather started getting warmer

and the days longer, and when other stars were seen, the weather would get colder and

daytime shorten.

And when humans settled down, discovered agriculture, and started farming, noticing those patterns

in the sky would have had an even greater impact. It told them when to plant seeds,

and when to harvest.

The cycles in the sky became pretty important. So important that it wasn’t hard to imagine

gods up there, looking down on us weak and ridiculous humans, interfering with our lives.

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

length of the day, they control our lives too… and astrology was born.

Astrology literally means “study of the stars”; as a word it’s been used before

science became a formal method of studying nature. It irks me a bit, since it got the

good name, and now we’re stuck with “astronomy,” which means “law or culture of the stars."

That’s not really what we do! But what the heck. Words change meaning over time, and

now it’s pretty well understood that astronomy is science, and astrology… isn’t.

Millennia ago, astrology was as close to science as you got. It had some of the flavors of

science: astrologers observed the skies, made predictions about how it would affect people,

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

The thing is, it really didn’t; the fault of astrology lies in ourselves and not our

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

which is why they sometimes sit in casinos pumping nickels into machines that are in

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

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

led to a more rigorous understanding of how things worked in the heavenly vault.

It wasn’t overnight, of course. This took centuries. Before the invention of the telescope,

keen observers built all sorts of odd and wonderful devices to measure the heavens,

and in fact it was before the telescope was first turned to the sky that a huge revolution

in astronomy took place.

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

the skies turn above us. The sun rises, the sun sets. The moon rises and sets, the stars

themselves wheel around the sky at night. Clearly, the Earth is motionless, and the

sky is what is actually moving. In fact, if you think about it, geocentrism

makes perfect sense that all the objects in the sky revolve about the Earth, and are fixed

to a series of nested spheres, some of which are transparent, maybe made of crystal, which

spin once per day. The stars may just be holes in the otherwise opaque sphere, letting sunlight though.

Sounds silly to you, doesn’t it?

Well, here’s the thing: If you don’t have today’s modern understanding of how the

cosmos works, this whole multiple-shells-of-things-in- the-sky thing actually does make sense. It explains

a lot of what’s going on over your head, and if it was good enough for Plato, Aristotle,

and Ptolemy, then by god it was good enough for you. And speaking of which, it was endorsed

by the major religions of the time, so maybe it’s better if you just nod and agree and

don’t think about it too hard.

But a few centuries ago things changed. Although he wasn’t the first, the Polish mathematician

and astronomer Copernicus came up with the idea that the sun was the center of the solar

system, not the Earth. His ideas had problems, which we’ll get to in a later episode, but

it did an incrementally better job than geocentrism.

And then along came Tycho Brahe and Johannes Kepler, who modified that system, making it

even better. Then Isaac Newton - oh, Newton - he invented calculus partly to help him

understand the way objects moved in space. Over time, our math got better, our physics

got better, and our understanding grew. Applied math was a revolution in astronomy, and then

the use of telescopes was another. Galileo didn’t invent the telescope, by

the way, but made them better; Newton invented a new kind that was even better than that,

and we’ve run with the idea from there.

Then, about a century or so ago, came another revolution: photography. We could capture

much fainter objects on glass plates sprayed with light-sensitive chemicals, which revealed

stars otherwise invisible to us, details in galaxies, beautiful clouds of gas and dust in space.

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

even more sensitive than film. We could use computers to directly analyze observations,

and our knowledge leaped again. When these were coupled with telescopes sent in orbit

around the Earth - where our roiling and boiling atmosphere doesn’t blur out observations

- we began yet another revolution.

And where are we now?

We’ve come such a long way! What questions can we routinely ask that our ancestors would

not have dared, what statements made with a pretty good degree of certainty?

Think on this: The lights in the sky are stars! There are other worlds. We take the idea of

looking for life on alien planets seriously, and spend billions of dollars doing it. Our

galaxy is one of a hundred billion others. We can only directly see 4% of the Universe.

Stars explode, and when they do they create the stuff of life: the iron in our blood,

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

kind of star in the Universe is so faint you can’t see it without a telescope. Our solar

system is filled to overflowing with worlds more bizarre than we could have dreamed.

Nature has more imagination than we do. It comes up with some nutty stuff. We’re clever

too, we big-brained apes. We’ve learned a lot… but there’s still a long way to go.

So, with that, I think we’re ready. Let’s explore the universe.

Today you learned what astronomy is, and that astronomers aren’t just people who operate

telescopes, but include mathematicians, engineers, technicians, programmers, and even artists.

We also wrapped up with a quick history of the origins and development of astronomy,

from ancient observers to the Hubble Space Telescope.

Crash Course is produced in association with PBS Digital Studios.

This episode was written by me, Phil Plait. The script was edited by Blake de Pastino,

and our consultant is Dr. Michelle Thaller. It was co-directed by Nicholas Jenkins and

Michael Aranda, and the graphics team is Thought Café.