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Welcome to Astronomy

What is Astronomy?

Astronomy is a natural science that aims to understand, explain, and predict observations of the Universe. The Universe is all of space and time and everything in it.

Astronomy focuses on the study of celestial objects: those outside the atmosphere of the Earth. The objects we'll learn about include the sun, moon, stars, and planets that you can see in our sky.

To understand how Astronomy works, we need to learn about the full Universe. The Universe also includes: gas, dust, comets, asteroids, galaxies, black holes, aliens (maybe), you, your friends and family, every human that will ever live, supernovae explosions, gamma-ray bursts, all matter, and all forms of energy.

This Introduction to Astronomy course is devoted to giving all of you an understanding of the Universe and our place in it. 

Questions in Astronomy

In this course, we will talk about some big questions that people have about the Universe. Some are answered (✔️), some are in progress (🛠️).

  • Why do we have days, seasons, months, and years? ✔️
  • What lights the sky? ✔️
  • How does the universe work? 🛠️
  • How did we get here? 🛠️
  • Are we alone? 🛠️

We also want you to understand how we know: how we as humans learned (or how we are learning) the answers to each of these question.

Course trailer

[Course trailer video]

Astronomy is the oldest science. We have records of star observations from more than a thousand years ago. Early architecture aligns with astronomical phenomena, like the equinoxes.

In modern cities, ambient light obscures most stars. Away from cities, the band of our galaxy glows across the sky. All the stars we see at night are in our Milky Way Galaxy.

Seen through a telescope, a bright spot in the night sky might turn out to be thousands of stars clustered within our Milky Way. In some bright patches of sky, we find other galaxies, each the size of our Milky Way, each made of billions of distant stars.

Observing the sky has let humans explain and predict the dance of the Earth, Moon, and Sun. We learn about comets and planets, what powers the sun, and how stars are born. We learn how planets form - both large and small, around our Sun and other stars. We see how stars explode, how black holes warp space, and how space itself ripples when black holes collide.