I omit here the supporting evidence for these points of current understanding. I present them as an invitation to further study and a framework for understanding observations.

1. The universe has a history.
   • It was very hot and dense at the ``big bang'' about 10 to 15 billion years ago.
2. The laws of physics apply throughout the universe as on earth.
3. Most of the matter that we see is in galaxies. Here is a view from the Hubble Space Telescope.
4. The matter that we see in galaxies is in gas, dust, and stars. Here is a Hubble Space Telescope picture of gas and dust with new stars forming inside the dust.
5. Most of the matter in the universe is some kind of matter that we can't see (called ``dark matter.'')
6. We live in a galaxy that looks something like this called the Milky Way.
   • Given that the galaxy is pancake shaped, what should this look like in the sky?
7. The sun is a star.
8. There are nine planets that go around the sun. (The ``solar system.'')
   1. Mercury
   2. Venus
   3. Earth with its moon.
   4. Mars
   5. Jupiter
   6. Saturn
   7. Uranus
   8. Neptune
   9. Pluto with its moon Charon.
9. Most of the planets have moons that move around the planets. Here is Io, one of the moons of Jupiter.

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