Here are are some key parts of modern astronomers' understanding
of the universe.
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.
- The universe has a history.
- It was very hot and dense at the ``big bang'' about 10 to 15
billion years ago.
- The laws of physics apply throughout the universe as on earth.
- Most of the matter that we see is in galaxies. Here is a
view from the Hubble Space
- The matter that we see in galaxies is in gas, dust, and stars.
Here is a Hubble Space Telescope
of gas and dust with new stars forming inside the dust.
- Most of the matter in the universe is some kind of matter that
we can't see (called ``dark matter.'')
- 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?
- The sun is a star.
- There are nine planets that go around the sun. (The ``solar system.'')
- Earth with its moon.
- Pluto with its moon Charon.
- Most of the planets have
that move around the planets. Here is Io, one of the moons of Jupiter.
ASTR 121 Home
Davison E. Soper, Institute of Theoretical Science,
University of Oregon, Eugene OR 97403 USA