1. Our Universe

2. The universe is everything that exists including all matter and energy The universe is 13.7 billion years old. No one knows if the universe is infinitely large. Astronomers have indirect evidence that the universe extends beyond what we can see.

3. Distances in the universe Astronomers use the term light-year to describe distances in the universe. Light travels 300 000 km/s and can go 9.46 x 10 12 km in one year – this is known as 1 light-year.

4. Stuff we find in the universe Our solar system: consists of our Sun and all of the objects that travel around it (planets, moons, asteroids)

5. Stuff we find in the universe Galaxies: we are part of the Milky Way galaxy. A galaxy is a huge collection of gas, dust, and hundreds of billions of stars and planets. Milky Way Galaxy Andromeda Galaxy – 2.5 million light years away

6. Stuff we find in the universe Dark Matter: Matter in the space between galaxies that is invisible. Studies are going on now to discover the nature of this matter.

7. Stuff we find in the universe Black Holes: A region in space where the force of gravity is so huge that nothing can escape, including light.

8. Places humans have been in our universe:

9. Expanding Universe The universe is expanding: galaxies are moving away from one another. How do astronomers know this? –Galaxies emit light in a recognizable pattern. When they are moving, the pattern shifts. HERE’S WHY: –Light travels as a wave. –Each colour of light has a wavelength.

10. Expanding Universe When light waves move, the wavelength gets squished on one side and stretched out on the other. –E.g. Duck on a pond

11. Expanding Universe Diagram A shows a light spectrum for a stationary galaxy. Diagram B shows a light spectrum for a galaxy that is moving away from us. The wavelengths of the lines have moved toward the red end of the spectrum. “RED SHIFT” A B

12. Origins of the Universe If galaxies are moving apart, then they must have started out closer together. Big Bang Theory: accepted theory for how the universe began.

13. Big Bang 13.7 billion years ago, an explosion started the expansion of the universe. Particles rushed away from one another. The universe became very hot. As expansion and cooling occurred, common particles (helium and hydrogen) began to form.

14. Evidence for the Big Bang Edwin Hubble discovered that the universe is expanding. Cosmic Microwave Background Radiation (CMB) –as the universe expanded, the wavelength of radiation stretched from gamma rays (at the Big Bang) to microwaves (now)

15. Who discovered CMB? In 1965, Arno Penzias and Robert Wilson were attempting to measure microwaves from space. –They discovered radiation coming from all directions in space: remains of the energy that exploded outward with the Big Bang NASA’s COBE satellite discovered cosmic microwaves emanating from outer space.

16. Video video