1. 15-1 (part 3) | Stars

2. Distance to the Stars
A light-year is the distance light will travel in one year
The nearest star to the sun is 4.3 light- years away
Some stars are billions of light-years away
6,000,000,000,000
miles!

3. Parallax Stars near the Earth appear to move more than distant stars
This apparent shift in position is called parallax

5. How does parallax affect how we see objects in outer space?

6. Motion of Stars
Because of Earth’s tilt and revolution around the sun, we see different parts of the sky at night. We see different constellations at different times of the year

7. Motion of Stars (Con’t)
Because of Earth’s rotation, the stars seem to circle Polaris (the North Star) once every 24 hours

8. Motion of Stars (Con’t)
Even though the stars are moving in space, they are so far away the constellations that look the same to us now as they did to the Greeks who named them thousands of years ago

9. Review Is a yellow star hotter or cooler than an orange star?
Supposed you see two stars of the same magnitude. If one star is actually four times as far away as the other, how much brighter would the farther actually be?