Ch. 15-1 Stars Chapter 19, Section 1 Part 3

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

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

Motions of Stars Because of the 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.

Motion of Stars (con’t) Because of the earth’s rotation, the stars all seem to circle Polaris (the north star) once every 24 hours.

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

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