Ancient cultures used mythology and everyday objects to name constellations, and modern astronomy recognizes 88 constellations. Some constellations are only visible part of the year as the Earth revolves around the Sun, but circumpolar constellations in the northern sky appear to circle around Polaris and can be seen all year. Astronomers measure stars' absolute and apparent magnitudes, parallax, distance in light-years, and determine temperature based on color, with hotter stars appearing blue-white and cooler stars orange or red.

1. Chapter 25 Section 1: STARS

2. Patterns of stars: Constellations Ancient cultures used mythology or everyday items to name constellations.

3. Modern Astronomy Studies 88 Constellations

4. Some constellations are not visible all year because Earth revolves around the Sun.

5. Circumpolar constellations in the northern sky appear to circle around Polaris and are visible all year.

6. Circumpolar Constellations

7. Star Magnitude Absolute magnitude: measure of the amount of light a star actually gives off. Apparent magnitude: measure of the amount of a star’s light received on Earth

8. Space Measurement Astronomers measure a star’s parallax The shift in its position when viewed from 2 different angles.

9. Distance is measured in light-years Light year: distance light travels in a year.

10. Star Properties Color indicates temperature Hot stars are blue-white

11. Cool stars look orange or red