1. Astronomy Earth Science, Chapter 4 5th Grade Nazareth Intermediate School

2. What is known about stars? I.The Sun A.At the center of our universe 1.Average brightness, looks the brightest to us because it is closer to the Earth than any other star B.Hot ball of glowing gases

3. What is known about stars? What is the sun made of? The sun is a huge, glowing sphere of hot gas. Most of this gas is hydrogen (about 70%) and helium (about 28%). Carbon, nitrogen and oxygen make up 1.5% and the other 0.5% is made up of small amounts of many other elements such as neon, iron, silicon, magnesium and sulfur. The sun shines because it is burning hydrogen into helium in its extremely hot core. This means that as time goes on, the sun has less hydrogen and more helium.

4. What is known about stars? C. Nuclear reactions within the sun create large amounts of heat and energy 1. Immense amount of heat causes the Sun to glow D. Our sun is yellow 1. Stars also come in white, blue, and red 2. Some are dark and do NOT glow Why do you think stars are different colors?

5. What is known about stars? E. Parts of the Sun Structure of the Sun Video

6. What is known about stars? E. Parts of the sun 1. Convection Zone – currents of hot gases carry energy as they rise to the surface and then fall 2. Radiation Zone – where hydrogen atoms combine to create helium (nuclear fusion) 3. Photosphere – surface of the sun 4. Chromosphere – lower layer of sun’s atmosphere 5. Corona – outer layer of the sun’s atmosphere, reaches millions of km into space Corona ->

7. What is known about stars? II. Distances in Space A. Scientists use kilometers on Earth to measure distance B. Astronomical Units (AU) measure distances between planets C. Neither are big enough to measure outside of our solar system, scientists use a unit based on the speed of light

8. What is known about stars? 1. This is called light years 2. In one year light travels as far as 9,500,000,000,000 kilometers Write this number in word-form. 3. used to measure distance in space

9. What is known about stars? D. Closest star to Earth (other than sun) – Proxima Centauri 1. It takes 4.3 years for light from this star to reach Earth E. Some stars are much further away 1. Cassiopeia A is 11,000 light years away F. It takes 8 minutes for light from our sun to reach the Earth

10. What is known about stars? Why is looking at the stars like looking back in time?

11. What is known about stars? III. The Properties of Stars A. Stars are grouped by brightness, color, and size 1. brightness and color can depend on the temperature of the star

12. What is known about stars? B. Star’s brightness depends on how big it is, how hot it is, and how far away from Earth it is 1. The bigger and hotter it is, the more light it gives off 2. The proximity to Earth affects how bright it is to people Why does proximity affect brightness?

13. What is known about stars? C. The color of the sun is determined by temperature CoolestHottest red -> orange -> yellow -> white -> blue-white

14. What is known about stars? D. Size of stars 1. smallest can be smaller than Earth Make a predictiction, how many times greater is the diameter of the largest known star? Size of Stars video

15. What is known about stars? 2. The largest known star is VV Cephei a. 2,644,800,000 km in diameter b. 1900 times the diameter of our Sun c. 649,800 times the diameter of Earth 3. Polaris, “North Star”, varies in size How can a star vary in size from day to day?

16. What is known about stars? Polaris is actually a group of 3 stars which move around each other in space.

17. What is known about stars? IV. Constellations and Galaxies A. Constellation – stars that seem to be in a group List at least 3 constellations which you have heard of before

18. What is known about stars? 2. People in ancient times made up stories about constellations and how they got up in the sky

19. What is known about stars? 3. From Earth the constellations look like groups, really they are NOT near each other

20. Star Charts A star chart is a map of the night that enables you to locate stars, celestial bodies, other planets and different patters of stars called constellations. When using a star chart be sure that you have a correct map in accordance with your location and date. Generally star charts are different for Northern and Southern hemispheres.

21. Star Charts To use the Star Chart, find the date. The correct date needs to be on the bottom. Put the chart over your head and locate the stars.