1. Our sun is just a star…but it’s OUR star!

2. What are STARs? “…. balls of gas burning billions of miles away”

3. The Sun a main-sequence star a main-sequence star generates energy by nuclear fusion of H into He generates energy by nuclear fusion of H into He in a state of equilibrium (pressure out = pressure in/gravity) in a state of equilibrium (pressure out = pressure in/gravity) about 5 billion years old (middle- aged) about 5 billion years old (middle- aged)

4. Birth of a Star Nebula : swirling cloud of dust and gas that, if it begins to form ‘clumps,’ will begin to attract more matter due to gravity  protostar Nebula : swirling cloud of dust and gas that, if it begins to form ‘clumps,’ will begin to attract more matter due to gravity  protostar As protostar grows, the ‘clumps’ begin to condense, the pressure goes up, so heat also goes up As protostar grows, the ‘clumps’ begin to condense, the pressure goes up, so heat also goes up If heats up enough(18,000,000°F), then nuclear fusion begins and VOILA.. a star is born!! If heats up enough(18,000,000°F), then nuclear fusion begins and VOILA.. a star is born!!

6. Life Cycle of a Star=Stellar Evolution

7. The Sunlight We See Light travels at 186,000 mi/sec (300,000km/sec) Light travels at 186,000 mi/sec (300,000km/sec) The sunlight that is currently reaching the Earth was generated inside the sun about 100,000 years ago The sunlight that is currently reaching the Earth was generated inside the sun about 100,000 years ago WHAT?!? How can this be? It takes a VERY long time for a photon of light to get from the core to the surface because the sun is so dense

8. The 8-minute travel time to Earth by sunlight hides a many thousand-year journey that actually began in the core.

9. DAY and NIGHT… Light travels in straight lines so only half the world can be lit up by the Sun; the other half must be in darkness. …caused by rotation of the Earth on its own axis

10. Earth revolves around the sun

11. What causes the different seasons of the year? The Earth’s tilt Summer in the Northern Hemisphere Winter in the Southern Hemisphere Winter in the Northern Hemisphere Summer in the Southern Hemisphere

12. SUMMER WINTER The amount of heat received in any one spot is directly related to the angle at which it is received The greater the angle, the less concentrated are the sun’s rays The amount of heat received in any one spot is directly related to the angle at which it is received The greater the angle, the less concentrated are the sun’s rays

13. The Earth’s atmosphere absorbs some of the sun’s heat energy

14. (Daytime = nighttime) Longest Day Longest Night

17. Born under the sign of…

18. Constellation Quiz 1.What is changing at the same (annual) timescale that we are observing the changing zodiac?

19. Constellation Quiz 1.What is changing at the same (annual) timescale that we are observing the changing zodiac? 2.Do the constellations appear to change positions in the night sky as Earth travels around our Sun throughout the year?

20. Constellation Quiz 1.What is changing at the same (annual) timescale that we are observing the changing zodiac? 2.Do the constellations appear to change positions in the night sky as Earth travels around our Sun throughout the year? 3.Are the constellations themselves moving?

21. Constellation Quiz 1.What is changing at the same (annual) timescale that we are observing the changing zodiac? 2.Do the constellations appear to change positions in the night sky as Earth travels around our Sun throughout the year? 3.Are the constellations themselves moving? 4.What causes this apparent change in positions?

22. Constellation Quiz 1.What is changing at the same (annual) timescale that we are observing the changing zodiac? 2.Do the constellations appear to change positions in the night sky as Earth travels around our Sun throughout the year? 3.Are the constellations themselves moving? 4.What causes this apparent change in positions? 5.Do all stars appear in different positions at different times of the year?

23. Constellation Quiz 1.What is changing at the same (annual) timescale that we are observing the changing zodiac? 2.Do the constellations appear to change positions in the night sky as Earth travels around our Sun throughout the year? 3.Are the constellations themselves moving? 4.What causes this apparent change in positions? 5.Do all stars appear in different positions at different times of the year? 6.Why is Polaris the only star that appears “fixed”?