The Sun

1. The Sun

2. IV. The Sun • A. All life on Earth depends on the energy that comes from the star in the center of our solar system. • B. Energy produced by the Sun is due to hydrogen atoms fusing together to produce helium atoms. • C. The Sun is composed of 3 layers: • 1. Photosphere – innermost not as hot • 2. Chromosphere – transition zone • 3. Corona – largest & hottest layer

3. V. Sun Surface Features • A. The sun appears to be a smooth layer but has many surface features including: • 1. Sun spots – cooler areas • 2. Prominences – arching columns of gas • 3. Flares – gases shooting straight upward • 4. CMEs (coronal mass ejections) – auroras All due to magnetic field & reactions across the Sun.

6. Solar Eclipse • Occurs when the Sun, Moon, and Earth line up • Can only happen during a New Moon • Generally, they occur every 2-5 years

7. Lunar Ecipse • Occurs during a Full Moon • Occurs when Moon, Earth, and Sun are directly aligned. • Next one is October 8, 2014

8. Auroras

9. Sun Cycle • Cycle lasts about every 11 years • Done so by counting sunspots • Sunspots may exist anywhere from a few days to a few months, but they eventually decay, and this releases magnetic flux in the solar photosphere

10. Solar Flares • The sun unleashed a powerful solar flare late Monday (Oct. 22), releasing waves of radiation into space that have already caused a short radio blackout on • Solar flares are caused when magnetic activity ramps up in certain patches, called sunspots, on the surface of our sun

12. I. Constellations • A. Constellations are patterns of stars that are named as a group. (88 exist in our sky) • B. All the constellations we see in the sky are part of our galaxy (large collection of stars, gas, & dust held together by gravity), the Milky Way Galaxy

13. II. Absolute & Apparent Magnitude • A. The actual brightness of the star refers to the stars absolute magnitude. • B. How bright the star actually is to the viewer on Earth is called the apparent magnitude • Apparent Magnitude does not equal absolute magnitutde

14. III. Measuring in Space • A. Distance in space is measure in light years or the distance light travels in one year (9.5 trillion km) • Used to estimate the distance of stars from Earth • The distance shifts depending on the motion/position of Earth as it orbits (parallax)

15. Astronomical Unit: the distance between the Earth and the Sun • 149 597 871 kilometers

16. VI. Properties of Stars • A. Basic properties of stars include: • 1. Diameter • 2. Mass • 3. Brightness • 4. Energy Output (luminosity) • 5. Composition – 73% hydrogen, 25% helium • 6. Surface Temperature – appears different due to very slight composition differences

17. VII. Classifying Stars • A. Hertzsprung & Russell Diagram shows the relationship of temperature & brightness among stars • B. Main Sequence(90%) vs. Dwarfs & Giants (bright) • Temperature: x axis • Absolute Magnitude: y axis

19. IIX. Life of a Star • Scientists theorize that a star goes through a few steps (as hydrogen depletes) • 1. Nebula – ball of gas & dust • 2. Main sequence – pieces of nebula are pulled together due to gravity, force increases energy/temperature • 3. Red Giant vs. Red Super Giant – when hydrogen begins to deplete outer layer cools & expands, (if large sequence is more quick & violent) • 4. White Dwarf vs. Neutron Star or Black hole – outer layers cool & escape to space leaving hot dense core

21. IX. Galaxies • A. Galaxies are groups into clusters. • B. Types of galaxies: • 1. Spiral Galaxies • 2. Elliptical Galaxies – football • 3. Irregular Galaxies – small irregular

23. X. Gravitational Pull • A. Every 2 bodies in the universe attract each other with a force that is proportional to the product of their masses. • In other words gravitational force depends on their masses & the distance between the 2 bodies • Gravity increase with larger mass & closer proximity Think about 2 magnets