1. Warm-up
What is the shape of the Earth’s orbit around the sun?

2. The Sun

3. Comparison with Sun

4. What is a Star?
Enormous spinning ball of hot and luminous plasma held together by gravity
Largest 1000X bigger than Sun
Smallest not much bigger than Jupiter
Mass of Sun is defined as 1 solar mass

5. Apparent magnitude- the brightness of a star as seen from Earth
Absolute magnitude (luminosity)- the brightness that a star would have a certain distance from Earth
Parallax- an apparent shift in the position of an object when viewed from different locations

6. Hertzsprung-Russell Diagram
Shows relationship between mass, luminosity, temperature, and diameter of stars
Vertical axis - absolute magnitude
Horizontal axis – temperature and spectral type

7. Hertzsprung-Russell Diagram
Main sequence- contains 90% of stars

8. Red giant- a large, reddish star late in its life cycle
White dwarf- a small, hot, dim star that is the leftover center of an old star

9. Blackhole- an object so massive and dense that even light cannot escape its gravity
Supernova- a gigantic explosion in which a massive star collapses and throws its outermost layers into space

10. The Sun 99% of mass in Solar System Center 13X density of lead!
Gas throughout (inner is plasma)
Surface temperature around 5000 K (8540° F)
How is the surface at 5,000K but the corona at 1,000,000K? Density is much, much less – like the Earth’s outer atmosphere. Very high temperature but can’t find a particle to transfer the energy.

11. The Sun Nuclear fusion of hydrogen to helium
Currently, about 70% hydrogen, 28% helium
Stream of charged particles to 100 AU called solar wind

12. Fusion
Fusion - Combining of two hydrogen atomic nuclei into one bigger helium nuclei
Occurs in Sun’s core
High temperature + high pressure

13. Fission
Fission - Splitting of one heavy atomic nuclei into two or more smaller, lighter atomic nuclei
Earth’s core

14. The Sun Convective zone- layer of the sun where gas convection happens
Radiation zone- dense region where highest energy radiation is given off

15. Sunspots- a dark area on the photosphere of the sun that is cooler than the surrounding areas and that has a strong magnetic field
Core- where fusion reactions take place in the sun
Corona- sun’s outer atmosphere
Chromosphere- thin outer region
Photosphere- visible part of the sun

16. Electromagnetic (EM) waves –
classified by wavelength or frequency.
Most blocked by Earth’s atmosphere – especially X-rays and gamma rays.