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Astronomy Lunch: Explore the Universe with Mars Rover

Join us for an engaging lunch to discover the wonders of space, meet faculty, and delve into the mysteries of the Mars Rover exploration. Learn about radiation, thermal energy, blackbody radiation, and more!

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Astronomy Lunch: Explore the Universe with Mars Rover

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  1. Survey of the UniverseTom Burbinetburbine@mtholyoke.edu

  2. Prospective Astronomy Majors Lunch Monday, March 4th12:15-1:10pmKendade 303 Meet the faculty, learn about the Mars Rover, and enjoy a delicious lunch.

  3. HW# 3 • Due Wednesday

  4. So why are some types of radiation dangerous? • Higher the energy, the farther the photons can penetrate • So gamma and X-rays can pass much more easily into your the body • These high-energy photons can ionize atoms in cells • Ionization means removes electrons from an atom

  5. Thermal energy • Temperature – average kinetic energy of particles • Higher temperature – more kinetic energy, particles moving faster • For examples, air molecules around you are moving at ~500 m/s

  6. Temperature scales • In America, we use Fahrenheit • Water freezes at 32 degrees F • Water boils at 212 degrees F • Everywhere else, they use Celsius • Water freezes at 0 degrees C • Water boils at 100 degrees C

  7. In Science • Temperature is measured in Kelvin • Zero Kelvin is absolute zero – nothing moves • Add 273.15 to the Celsius temperature to get the Kelvin temperature • 273.15 Kelvin = 0 degrees Celsius

  8. Blackbody • A black body is an object that absorbs all electromagnetic radiation that falls onto it. • Perfect emitter of radiation • Radiates energy at every wavelength

  9. http://www.astro.ncu.edu.tw/contents/faculty/wp_chen/Ast101/blackbody_curves.jpghttp://www.astro.ncu.edu.tw/contents/faculty/wp_chen/Ast101/blackbody_curves.jpg

  10. http://www.rap.ucar.edu/general/asap-2005/Thur-AM2/Williams_DoD_Satellites_files/slide0005_image020.gifhttp://www.rap.ucar.edu/general/asap-2005/Thur-AM2/Williams_DoD_Satellites_files/slide0005_image020.gif

  11. Wien’s Law • Wavelength of Maximum intensity of the blackbody curve peak = (2,900,000) nm T (Kelvin) • If T = 10,000 K, • λmax = [2,900,000/(10,000)] nm • λmax = 290 nm • 1 nanometer = 1 x 10-9 meters • λmax = 290 nm = 2.0 x 10-7 meters

  12. Power and Luminosity • Power is in Joules/second = Watts • Luminosity is the total light output

  13. Stefan-Boltzman Law • Emitted power per square meter of the surface = σT4 • Temperature is in Kelvin • constant is σ = 5.67 x 10-8 Watt/(m2K4) • If you double the temperature of an object, it will be 2*2*2*2 = 16 times more luminous • If you triple the temperature, it will be 3*3*3*3 = 81 times more luminous

  14. Hotter objects are more luminous (give off more light) • The luminosity of a blackbody rises as the temperature to the fourth power

  15. What we can learn from stars • Luminosity (emitted energy/second) of an star is proportional to T4 and the surface area of the star L= σAT4 (σ =5.67 × 10−8 W m−2 K−4) • The color of the star is related to 1/T Wavelength peak = [2,900,000 /T (Kelvin)] nm 1 nanometer = 1 x 10-9 meters

  16. Spectral lines give you information of the composition of the star

  17. Any Questions?

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