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Transit Tracks: Finding Extrasolar Planets a science & math activity

Transit Tracks: Finding Extrasolar Planets a science & math activity. “transit”. “transit”. “transit”. What’s this?.

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Transit Tracks: Finding Extrasolar Planets a science & math activity

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  1. Transit Tracks:Finding Extrasolar Planetsa science & math activity

  2. “transit”

  3. “transit”

  4. “transit”

  5. What’s this?

  6. A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and Earth, so that Venus blocks a small spot of the Sun’s disk. Since the Sun is over 100 times larger in diameter than Venus, the spot is very small indeed.

  7. Account of Jeremiah Horrock’s observations of the transit of Venus

  8. Imagine you have a light sensor aimed at the star. What would the transit of a book look like if you made a graph of light intensity vs time? BRIGHTNESS 0 TIME 0

  9. Like this? BRIGHTNESS 0 TIME 0

  10. What would the transit of a planet look like if you made a graph of light intensity vs time? 0 TIME 0 BRIGHTNESS

  11. Perhaps like this?Such graphs are called “light curves.” How would a planet’s size and orbit period affect the transit—light curve? 0 TIME 0 BRIGHTNESS

  12. The light curve can lead to finding the SIZE of the planet and its DISTANCE from the star.Why would those characteristics be important?

  13. Is there a relationship between the planet’s period (time for one orbit)and how its distance from the star?

  14. Kepler’s 3rd Law

  15. A3 = p2

  16. Kepler 4-b

  17. Planet’s Size: Deducing the Planet’s Radius from Transit Data Ap/As = Z Converting to a percentage 100 ( Ap/As) = Z% 100 (π rp2 /π rs2) = Z% 100 ( rp2 / rs2) = Z% rp2 / rs2 = Z%/100 rp2 = rs2 (Z%/100) rp = rs/10 √ Z% area of a circle = π r2 The Sun is about 100 times the radius of the Earth. rsun = 100 rearth Substituting: rp = 100 rearth/10 ( √ Z% ) rp = 10 rearth ( √ Z% )

  18. ( By permission Sternwarte Kremsmünster) A guy who’s thought a lot about planets

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