1. Lecture 12: Searching for planets orbiting other stars. I. Light & Telescopes Direct detection of planets around other stars. Light and telescopes - optics. Challenges and promises of direct detection.

2. Direct Detection of Planets Direct detection is challenging because of the technical limits of telescopic observations

3. Light & Matter interact in 4 basic ways

4. The nature of light Light - electromagnetic waves that have: Wavelength Frequency Speed … and Energy

5. The nature of visible light Obeys the inverse-square law:

6. Direct Detection of Planets Direct detection is challenging because of the technical limits of telescopic observations

7. Direct Detection of Planets The best case to-date of a planet-like system detected in infrared light:

8. Light and Telescopes - Optics Optics - creating an image & collecting light:

9. Light and Telescopes - Optics Another function: Resolution

10. Light and Telescopes - Optics Resolution - the ultimate limitation comes from the wave properties of light:

11. Light and Telescopes - Optics Resolution - the ultimate limitation comes from the wave properties of light:

12. Light and Telescopes The challenge of detecting planets: Spectrum of the Sun, and as it is reflected by 3 of the planets:

13. Light and Telescopes Trying to ‘see’ the planet in the strong glare of the star:

14. Telescopes - the Atmosphere Atmospheric ‘seeing’ Before After correction

15. Telescopes All large telescopes are reflectors:

16. Telescopes The largest today - the Keck telescopes are composite mirror reflectors (D~ 10m): They also form a pair - an interferometer.

17. Telescopes Harvard is a partner in the construction of the largest new telescope: The Giant Magellan Telescope (D ~ 25 m)

18. The Laser Astro-Comb

19. Main points to take home: 1) Visible light: form of electromagnetic energy (radiation) to which our eyes are sensitive. 2) Energy & power vs. color 3) Four basic ways light and matter interact. 4) Telescopes: optics & 2 types of design. 5) Angular Resolution vs. light gathering