1. Worlds around Distant Suns Mini University June 16, 2003 Among the most significant discoveries of the 20th Century

2. our own Solar System Let’s begin with…

3. How Big Are OUR Planets?

4. How Big Is OUR Solar System?

8. And Where Is Pluto?

9. What about the Nearest Stars? try HAWAII! Alpha, Beta, and Proxima Centauri

10. Rainbows from Starlight Finding Planets around Other Stars

11. Doppler Shift I Doppler Shift II

12. Velocity of 51 Peg About 7 orbits in 30 days… The planet’s year is only 4.2 days long Physics comes in handy!

13. The Mass of the Planet A period of 4.2 days means the planet’s mass is about half the mass of Jupiter

14. How Big is the Orbit? ONLY 0.05 AU The Earth is 1 AU from the Sun Jupiter is 5 AU from the Sun Mercury is about 0.4 AU from the Sun 51 Peg’s planet is HOT HOT HOT!

15. A Planet around  Eridani  A planet orbits the star  Eridani at a radius of 3.2 A.U.   Eridani is similar to our Sun   Eridani is only 10.5 light years away  The planet is similar to Jupiter  The planet orbits  Eridani in 7 years Orion

16.  And has at least 3 planets terrestrial planets

17. Properties of KNOWN Extra-Solar Planets All are gas giants like Jupiter and Saturn Most are larger than Jupiter Many orbit close to their parent stars Some are in systems with multiple planets

18. So far, only large gas giants like Jupiter and Saturn have been found

19. Known Planets Are Close to Stars

20. Planets form as part of the process of star formation

21. Different Kinds of Planets Gas Giants Ice Giants Terrestrial Planets

22. Hot Jupiters These hot Jupiters form further out, and migrate inward as they eject smaller bodies from their planetary systems

23. normal star like our Sun 150 light-years from us "year" of only 3.5 days less than 7 million km from its own star gas giant like Jupiter hot, very extended hydrogen atmosphere planet is evaporating – with a “comet” tail Planets so close to their parent stars may not survive An Evaporating Planet

24. If the Earth lies in the same plane as the orbit of a planet we see a transit The planet passes across the face of the star Some of the starlight is blocked by planet and the star appears dimmer Planetary Transits

25. Pictures of Planets? Angular Resolution Infrared sensitivity Soon! We can now detect young planets the size of Jupiter as close as 6 A.U. from their parent stars!

26. Questions about Planets What size planets usually form? How far are planets from their parent stars? How many planets do stars have? What kinds of stars have planets? What kinds of weather and clouds do planets have?

27. Finding Life on Distant Worlds NASA is planning missions to find and study Earth-like planets around as many as 150 stars within 50 light-years. The Terrestrial Planet Finder will look for terrestrial-size planets in the "habitable zone“ TPF will search for atmospheric signatures, habitability, or life itself

28. Can we travel to new worlds? Within the lifetime of today’s children we will be able to send robotic spacecraft to visit our nearest neighbors At 10% of the speed of light (30,000 km/sec) travel time will be about 100 years Then wait another 10-20 years for the data to return

29. What will we find? The challenge of the next generation!

30. Kirkwood Observatory Open Every Wednesday evening Weather permitting When it’s dark…

31. Where to find Kirkwood

32. Websites of Interest  Indiana Astronomical Society  www.iasindy.org www.iasindy.org  National Optical Astronomy Observatory Image Gallery  www.noao.edu/image_gallery www.noao.edu/image_gallery  Space Telescope Science Institute  www.stsci.edu www.stsci.edu  Amazing Space  amazing-space.stsci.edu amazing-space.stsci.edu  NASA’s Astronomy Picture of the Day  antwrp.gsfc.nasa.gov/apod/astropix.html antwrp.gsfc.nasa.gov/apod/astropix.html  Astronomical Society of the Pacific  www.astrosociety.org www.astrosociety.org  The Stonebelt Stargazers  www.mainbyte.com/stargazers/ www.mainbyte.com/stargazers/