Nick Weber ZONES OF HABITABILITY AROUND NORMAL STARS

GOALS Search for life beyond Earth Looking to analyze the spectra of Earth-like planet atmospheres. Habitable Zones!!

TYPES OF PLANETS Terrestrial Planets Such as Mercury, Venus, Earth, and Mars Comprised of rock and metal and have thin atmospheres Giant Planets Such as Jupiter, Saturn, Uranus, and Neptune Composed of hydrogen and helium Have massive atmospheres and liquid interiors

HOW DO WE FIND THESE PLANETS? Radial Velocity Uses gravitational influence of planets on stars Many disadvantages 100 giant planets have been discovered using this method since the first extra solar planet was discovered in 1992.

DISAPPOINTING RESULTS Terrestrial planets orbiting stars have too low of a mass to be detected. Chances of finding earth-like planets around stars with known giant planets is very slim. Next step?

PLANET TRANSIT DETECTION As a planet passes in front of a star, it reduces the level of brightness of the star. Advantages: Able to detect terrestrial planets!! Disadvantages: Planet needs to be aligned perfectly.

DIRECT DETECTION OF LIGHT Direct detection of reflected or emitted light from a planet itself is the only method that allows for the study of planet atmospheres and surface characteristics. Most difficult method, light from parent star makes it almost impossible to detect objects close to the star. Direct Detection image of a planet orbiting the star Gliese 229 taken with the Hubble telescope

HOW TO IMPLEMENT THESE METHODS? Hubble Telescope

FUTURE In a 2002 article by Seager, he states that the future of earth detection lies in ESA’s Darwin project, and NASA’s Terrestrial Planet Finder (TPF)

ESA DARWIN PROJECT Darwin would operate with 4-9 spacecrafts, operating in a hexagon shape with a central receiving unit. Designed to directly detect Earth-like planets and search for life on these planets. Needed to be very exact What happened? One of Darwin’s telescopes via esa.int

NASA TERRESTRIAL PLANET FINDER Block light from parent star to find much smaller dimmer planets. Would be able to characterize the surfaces and atmospheres of new planets. In may 2004 it was approved by NASA Where is it? Terrestrial planet finder concept via NASA.gov

WHAT DOES THIS SAY ABOUT THE SEARCH FOR EARTH-LIKE PLANETS?

THERE IS HOPE! KEPLER SPACE OBSERVATORY Kepler is a space observatory launched by NASA to discover Earth-like planets orbiting other stars. Uses transit method As of January 2013, there was a total of 2,740 planets discovered (candidates). Kepler Telescope from ballaerospace.com

48 CANDIDATES FOUND IN HABITABLE ZONE!! Image via Penn StatePenn State

IF WE HAVE MANY POSSIBLE HABITABLE PLANETS, WHICH ONES DO WE ANALYZE? Planets cannot be too young or too old Need to avoid stars younger than a few hundred million years because it is likely that life has not emerged yet Planets need to have spent at least hundreds of millions of years in the Habitable Zone. Plate tectonics could also be critical to planets being able to sustain life. We are able to see if planet has plate tectonics.

COULD BE LONG SEARCH There are many signs that earth’s ability to support life is extremely rare. Statistical Simulations have shown that 98.5% of randomly generated versions of our solar system would result in severe changes to our climate, making the Earth uninhabitable. Technology is always advancing.

CLOSING POINTS Major progress in last decade We are only searching for life as we know it. Planet detection is not a big social priority and still too expensive. Still don’t know what is out there!!

BIBLIOGRAPHY Horner, J., and B.W. Jones. "Determining Habitability: Which ExoEarths Should We Search for Life?" International Journal of Astrobiology 9.04 (2010): Print. Kasting, James F. "Habitable Planets: What Are We Learning from Kepler and Ground- Based Searches?" Astrobiology 11.4 (2011): Print. Michele, Johnson. "NASA - National Aeronautics and Space Administration." NASA. N.p., 7 Jan Web. 15 Apr Seager, S. "The Search for Extrasolar Earth-like Planets." Earth and Planetary Science Letters (2003): Print.