Exoplanets

1. Exoplanets "Somewhere, something incredible is waiting to be known.” - Carl Sagan

2. Other Worlds? For years people have wondered if other worlds exist outside our solar system. Epicurus (300 B.C.) “There are infinite worlds both like and unlike this world of ours. We must believe that in all worlds there are living creatures and planets and other things we see in this world.”

3. Nicholas of Cusa (1401-1464) and Giordano Bruno (1548 – 1600) Both men dispute the Sun’s position as unique and the center of the Universe. Bruno is burned at the stake for his belief that there are other stars and Solar systems like our own.

4. Nicholas Copernicus 1543 He is the first person to suggest that the Sun, not the Earth is the Center of the Universe. He went on to suggest that the planets, including the Earth, orbit the Sun. These ideas were very controversial.

5. GallileoGallilei Gallileo introduces the telescope to Astronomy. He discovers the moons of Jupiter and craters on the Moon. He is forced by the Vatican to recant his findings. He spends the last 10 years of his life under house arrest.

6. Christiaan Huygens (1625-1695) He publishes Cosmotheros a book that speculates what life would be like on another planet.

7. Thomas Wright (1750) He was the first to speculate that the Milky Way is actually made up of many stars.

8. William Herschel (1781) He discovers the first new planet since ancient days and gave it the unfortunate name Uranus. His discovery was made possible because of improved telescope design. The Newtonian telescope, using a mirror and a lens produces much clearer images.

9. It was difficult to make large, high quality lenses for Refractors. The weight of the lens itself would distort the lens and the image. A mirror was much easier to make very large as it could be supported equally in all areas. All of the largest telescopes are Reflectors, including Keck, Hubble and Palomar.

10. Hubble Space Telescope Above the turbulent atmosphere, this reflecting telescope can capture amazing details.

11. Pillars of Creation This was one of the first photos published from the Hubble telescope. It is a small part of the Eagle Nebula. The tiny balls of gas starting to coalesce in the photo are larger than our solar system.

12. The Eagle Nebula The Eagle Nebula( M16), also known as the Star Queen Nebula,is a young open cluster of stars in the constellation Serpens, discovered by Jean-Philippe de Cheseaux in 1745-46. The Pillars of Creation is in the middle of this picture.

13. Keck Telescopes These twin telescopes are atop the peak of Mauna Kea in Hawaii. Their mirrors are made of smaller hexagonal mirrors that are focused using computers.

14. Uranus This photo taken with the Keck telescope shows Uranus’ faint ring and two of its moons.

15. Capt. W.S. Jacob (1855) Found orbital anomalies in the Star 70 Ophiuchi. He claims the wobbles are caused by a planet orbiting this star. This begins a 140 year history of false alarms. No planet was actually discovered.

16. A.A. Michelson and Francis Pease (1920) They used a stellar interferometer to measure the diameter of the Star Betelgeuse. This instrument, later, becomes very important in discovering exoplanets. This device projects two parallel beams of light from a star into a telescope allowing the astronomer to calculate the diameter of the star the light is coming from.

17. Edwin Hubble (1925) Using the Hooker 100” telescope on Mt. Wilson in California Hubble proves that there are other galaxies besides the Milky Way. By observing the red shift in stars in certain sections of the sky he was able to prove that those stars were far beyond the Milky Way. Overnight the Universe became infinitely huge.

18. Dr. Frank Drake (1960) He creates an equation that predicts the number of alien civilizations in our galaxy that we may come into contact with. His answer is 2.31. His work is considered a groundbreaking method of pondering the likelihood of intelligent life in the galaxy.

19. Star Strek (1966) The show introduces extraterrestrial life and planets into popular culture. Show creator Gene Roddenberry later endorses the star 40 Eridani A – which may have an earthlike planet orbiting around it as the home of the Vulcans.

20. Hubble Space Telescope (1990) This revolutionary telescope is launched in April. This instrument will later aid in the detection of exoplanets by measuring the dimming of the light of a star when a planet passes between the star and the sun. Hubble will be the first telescope to actually take a visual picture of an exoplanet.

21. AleksanderWolszczan and Dale Frail (1992) They discover two rocky planets orbiting PSR 1257 +12, a neutron star. Because the planets are constantly bombarded by radiation, they cannot possibly support organic life.

22. Planet PSR B1620 -26b 1992 This is the first planet found to orbit a binary system composed of a pulsar and a white dwarf. The planet is two and half times the size of Jupiter and takes over 100 years to orbit its two parent stars. This is the first planet to also be found in a star cluster.

23. Michael Meyer and Didier Queloz (1995) First to discover a planet orbiting a main sequence star. (51 Pegasi) The planet which is half the size of Jupiter orbits so close to its parent star that it nearly grazes its surface. No one knows how it can exist so close to its star. Total number of exoplanets discovered = 4

24. Multiple planets 1999 Researchers from San Francsisco State and the Harvard-Smithsonian institute for Astrophysics discover a 2nd and 3rd planet orbiting the star Upsilon Andromedae. Total number of exoplanets = 31

25. First transiting exoplanet observed (1999) A planet is observed passing in front of star HD209458. The Hubble space telescope was used to identify the gases sodium and a large tail of carbon, hydrogen and oxygen streaming from the planet.

26. HD 28185 b (2001) This planet orbits about the same distance from its star as the Earth does. This was the first planet to be found in the habitable zone. It is 6 times the size of the Earthand likely a giant gas planet. It is possible that one of its moons could be Earth-like. Total number of exoplanets = 62

27. Iota Draconis Astronomers discover a planet orbiting the giant star Iota Draconis. Iota Draconis is 13 times the diameter of the Sun and 40 times brighter. It is the first time that a planet has been found to orbit a giant star. Total number of exoplanets discovered is 96

28. Spitzer Space Telescope The Spitzer Space Telescope and the Canadian Space Telescope MOST were placed in orbit in 2003. Spitzer’s infrared ability will be used to spot many exoplanets in the future. Total exoplanets discovered = 121

29. French CoRoT Space Telescope - 2006 This telescope, launched in December, will be able to detect planets that transit their host stars. Total exoplanets at this time is 209.

30. Planet Hd189733b NASA’s space telescope Spitzer found water vapor in the atmosphere of this planet. (2007) This is the first time that water had been discovered in an exoplanet. Total number of exoplanets discovered = 271

31. 2008 Two separate groups of Astronomers release the first ever visible light images of an exoplanet. They use Hubble, Keck and Gemini. The planet Fomalhautb is thought to be 3 times larger than Jupiter. Total exoplanets discovered = 332

32. 2009 Kepler Space Telescope NASA launches the space telescope Kepler in March. Kepler observes thousands of stars at once looking for transiting Earth-like planets. Total exoplanets discovered = 374

33. Kepler-11 is a sun-like star around which six planets orbit. At times, two or more planets pass in front of the star at once, as shown in this artist's conception of a simultaneous transit of three planets observed by NASA's Kepler spacecraft on Aug. 26, 2010.

34. Current Results Current number of planets discovered is 841 with 2,781 to still be confirmed. Most are as large or larger than Jupiter. White dwarfs, Super massive stars along with red dwarfs, and main sequence stars all have been found to harbor planets. Kepler currently has a list of over 2,000 planets to be confirmed. The planets listed range from larger than Jupiter, Jupiter size, Neptune size, super Earth’s, and Earth size planets

35. The team from ESO’s HARPS planet finder estimates that rocky planets not much bigger than Earth are very common in the habitable zones around faint red stars. The international team estimates that there are tens of billions of such planets in the Milky Way galaxy alone, and probably about one hundred in the Sun’s immediate neighbourhood. This is the first direct measurement of the frequency of super-Earths around red dwarfs, which account for 80% of the stars in the Milky Way.

36. Observations by NASA's Hubble Space Telescope have come up with a new class of planet, a waterworld enshrouded by a thick, steamy atmosphere. It's smaller than Uranus but larger than Earth.This super-Earth is about 2.7 times Earth's diameter and weighs almost seven times as much. It orbits a red-dwarf star every 38 hours at a distance of 1.3 million miles, giving it an estimated temperature of 450 degrees Fahrenheit.

37. An international team of scientists has discovered a potentially habitable super-Earth orbiting a nearby star. With an orbital period of about 28 days and a minimum mass 4.5 times that of the Earth, the planet orbits within the star's "habitable zone," where temperatures are neither too hot nor too cold for liquid water to exist on the planet's surface.The host star is a member of a triple-star system.The researchers found evidence of at least one and possibly two or three additional planets orbiting the star, which is about 22 light years from Earth.

38. NASA's Kepler mission has discovered 11 new planetary systems hosting 26 confirmed planets. These discoveries nearly double the number of verified Kepler planets and triple the number of stars known to have more than one planet that transits, or passes in front of, the star.The planets orbit close to their host stars and range in size from 1.5 times the radius of Earth to larger than Jupiter. "Prior to the Kepler mission, we knew of perhaps 500 exoplanets across the whole sky," said Doug Hudgins, Kepler program scientist at NASA Headquarters in Washington. "Now, in just two years staring at a patch of sky not much bigger than your fist, Kepler has discovered more than 60 planets and more than 2,300 planet candidates. This tells us that our galaxy is positively loaded with planets of all sizes and orbits.

39. Kepler-22b is the first planet that NASA's Kepler mission has confirmed to orbit in a star's habitable zone.The planet is 2.4 times the size of Earth, making it the smallest yet found to orbit in the middle of the habitable zone of a star like our sun.Kepler also has discovered more than 1,000 new planet candidates, nearly doubling its previously known count. Ten of these candidates are near-Earth-size and orbit in the habitable zone of their host star.

40. Located 20 light-years away, Gliese 581d is situated on the "outer fringes" of the Goldilocks zone, orbiting a red dwarf star. The planet may be warm enough and wet enough to support life in much the same manner as Earth. It might also contain a thick carbon atmosphere.

41. Dubbed a "waterworld" and located 42 light-years from Earth, GJ 1214b orbits near a red dwarf star about one-fifth the size of our sun. What makes this planet unique is that it appears to be primarily composed of water, GJ 1214b is 6.5 times the mass of Earth and 2.7 times wider, which classifies it as a "super-Earth." This planet also has a steamy atmosphere composed of thick, dense clouds of hydrogen

42. Kepler-62f, a super-Earth-size planet in the habitable zone of a star smaller and cooler than the sun, located about 1,200 light-years from Earth in the constellation Lyra. Kepler-62f orbits it's host star every 267 days and is roughly 40 percent larger than Earth in size. The size of Kepler-62f is known, but its mass and composition are not. However, based on previous exoplanet discoveries of similar size that are rocky, scientists are able to determine its mass by association.

43. The artist's concept depicts Kepler-62e, a super-Earth-size planet in the habitable zone of a star smaller and cooler than the sun.Located about 1,200 light-years from Earth in the constellation Lyra. Kepler-62e orbits it's host star every 122 days and is roughly 60 percent larger than Earth in size. Scientists do not know if Kepler-62e is a waterworld or if it has a solid surface, but its discovery signals another step closer to finding a world similar to Earth.

44. Doppler Shift. The first way to find a planet. A planet and a star will orbit around their center of mass. This means that stars will wobble or move a bit as a planet or planets orbit them. This wobble can be detected as a change in speed.

45. Astrometric Measurement This method also depends on the slight motion of the star caused by the orbiting planet. In this case astronomers are searching for the tiny displacements of the stars on the sky. The planets of our solar system have this effect on the Sun, producing a to-and-fro motion that could be detected by an observer positioned several light years away. Astrometric displacement of the Sun due to Jupiter as at it would be observed from 10 parsecs, or about 33 light-years

46. If a planet passes directly between a star and us, it blocks out a tiny portion of the star's light, reducing its brightness. Sensitive instruments can detect this periodic dip in brightness. From the period and depth of the transits, the orbit and size of the planetary companions can be calculated.

47. Gravitational Microlensing Light rays become bent when passing through space that is warped by the presence of a massive object such as a star. When a planet happens to pass in front of a star the planet's gravity will behave like a lens. This focuses the light rays and causes a temporary sharp increase in brightness and change of the apparent position of the star.

48. Direct Imaging Planets do not give off their own light. Observing them directly is very challenging. Missions such as Terrestrial Planet Finder will rely on advanced technologies in extending our vision.

49. Life on other worlds Once a planet is disovered the inevitable question is could it harbor life? People analyze the light coming from the planets atmosphere. They look for Carbon dioxide, water and ozone. Gliese 581 g seems to hold water.

50. Habitable Zone the habitable zone is the region around the star where we can expect to find liquid water at the surface. If the planet is too hot, the water becomes vapor and is lost from the atmosphere. If the planet is too cold, the water freezes. Either of these conditions would make a planet very inhospitable for life. The habitable zone for our Sun starts beyond Venus and ends before Mars.