--------- #1274 - In 1000 Planets is there One Like Ours?
- New Space Telescopes have located over a 1,000 planets orbiting stars in other solar systems. Are any of these solar systems like ours? Are there terrestrial planets like Earth in these far off solar systems? This review brings you up to speed with these questions.
- Attachments - Kepler Space Telescope
- Astronomers were arguing for several years as to whether there were 8 or 9 planets in our Solar System. Finally, a decision was made and Pluto got butted out of the Solar System and put into the Kuiper Belt with several other Dwarf Planets. Some of these other Dwarf Planets are larger than Pluto.
- While these astronomers were loosing planets in our Solar System there were other astronomers adding planets, exoplanet, that they have found in other solar systems in our Milky Way Galaxy. Out of over a thousand candidates, there are over 500 that have been identified as planets orbiting other stars.
- The Kepler Space Telescope continuously monitors over 156,000 stars in a single spot in the sky. It has discovered to date 1,235 new planet candidates. In each case careful study is needed to confirm a planet candidate is actually a planet.
- Prior to 1995 there were no known planets outside our own Solar System. Kepler is staring at 0.0001% of the sky and has found 1,235 to date. This turns out to be an exotic assortment of planets. In fact, there are an exotic assortment of other solar systems. There are rocky planets like our Mercury, Venus, Earth and Mars and there are gaseous planets like Jupiter, Saturn, Uranus , and Neptune.
------------------- 67 ----- exoplanet are Earth-size
------------------ 288 ---- are about double Earth-size
----------------- 662 ---- are Neptune-size
----------------- 184 ---- are Jupiter-size
- By measuring the distance of the planet’s orbit about the star, astronomers can calculate the temperature of the planet and predict if the planet could contain liquid water. 53 or the 1,200 candidates could likely have liquid water.
- The Neptune-size and Jupiter-size planets are likely gaseous planets. Astronomers used to think that no like could exist there. However, after discovering moons around our own Jupiter and Saturn that have the possibility for life means that life around the other giant gaseous planets can still exist.
- Our own galaxy contains over 200,000,000,000 stars. Even if we ignore the life on moons the number of possible planets with life potential is staggering If 30% of solar systems have an Earth-size planet then there are over 60,000,000,000 Earth-size planets n our one galaxy alone.
- The technology that has made the difference for planet-hunting telescopes is to put them in space with extremely sensitive light detectors. These detectors can record the slightest dip in a star’s brightness as a planet passes in front of the star. These detectors are the same charge-coupled devices, CCD’s that are used in digital cameras. Kepler uses a 95 mega pixel camera that is so sensitive it can detect a 0.01% change in brightness..
- In 1995 the first exoplanet, 51 Pegasi b, was discovered. It is a Jupiter-size planet orbiting just 5 million miles form the star ( We orbit 93 million miles from our star.) Our Jupiter is 480 million miles from the Sun and takes 480 years to complete a single orbit. 51 Pegasi was discovered using a different technology. Its discovery used the Doppler effect measuring the wobble of the star caused by the gravitational tug of the plane, or planets, orbiting it
- The Doppler method only works well for large planets, Jupiter-size planets, that have enough gravity to move the star they are orbiting. To find smaller planets, Earth-size planets, a new method was needed. Kepler’s “photometry transit” method was the next leap in technology.
- Kepler’s spacecraft trails behind Earth’s orbit with a 55 inch telescope. The sensitivity of the CCD’s could measure light changes down to 20 parts in a million. Launched in March 2009 the 2,320 pound spacecraft contains 22,000 separate parts. The CCD array was 11 inches square, 95 mega pixels, kept at -120 F temperature to detect very low light levels. It is called an Orthogonal Parallel Transfer Imaging camera. It can detect a moth in fron of a lit window 1,000 miles away.
- The telescope stares at one spot in the sky that has over 4,000.000 stars in its field of view. but, it concentrates on only 156,000 selected stars. These stars were chosen for their relative stability in brightness. The small spot in the sky is between the Constellations Cynus the Swan and Lyra the Harp. The field of view extends from 600 to 3,000 light years. The diameter of the field of view is equivalent to 27 full moon diameters.
- When a star dips in brightness it could be caused by sunspots, a sun flare, or even eclipsing binary stars. Planets move across the face of a star in a few hours. Sunspots rotate with the star and normally take days or weeks to change in brightness. If more than one planet is orbiting the star the timing of the orbits can be used to calculate the masses of the planets. Once masses are known the density of the planets can be calculated. The next step is to measure the chemistry in the planet’s atmosphere.
- With a light spectrum through a planet’s atmosphere a chemical signatures for life can be found. Astronomers are looking for oxygen, water vapor, and carbon dioxide. So far planet densities are all over the map. The data displays astounding diversity. Every 2 months Kepler telescope download 60terabytes of data. Anyone can get to this data on the Kepler web site. ( Keplergo.arc.nasa.gov/ ). Even us amateurs can recover light curves of a star we are interested in.
- The detected light curves are proving so sensitive they can detect sound waves flowing through the star. This is like ultrasound looking at the fetus of a baby about tot be born.
- One star, KIC10195926, was found to pulsate on two axes of symmetry at once. The northern and southern hemispheres of the star spin at different rates and trade rates back and forth.
- Another star appears to be orbiting a Blackhole. The intense gravity is lensing he starlight into a beam the briefly sweeps by Earth once every orbit.
- There are binary stars orbiting so closely heat white-hot plasma flows between them.
- There are stars with immense sunspots that indicate strange rotations.
- There are White Dwarf stars in eclipsing orbits.
- Transient planet WASP-10b was detected only 6% larger than Jupiter yet 3 times more massive. Therefore, as a gaseous planet it has 3 times more density than Jupiter.
- Planet Kepler 10b is 1.4 times the diameter of Earth. However, temperatures reach 3,000K. Hot enough to melt iron.
- Kepler 11 is a 6 planet solar system. The outer planets are gaseous and tin inner planets appear to be denser. But, 5 of the 6 planets orbit their sun in orbits smaller than Mercury’s.
- Planet GJ1214b is 3 times Earth-size and 300F hotter but contains liquid water because it atmosphere is so dense. It orbits 1,300,000 miles from its sun.
- Planet HD80606b is Jupiter-size and has an elongated orbit. It swings within 3,000,000 miles of the sun and out to 81,000,000 miles. The temperature changes from 1,000F to 2,200 F n 6 hours. Winds reach 10,800 miles per hour.
- There is so much to learn. An announcement will be made shortly, stay tuned.
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707-536-3272, Sunday, July 17, 2011
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