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- 2036 - Exoplanets - Is there life on other planets? Could life exist elsewhere in the galaxy, in the universe? Is life on Earth unique? Are there other forms of life elsewhere? Astronomers have studied some 150,000 stars to date and found 4,000 planets orbiting these stars. What are the chances that life exists on one of these planets?
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-------------------------- - 2036 - Exoplanets - Is there life on other planets? -
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- Could life exist elsewhere in the galaxy, in the universe? Is life on Earth unique? Are there other forms of life elsewhere?
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- Here on Earth there are thousands of different species of mammals. Millions of different plants. Billions of different bacteria and virus. So, life elsewhere might be different still.
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- In our search, astronomers have a satellite that is looking at a single spot in the sky. The area the size of the full moon. Astronomers have studied over 150,000 stars in this field of view and found 4,000 planets orbiting these stars. What are the chances that life exists on one of these planets?
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- This small spot in the sky contained 4,000 planets. These are the ones we could readily detect because they pass in front of their star. There must be many others that are beyond our ability to detect. That is just one small spot in the sky. And, just in our galaxy. There must be billions of galaxies and trillions of planets? Billions of these planets must contain life forms of some sort. It is just in the numbers. But, we have not found number one yet, besides us.
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- Life must be out there somewhere, but, there is no evidence to date. Our Milky Way Galaxy likely contains 10 billion habitable planets or moons. How do astronomers come to this amazing conclusion?
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- Habitable planet means one that has the environment similar to Earth. These planets are somewhere between gas giants like Neptune and rocky planets like Mercury. Venus , Earth, and Mars that lie in our Sun’s habitable zone.
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- For astronomers planets orbiting stars are very hard to see. At interstellar distances planets may pass in front of the star in our line of sight but they get lost in the glow of their host star.
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- However our technology is so good that a planet transit in front of the star can be detected by the slight amount of dimming of the light depending of the size of the planet compared to the star. This detection method has had tremendous success finding over 4,000 transit planets.
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- Another method uses the radial velocity of the host star. As the planet, or planets, orbit they pull the star towards and then away from us each orbit that they complete. When they get pulled away from us the light gets redshifted. When the star is pulled towards us the light is blue shifted. The bigger the shift the bigger the planet. This is called the Doppler Shift method and it has detected over 1,300 planets.
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- With this data astronomers can calculate the mass of the planet as well as the volume of the sphere. This in turn is used to calculate the density. Is this a rocky planet , a liquid water planet, of gaseous or ice planet? For those planets where the calculations tells us liquid water could exist on the surface then we call that a “habitable” planet and we focus on gathering more data
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- Gliese 581 is a dwarf red star some 20 lightyears from Earth. Up to 5 planets orbit this star. You have noticed that the planet designation is the name of the star followed by a,b,c,d,e,or f starting with the planet closest to the star then moving outward. Gliese 581c orbits near the inner edge of the habitable zone.
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- Planets Gliese 581d and 581g may be more Earth like . 581g is just 0.13 AU away from the dim red dwarf, but receiving the same amount of energy as Earth. Its mass is 2.2 Earths. It is tidally locked with one side always facing the sun. This is like our Moon which is tidally locked with Earth. Gliese 581g could develop a permanent ocean on the hemisphere facing the star.
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- We are looking for planets earth size or smaller than Neptune size. Neptune is 17.1 Earth mass, Uranus is 14.5. Earth mass. Neptune is 1.6 Earth radii.
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- Kepler 62 has 5 confirmed planets. It is 1,200 lightyears from the star. Two of these planets orbit in the habitable zone. Both are 1.5 times the size of the Earth.
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- Gliese 667 is a triple star system. GlidesC has at least 3 planets orbiting in its habitable zone. One of the planets circles in only 28 days. But, because the star is a red dwarf there is likely liquid water on its surface. It collects 90% the light that our Earth receives from the Sun.
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- Kepler 438b orbits in 35 days. It is 1.4 times the mass of the Earth with surface temperatures between 32F to 140 F. It also maintains a strong magnetic field that should protect it from radiation. It too might be inhabited?
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- Gliese 1132b is 1.2 Earth radii and 1.6 Earth mass. It is between being a rocky planet and sub-Neptunian. But, its surface temperature is 460 F.
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- Kepler 425b. Is 1.5 Earth radius. It is farther from its star but it is a brighter star so it gets about the same energy that Earth does. We could grow a vegetable garden there. It takes 385 days to circle its star. However, it’s star is 1.5 billion years older than our Sun which is only 4.5 billion years old
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- Detecting a new living world would forever change our views of biology. We would have a new dimension to view life in our universe.
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- HERE ARE SOME OTHER REVIEWS AVAILABLE:
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- 2030. - Exoplanets in an expanding Universe. The Hubble Constant is a measurement of how fast the Universe is expanding. For every star there is a 50% chance there is at least one planet orbiting it. If we discover a planet with a large amount of oxygen in its atmosphere there must be living organisms living there.
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- 1912. Exoplanet Proxima b. It is only 25 trillion miles away. The star Proxima has a planet in orbit that could likely have liquid water on its surface.
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- 1874. Will we likely find life on exoplanets and exomoons. Over 4,000 discoveries. This review is a summary of what we have learned to date. This Review lists 13 more reviews from #1788 to. #555 that explore these planets and moons.
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- 1833. Exoplanets are starting to reveal their secrets.
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- 1669. How many planets are there? How do we do the math to determine the mass of an exoplanet.
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- There are 300,000,000,000 stars in our galaxy.
- There are 2 trillion galaxies in the Observable Universe.
- So, that is 200,000,000,000,000,000. ( 2 * 10^17 stars )
- Half of these stars have at least one planet.
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------------------------- Friday, March 9, 2018 --------------------------------
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