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----------------------------- 1912 - Exoplanets - Proxima b
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- When we found other dwarf planets outside the orbit of Neptune, we lost Pluto as a planet. Pluto became a Dwarf Planet along with Ceres and Sedna, and several others. Some of these Dwarfs were bigger than Pluto. We either had to enlarge the Solar , Systems with planets, or , create a new category of sub-planets.
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- Something else happened at the same time. These newly discovered orbiting objects displayed strange orbits indicating that some larger gravity pull was influencing their orbits. Several were inclined with steep angles above and below the plane of the eight Solar System planets controlled by the Sun’s gravity. Was there still a real 9th planet out there causing this?
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- Is there still an undiscovered planet in our Solar System? Planet 9?
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- A deep sky survey for objects beyond Neptune and beyond the Kuiper Belt was started. Observations and calculations that are today trying to locate the massive planet that could be causing these perturbations of orbits. The smaller objects can lead us to the bigger object.
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- Some of these smaller objects have orbits extending out 3,000 AU’s from the Sun (Astronomical Units are Earth-Sun distances). This orbit is a massively elongated ellipse that can only be explained by a strong gravitational pull existing beyond our current understood Solar System.
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- Astronomers are finding never-before-seen objects orbiting the Sun at these extreme distances. As their orbital parameters begin to be understood the interactions seem to fit the notion that another distant planet gravity pull is determining the newly discovered structure of our Solar System.
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- The closest star to our Sun is Proxima Centura. A mere 25 trillion miles away. This star has an Earth-size planet orbiting in its “ habitable zone”. That is: a planet having a temperature that could support liquid water on its surface.
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- 4.2 lightyears distance is not walk in the park, but, in astronomical terms that exoplanet is in our neighborhood. This planet was discovered indirectly by studying the light from the host star. The star wobbles causing color shifts in the light it is emitting. The back and forth notion of the star is caused by the gravitational pull of an orbiting planet, or planets. The calculations put the mass of this unseen planet at 1.3 times Earth-mass.
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- Called “ Proxima b”. The time for one complete orbit, the planet-year, is 11.2 days. The planet’s orbit is just 5 million miles from the star. The Earth is 93 million miles from its star. Mercury is 36 million miles from the Sun.
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- The star Proxima is smaller and cooler than our Sun. It is a Red Dwarf star, 12% the mass of the Sun and 1/600 the luminosity (0.15%). The planet Proxima b orbits close enough to allow liquid water to flow on its surface. It is also so close that its rotation is likely tidally locked, always facing the same hemisphere toward the star. This is similar how the Moon is tidally locked to the Earth. The size of this new planet is 1.43 times the diameter of Jupiter.
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- By the way these conclusions are from over 10 years of gathering data on Proxima Centura.
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- A key instrument in this study is the “spectrograph” Using a prism the light is split apart by wavelength. Each spectrum of wavelengths is a “ bar code” that can identify chemistry, how fast the star is moving , and in which direction. If the bar code is shifted to the blue end of the light spectrum the star is moving towards us, shifted to the red end it is moving away from us.
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- As a planet orbits the star these shifts have a wobble indicating the push and pull of the planet’s orbit shifting gravity. If repeats in a regular cycle it must be duration of the planet’s orbit. Proxima b repeats every 11.2 days.
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- Astronomers will be studying Proxima b for signs of life using every improving technology in scientific research. This most recent data came from observations lasting 60 days in a row, 20 minutes each night.
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- One disadvantage of a planet orbiting too close to its star is the effect of frequent flares. Our Sun flares as well. But, being closer could mean these bombardments of high energy radiation could blow away any of the planet’s atmosphere. It could radiate away any chance for life.
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- Red Dwarf stars live for 10 trillion years. Since it takes billions of years for complex life to evolve they have plenty of time. Our Sun will only last 5 billion more years.
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- There is likely a second planet in this solar system with a 60 day orbit, Proxima a.
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- The Kepler telescope has discovered 4,696 exoplanet candidates, 2,325 confirmed to be planets circling other stars. 21 of these are less that 2 Earth diameters which could be smaller rocky planets orbiting in their star’s habitable zone.
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- So we have a new planet to find in our own Solar System. We have new planets discovered in our nearest exo-solar system, our nearest star. And, we have thousands of new planets in other stars in our galaxy. Now, astronomers believe nearly every star has its own planets. We live in interesting times. So much to learn, so little time.
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