The majority of Ben Collins American Museum Of Tort Law shirt in the Milky Way, around 80%, are red dwarfs, small stars between about half the size of our sun and 10% the size of our sun. That still leaves between 40–80 billion stars much like the sun. If one in five of those has an Earth-like planet, that means there may be between eight and sixteen billion Earth-like planets in the Milky Way. Of course these numbers may be off. The number of sun-like stars may be lower, or higher. The number of Earth-like planets may be more, or less. We just can’t know, so far. Further, there is no reason to assume that only stars like our sun will have planets capable of supporting life. Or that only a planet will support life. There may be intelligent life on a large moon of a gas giant exoplanet in the “Goldilocks zone” of a red dwarf. There is also no way to know how typical the Sol system is with it’s eight planets, half of which are ice or gas giants, and half of which are small rocky planets like Earth. Most of the exoplanets we know about are gas giants like Jupiter, just because they are easier to detect. Remember, we haven’t actually “seen” any exoplanets. We only know they are there by the way their gravity affects their home stars, causing a wobble, or they are aligned with Earth such that the transit of the planet between Earth and its star causes the star to flicker. Small, rocky planets like Earth are just harder to find. So there may be lots of them, or not. We just don’t know, yet.
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One advantage of the numerous distance-measuring schemes in use, which overlap over a range of Philadelphia Phillies baseball with Sunflower Leopard American flag shirt from nearby to very distant, is that astronomers can calibrate and corroborate their measurements with multiple approaches. Such calibrations and corroborations thus lend an additional measure of reliability to these schemes. Indeed, by comparing results using different methods, weaknesses have been identified in certain schemes. In most cases, additional studies have demonstrated ways to guard against and correct for known difficulties. As a single example of these multiple approaches, prior to 2011 the distance to the Pinwheel Galaxy was determined, based on measurements of Cepheid variable stars in the galaxy, to be 20.9 million light-years, with an uncertainty of 1.8 million light-years. As of September 2011, measurements of the light output of the 2011 Type Ia supernova in the Pinwheel Galaxy are completely consistent with this distance figure…. In short, distances to astronomical objects can be and have been measured with substantial accuracy and reliability. For the most part, the calculations involved employ only basic mathematics taught in high school. Thus the overall conclusion of a universe consisting of billions of galaxies, most of them many millions of light-years away, is beyond reasonable doubt at the present time..
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