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The Earth Similarity Index ( ESI) is a proposed characterization of how similar a planetary-mass object or natural satellite is to Earth. It was designed to be a scale from zero to one, with Earth having a value of one; this is meant to simplify planet comparisons from large databases. The scale has no quantitative meaning for habitability .
Teegarden’s Star is a low-mass red dwarf, with a mass of around 9 percent the mass of the Sun, and with a temperature of around 2,900 Kelvin (2,623 °C or 4,760 F). Due to the very low temperature and luminosity of Teegarden's Star, it was only discovered in 2003, since it has an apparent magnitude of only 15.1 (and an absolute magnitude of ...
Earth's inner core is the innermost geologic layer of the planet Earth. It is primarily a solid ball with a radius of about 1,220 km (760 mi), which is about 19% of Earth's radius [0.7% of volume] or 70% of the Moon 's radius. [ 32][ 33] The inner core was discovered in 1936 by Inge Lehmann and is generally composed primarily of iron and some ...
This is a list of exoplanets within the circumstellar habitable zone that are under 10 Earth masses and smaller than 2.5 Earth radii, and thus have a chance of being rocky. [3] [1] Note that inclusion on this list does not guarantee habitability, and in particular the larger planets are more unlikely to have a rocky composition. [4]
Earth mover's distance. In computer science, the earth mover's distance ( EMD) [1] is a measure of dissimilarity between two frequency distributions, densities, or measures, over a metric space D . Informally, if the distributions are interpreted as two different ways of piling up earth (dirt) over D, the EMD captures the minimum cost of ...
The Earth Similarity Index page maintained by Abel Méndez at the University of Puerto Rico at Arecibo, lists both a simplified and peer-reviewed formula for the Earth Similarity Index. The disparity over Venus between 0.44 to 0.78 is related to use of the simplified (0.78) or peer-reviewed (0.44) formula.
In the 1790s, William Smith hypothesized that if two layers of rock at widely differing locations contained similar fossils, then it was very plausible that the layers were the same age. [16] Smith's nephew and student, John Phillips, later calculated by such means that Earth was about 96 million years old. [17]
Earth is rounded into an ellipsoid with a circumference of about 40,000 km. It is the densest planet in the Solar System. Of the four rocky planets, it is the largest and most massive. Earth is about eight light-minutes away from the Sun and orbits it, taking a year (about 365.25 days) to complete one revolution.