Printable version: Pluto demoted -- from 9th planet to just a dwarf
... "Pluto is still Pluto, and this decision is really a celebration of our increasing scientific understanding of the solar system," Richard Binzell, an MIT planetary astronomer and member of the astronomical union's committee that drafted the definition of planets, said in a phone interview from Prag ...
... "Pluto is still Pluto, and this decision is really a celebration of our increasing scientific understanding of the solar system," Richard Binzell, an MIT planetary astronomer and member of the astronomical union's committee that drafted the definition of planets, said in a phone interview from Prag ...
Extrasolar Planets - University of Maryland Astronomy
... towards a higher probability of planets in stellar systems with more heavy elements, but as we discussed earlier this could in part be because such stars have more spectral lines and thus discovery is easier. Our inability to detect Earth-mass planets around normal stars means that there is lingerin ...
... towards a higher probability of planets in stellar systems with more heavy elements, but as we discussed earlier this could in part be because such stars have more spectral lines and thus discovery is easier. Our inability to detect Earth-mass planets around normal stars means that there is lingerin ...
Habitability of planets around Red Dwarf Stars
... brighter than its ZAMS value, but the most massive dM stars would be no more than 6% brighter than at ZAMS (for detailed evolutionary models of stars in the mass range 0.08 to 0.25 M see Laughlin et al., 1997). Other factors being equal, the rise in our Sun’s luminosity with MS evolution should, ov ...
... brighter than its ZAMS value, but the most massive dM stars would be no more than 6% brighter than at ZAMS (for detailed evolutionary models of stars in the mass range 0.08 to 0.25 M see Laughlin et al., 1997). Other factors being equal, the rise in our Sun’s luminosity with MS evolution should, ov ...
Circumstellar habitable zone
In astronomy and astrobiology, the circumstellar habitable zone (CHZ), or simply the habitable zone, is the region around a star within which planetary-mass objects with sufficient atmospheric pressure can support liquid water at their surfaces. The bounds of the CHZ are calculated using the known requirements of Earth's biosphere, its position in the Solar System and the amount of radiant energy it receives from the Sun. Due to the importance of liquid water to life as it exists on Earth, the nature of the CHZ and the objects within is believed to be instrumental in determining the scope and distribution of Earth-like extraterrestrial life and intelligence.The habitable zone is also called the Goldilocks zone, a metaphor of the children's fairy tale of Goldilocks and the Three Bears, in which a little girl chooses from sets of three items, ignoring the ones that are too extreme (large or small, hot or cold, etc.), and settling on the one in the middle, which is ""just right"".Since the concept was first presented in 1953, stars have been confirmed to possess a CHZ planet, including some systems that consist of multiple CHZ planets. Most such planets, being super-Earths or gas giants, are more massive than Earth, because such planets are easier to detect. On November 4, 2013, astronomers reported, based on Kepler data, that there could be as many as 40 billion Earth-sized planets orbiting in the habitable zones of Sun-like stars and red dwarfs in the Milky Way. 11 billion of these may be orbiting Sun-like stars. The nearest such planet may be 12 light-years away, according to the scientists. The CHZ is also of particular interest to the emerging field of habitability of natural satellites, because planetary-mass moons in the CHZ might outnumber planets.In subsequent decades, the CHZ concept began to be challenged as a primary criterion for life. Since the discovery of evidence for extraterrestrial liquid water, substantial quantities of it are now believed to occur outside the circumstellar habitable zone. Sustained by other energy sources, such as tidal heating or radioactive decay or pressurized by other non-atmospheric means, the basic conditions for water-dependent life may be found even in interstellar space, on rogue planets, or their moons. In addition, other circumstellar zones, where non-water solvents favorable to hypothetical life based on alternative biochemistries could exist in liquid form at the surface, have been proposed.