PLANETS
... star HD 209458 was shown to indicate the presence of a large exoplanet in transit across its surface from the perspective of Earth (1.7% dimming). Subsequent spectroscopic studies with the Hubble Space Telescope have even indicated that the exoplanet's atmosphere must have sodium vapor in it. The pl ...
... star HD 209458 was shown to indicate the presence of a large exoplanet in transit across its surface from the perspective of Earth (1.7% dimming). Subsequent spectroscopic studies with the Hubble Space Telescope have even indicated that the exoplanet's atmosphere must have sodium vapor in it. The pl ...
The Discovery of Planets beyond the Solar System
... There is a planet going around its star in only 3 days, there is another that takes 4.5 years. The planet closest to its star moves at only 0.04 of the Earth-Sun distance. The planet moving the farthest away is at 2.8 times the EarthSun distance from its star. In the Solar System, all planets move i ...
... There is a planet going around its star in only 3 days, there is another that takes 4.5 years. The planet closest to its star moves at only 0.04 of the Earth-Sun distance. The planet moving the farthest away is at 2.8 times the EarthSun distance from its star. In the Solar System, all planets move i ...
userfiles/602xxh/files/2013%e5%b1%8a%e9%ab%98%e4%b8%89
... most certain about are large—up to 25 times the size of Earth. According to Christophe Lovis, one of the scientists behind the finding, these five planets are similar to Neptune(海王星). “They’re made mainly of rocks and ice，” he said. “They’re probably not suitable for people to live in.” ...
... most certain about are large—up to 25 times the size of Earth. According to Christophe Lovis, one of the scientists behind the finding, these five planets are similar to Neptune(海王星). “They’re made mainly of rocks and ice，” he said. “They’re probably not suitable for people to live in.” ...
tremaine_stanford
... • how common are smaller planets (< 30 MEarth )? • how do giant planets form at semi-major axes 200 times smaller than any solar-system giant? • why are there no planets more massive than » 15 MJ? • what are the relative roles of Phase I and II evolution in determining the properties of extrasolar p ...
... • how common are smaller planets (< 30 MEarth )? • how do giant planets form at semi-major axes 200 times smaller than any solar-system giant? • why are there no planets more massive than » 15 MJ? • what are the relative roles of Phase I and II evolution in determining the properties of extrasolar p ...
the moons of jovian planets.
... b) the direction that planets orbit the Sun is opposite to the Sun’s spin. c) the terrestrial planets have higher density and lower mass. d) comets do not necessarily orbit in the plane of the solar system. Explanation: The planets do orbit in the same direction that the Sun spins. Most also spin in ...
... b) the direction that planets orbit the Sun is opposite to the Sun’s spin. c) the terrestrial planets have higher density and lower mass. d) comets do not necessarily orbit in the plane of the solar system. Explanation: The planets do orbit in the same direction that the Sun spins. Most also spin in ...
Possible climates on terrestrial exoplanets
... As discussed in Section 2.2., because atmospheric escape is closely related to the stellar activity, it is strongly time dependent at early ages. The timescale on which the various species can be added to the atmosphere is thus critical in determining what is left in the matured atmosphere. Hence, w ...
... As discussed in Section 2.2., because atmospheric escape is closely related to the stellar activity, it is strongly time dependent at early ages. The timescale on which the various species can be added to the atmosphere is thus critical in determining what is left in the matured atmosphere. Hence, w ...
pierrehumbert_lecture_1
... • Shorter wave ultraviolet drives photochemistry, and can break up heavy molecules into lighter components that escape more easily. • Low mass stars can take a half billion years to enter the main sequence, and UV/X-ray luminosity is further elevated throughout this time. • But as M stars age on the ...
... • Shorter wave ultraviolet drives photochemistry, and can break up heavy molecules into lighter components that escape more easily. • Low mass stars can take a half billion years to enter the main sequence, and UV/X-ray luminosity is further elevated throughout this time. • But as M stars age on the ...
lec01_26sep2011
... heat, the solar atmosphere originally extended beyond the orbits of all the planets and that it progressively shrank to its present limits. This might have occurred through causes similar to those which made the famous star of 1572 suddenly shine so brightly for several months in the constellation o ...
... heat, the solar atmosphere originally extended beyond the orbits of all the planets and that it progressively shrank to its present limits. This might have occurred through causes similar to those which made the famous star of 1572 suddenly shine so brightly for several months in the constellation o ...
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.