The solar system probably formed about 4.5 billion years ago from a giant disk of gas, dust and ice in space. ... All forms of life on Earth require liquid water to survive, so the presence of liquid water is a good criterion for deciding whether other planets in the universe could be habitable. Earth is the only habitable planet in the solar system. Venus, closer to the Sun, is too hot to have liquid water. Planets and moons in the outer solar system are too cold for liquid water. ...

... 9a. Earth orbits Sun? . ... Kepler's Laws . ... and First Law . ... Such " polar coordinates " ( drawing on the left, below) are the ones best suited for describing planetary motion. ... All planetary orbits resemble ellipses, each with its own value of e or eccentricity : the smaller e is, the closer the shape to a circle. ... We can now state Kepler's law more precisely as "the square of the orbital period T is proportional to the cube of the semi-major axis a of its orbit around the Sun." ...

... Tonight's Sky . ... The Magazine . ... Star Atlas . ... An artificial comet holds secrets to Earths life . ... Astronomy for Kids . ... Observing springtime deep-sky objects with a large telescope . ... The planet has extreme temperature swings and perhaps active lava flows. ... A digital supplement to Astronomy magazine. ... Join TravelQuest International with Astronomy and Discover magazines on one of three great tour options surrounding this celestial spectacle . ... Astronomy Magazine . ...

In ancient times the solar system was thought to be the whole Universe, so the study of planetary motions was cosmology. ... The planets other than the Moon and Sun generally move West to East through the stars, but occasionally stop and move in the opposite direction ( retrograde motion). In order to explain the retrograde motion of the planets, the geocentric model of the Solar System shown above puts the planets on small circles called epicycles . ...

... More on 51 Peg: . The discovery of a Jupiter--mass planet in orbit around the solar--type star 51Peg has been reported by Michel Mayor and Didier Queloz (Geneva Observatory) on October 6th at the 9th Cambridge workshop on "cool stars, stellar systems, and the sun" held at Florence (Italy). ... Recall that the measurements of radial velocity only yield v sin i which in turn gives us M sin i. For most values of i, sin i will be greater than 0.5 and this gives a mass estimate of 0.5 Jupiter masses. ...

... малой планете . ... на основании решения от 9 мая 2001 года . Комитета по наименованию малых планет . ... что малая планета, . зарегистрированная в международном каталоге малых планет . под N 11438 и имеющая предварительное обозначение 1973 QR1, . ... ZELDOVICH . ... Якова Борисовича Зельдовича . ... 11438) Zeidovich = 1973 QR1 . ... Малая планета (11438) Zeidovich открыта 29 августа 1973 г. Т.M.Смирновой в Крымской астрофизической обсерватории. ... Циркуляр Малых Планет N 42672, 2001. ...

... Space Telescope Science Institute and Johns Hopkins University . A multidisciplinary course exploring the origins of life, planetary formation, Earth's evolution, extrasolar planets, habitable zones, life in extreme environments, the search for life in the Universe, and space missions. DiRuggiero, Norman, and others, 3 credit hours. ... The JHU Department of Earth and Planetary Sciences also offers courses that may be of interest to students interested in astrobiology: . ...

... There has been a heated public discussion in the past few years about whether our ninth planet is really deserving of the name. Since Pluto orbits a star, and is much less luminous, it certainly satisfies the definition we have above. The problem is actually not with Pluto, but with a very large number of other bodies in our Solar System which also satisfy this definition, but which are not called planets. Perhaps the most notable of these is Ceres, the largest asteroid. ... Planet . ...

... Bad Astronomy . ... Bitesize Astronomy . ... The Nine Planets . ... It isn't the first extrasolar planetary system to be discovered; the first planet outside our own solar system orbiting a normal Sunlike star was discovered in 1995. ... Still, this is the first solar system ever found besides our own to definitely have more than one planet. This is an important discovery: most people all along have been assuming that multiple planet systems exist, but we had never actually seen one. ...

... Planets In The Sun . ... Credit: SOHO - LASCO Consortium, ESA , NASA Explanation: Today , all five naked-eye planets (Mercury, Venus, Mars, Jupiter, Saturn) plus the Moon and the Sun will at least approximately line-up. ... The horizontal bars through the planets are digital image artifacts. ... Publications with keywords: Jupiter - Mars - planet - Saturn - Sun - planetary alignment - Moon . Publications with words: Jupiter - Mars - planet - Saturn - Sun - planetary alignment - Moon . ...

... AMPLE (Adaptable Minor Planet Ephemerides) is integrated software package to deal with a number of problems concerning minor planets with the aid of IBM-type personal computer. ... compiling a list of all numbered minor planets which can be seen at certain moment within specified sky region and visualization of their mutual positions; . ... As AMPLE is able to reproduce virtually any table of "the Ephemerides of Minor Planets" , it may be considered as computer version of the EMP. ...

... Planets . ... Earth Satellites . ... The newly discovered ?mega-Earth? ... Its sibling, the lava world Kepler-10b, is in the background (the two planets? proximity is grossly exaggerated) .€а Kepler-10c has a diameter of about 29 000 km, 2.3 times as large as Earth, and weighs 17 times as much. ... The first mega-earth to be discovered is Kepler-10c which orbits a star lying about 560 light years from the Sun in the constellation Draco. ... Astronomers Find a New Type of Planet: The ?Mega-Earth? ...

Astronomy Discussion Forums . Forums: . ... Discussion Forums . ... Gravity Of Planets Mass . Forum List | ... Post Message | ... Login to Post . ... www.astronomy.net . About Astronomy Net | Advertise on Astronomy Net | ... Unless otherwise specified, web site content Copyright 1994-2016 John Huggins All Rights Reserved . Forum posts are Copyright their authors as specified in the heading above the post. "dbHTML," "AstroGuide," "ASTRONOMY.NET" & "VA.NET" . ...

Computer Ephemeris. Ephemeris for physical observations of the planets. Explanations. Each row of the table contains for date specified at 0h of Time Terrestrial Dynamical: . ... position angle of axis of planetary rotation (degrees) - 'P', . ... illumanated part of the disk - k, . ... position angle of disk point with minimal illumination (degrees), . longitude of central meridian of the disk (degrees) - 'merid1' - system I and so... phase correction (degrees). ...

... This form allows you to query a database containing planetary data. Simply select the fields for the information desired. Select type of data to use: . Sun, Planets & Satellites Planets Only Satellites Only . ... Radius Mass Density Orbital Period Inclination . Tilt of Axis Eccentricity Escape Velocity Rotational Period . Albedo Mean Orbital Velocity Discoverer . ... Select the information to be included: . ... Rotational Period Albedo Mean Orbital Velocity Discoverer . ...

... 2008 November 17 . HR 8799: Discovery of a Multi-planet Star System . ... Explanation: How common are planetary systems like our own Solar System? In the twelve years previous to 2008, over 300 candidate planetary systems have been found orbiting nearby stars. ... Although the HR 8799 planetary system has significant differences with our Solar System, it is a clear demonstration that complex planetary systems exist, systems that could conceivable contain an Earth-like planet . ... About APOD | ...

... 3 Seasons of the year and inclination of the Earth's axis. ... 6 Calendar: solar and sidereal day . ... 9 Retrograde motion of inner and outer planets. ... Center of motion is not Sun but mutual center of gravity. 12a Concept of solving an equation by iteration [see M-2 for "Algorithm"] . ... 17 Concept of mass--gravitational vs. inertia. ... 25 Concept of center of gravity . Principle of rocket motion. ... 8 Size of Earth as estimated by the ancients and by Columbus. 8a The story of Pike's Peak. ...

delay-doppler image of the Maxwell Montes region of Venus, taken using the S-Band (2380 MHz or 12.6 cm) radar transmitter and the 305m dish at the Arecibo Observatory in Arecibo, Puerto Rico in June of 1988. The horizontal resolution is about 2 km. ... This delay-doppler radar image shows craters near the North pole of Mercury. The resolution of this image is about 15 km. ...

... galaxies: bulges galaxies: clusters: general galaxies: clusters: individual: . ... star formation statistics stellar content structure Cosmology ( cosmology :) cosmic background radiation ( cosmology :) cosmological parameters cosmology : miscellaneous cosmology : observations cosmology : theory ( cosmology :) dark ages, reionization, first stars ( cosmology :) dark energy ( cosmology :) dark matter ( cosmology :) diffuse radiation ( cosmology :) distance scale ( cosmology :) early Universe (...

... CONTACT . ... Planned space experiments promise a considerable increase in the detections and statistical knowledge arising especially from transit and astrometric measurements over the years 2005­15, with some hundreds of terrestrial-type planets expected from transit measurements, and many thousands of Jupiter-mass planets expected from astrometric measurements. ... To request a printed copy, please contact Britt Sjoeberg (bsjoeber@eso.org) . ...