Earth is the third planet from the Sun and the only astronomical object known to harbor life. About 29% of Earth's surface is land consisting of continents and islands. The remaining 71% is covered with water, mostly by oceans but also lakes, rivers and other fresh water, which together constitute the hydrosphere. The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's outer layer is divided into several rigid tectonic plates that migrate across the surface over many millions of years. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates Earth's magnetic field, and a convecting mantle that drives plate tectonics.
Introduction
Earth
Earth | Introduction
It is the third planet from the Sun and the only astronomical object known to harbor life. : Earth is the third planet from the Sun and the only astronomical object known to harbor life. Earth is the third planet from the Sun and the only astronomical object known to harbor life. Earth is the third planet from the Sun and the only astronomical object known to harbor life.
what factor limits the number of eclipses each year
user
The alignment of the Sun, Moon and Earth.
assistant
what is this phenomena ?
user
A solar eclipse occurs when a portion of the Earth is engulfed in a shadow cast by the Moon which fully or partially blocks sunlight.
assistant
what are the different types of it ?
user
There are four types of solar eclipses.
assistant
what is their frequency ?
user
Between two and five solar eclipses occur every year.
assistant
what is their duration ?
user
The longest eclipse that has been calculated thus far is 7 minutes 29 seconds.
assistant
does it follow any path ?
user
Yes, the Moon's umbra moves rapidly from west to east across the Earth.
assistant
talk about the planet you mentioned above ?
user
However, does not belong to these. Instead, it follows a so-called horseshoe orbit along the path of the Earth.
2002 AA29 | Introduction
Earth is a planet in the Solar System, and the third planet from the Sun. Earth may also refer to:
Earth (disambiguation) | Introduction
Planet Earth is the third planet from the Sun. Planet Earth may also refer to:
Planet Earth (disambiguation) | Introduction
During a central eclipse, the Moon's umbra (or antumbra, in the case of an annular eclipse) moves rapidly from west to east across the Earth. The Earth is also rotating from west to east, at about 28 km/min at the Equator, but as the Moon is moving in the same direction as the Earth's rotation at about 61 km/min, the umbra almost always appears to move in a roughly west–east direction across a map of the Earth at the speed of the Moon's orbital velocity minus the Earth's rotational velocity. Rare exceptions can occur in polar regions where the path may go over or near the pole, as in 2021 on June 10 and December 4.
Solar eclipse | Path
All celestial bodies, the sun and the moon, the planets and stars, are attached to it and on it chart a regular east to west path.
Hedu kä misi | Introduction
says, 'I once took the moon to be (or saw the moon as) a planet, but I was mistaken.' Copernicus obliquely refers to Earth as a planet in "De Revolutionibus" when he says, "Having thus assumed the motions which I ascribe to the Earth later on in the volume, by long and intense study I finally found that if the motions of the other planets are correlated with the orbiting of the earth..." Galileo also asserts that Earth is a planet in the "Dialogue Concerning the Two Chief World Systems": "[T]he Earth, no less than the moon or any other planet, is to be numbered among the natural bodies that move circularly."
Definition of planet | Earth
He explains to his grandson that because the planets are set apart at fixed intervals, a sound is produced as they move. The moon, being the lowest sphere and the one closest to Earth, emits the lowest sound of all, whereas the heaven emits the highest. The Earth, on the other hand, does not move, remaining motionless at the center of the universe. Then the climatic belts of the earth are observed, from the snow fields to the deserts, and there is discussion of the nature of the Divine, the soul and virtue, from the Stoic point of view.
Somnium Scipionis | Contents
(2014) speculated that the planet may lie outside the habitable zone and closer to a Venus-like world.
Tau Ceti e | Introduction
The following outline is provided as an overview of and topical guide to the planet Earth: Earth – third planet from the Sun, the densest planet in the Solar System, the largest of the Solar System's four terrestrial planets, and the only astronomical object known to harbor life.
Outline of Earth | Introduction
Earth is the third planet from the Sun with an approximate distance of , and is traveling nearly through outer space.
Location of Earth | Details
Despite being officially classified as a near-Earth object, has a MOID (minimum orbit intersection distance) with Earth of ~0.067 AU, making it highly unlikely to ever hit Earth. For comparison, the Moon orbits Earth at about 1/26th this distance.
2013 JX28 | Introduction
The orbit of is extremely eccentric, going from the orbit of planet Mercury out into the asteroid belt, located between Mars and Jupiter.
2017 QP1 | Introduction
Earth's orbital speed averages 29.78 km/s (107,208 km/h; 66,616 mph), which is fast enough to cover the planet's diameter in 7 minutes and the distance to the Moon in 4 hours. From a vantage point above the north pole of either the Sun or Earth, Earth would appear to revolve in a counterclockwise direction around the Sun. From the same vantage point, both the Earth and the Sun would appear to rotate also in a counterclockwise direction about their respective axes.
Earth's orbit | Introduction
Consequently, "its atmosphere was ripped away from the planet by the solar wind. If you could stand on Mars today, you would find a landscape of lifeless desolation; very cold, and very dry."
A Beautiful Planet | Spaceship Earth
Everything below the moon is mutable and subject to the influences of the spheres. While the other planets have Intelligences (deities) associated with them, the Earth was not believed to have one since she did not move and so did not require guidance. Dante was the first to suggest an Intelligence for her: Fortune. "Fortune, to be sure does not steer the Earth through an orbit; she fulfills the office of an Intelligence in the mode proper for a stationary globe." Despite popular modern conception, the people of the Middle Ages were quite aware that the Earth was spherical. Lewis believes that the misconception may arise from the "mappemounde", which represent the Earth as a circle or disc.
The Discarded Image | The Earth
The Earth is a ball in space perpetually intercepting a cylinder of parallel energy rays from the sun. (Think of a tennis ball being held in the wind.) The angle of any earthly site to the solar beam is determined by The change due to date is the most difficult to visualize. The Earth’s axis is steady but "tilted": the plane that includes the Earth’s equator, which is perpendicular to the axis, is not parallel to the plane that includes the center of the sun and the center of the Earth, called the ecliptic. Think of the Earth as a car on a Ferris wheel.
Heliodon | Scientific background
Planets like this in that system have been presumed "super-Earth". However planets b, c, and d are presumed to have migrated in from outer orbits; and planet b is predicted a sub-Neptune. It is likely that this planet formed even further out. Whether it is a sub-Neptune, a super-Venus or even a super-Mercury is unknown.
HD 40307 e | Introduction
The Solar System, showing the Sun and the planets in the order of their position from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. (Pluto has since been reclassified as a dwarf planet by the International Astronomical Union, but it was considered a planet at the time the message was transmitted.) The Earth is the third planet from the Sun; its graphic is shifted up to identify it as the planet from which the signal was sent. Additionally, the human figure is shown just above the Earth graphic. In addition to showing position, the graphic provides a general, not-to-scale size reference of each planet and the Sun.
Arecibo message | Planets
When viewed from the north celestial pole (i.e., from the approximate direction of the star Polaris) the Moon orbits Earth anticlockwise and Earth orbits the Sun anticlockwise, and the Moon and Earth rotate on their own axes anticlockwise. The right-hand rule can be used to indicate the direction of the angular velocity. If the thumb of the right hand points to the north celestial pole, its fingers curl in the direction that the Moon orbits Earth, Earth orbits the Sun, and the Moon and Earth rotate on their own axes. In representations of the Solar System, it is common to draw the trajectory of Earth from the point of view of the Sun, and the trajectory of the Moon from the point of view of Earth.
Orbit of the Moon | Path of Earth and Moon around Sun
Earth orbits the Sun at an average distance of 149.60 million km (92.96 million mi), and one complete orbit takes days (1 sidereal year), during which time Earth has traveled 940 million km (584 million mi). Ignoring the influence of other solar system bodies, Earth's orbit is an ellipse with the Earth-Sun barycenter as one focus and a current eccentricity of 0.0167; since this value is close to zero, the center of the orbit is close, relative to the size of the orbit, to the center of the Sun. As seen from Earth, the planet's orbital prograde motion makes the Sun appear to move with respect to other stars at a rate of about 1° eastward per solar day (or a Sun or Moon diameter every 12 hours).
Earth's orbit | Introduction
Planets like this in that system have been presumed "super-Earth".
HD 40307 f | Introduction
They then plot the Spacer worlds on the ship's map, which form a rough sphere and conclude that the location of Earth must be near to the center of the sphere. This area turns out to have a binary star system.
Foundation and Earth | Part V: Melpomenia
Each planet's orbit is delineated by a set of elements:
Planet | Orbit
Earth's gravity interacts with other objects in space, especially the Sun and the Moon, which is Earth's only natural satellite. Earth orbits around the Sun in about 365.25 days. Earth's axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth. The gravitational interaction between Earth and the Moon causes tides, stabilizes Earth's orientation on its axis, and gradually slows its rotation. Earth is the densest planet in the Solar System and the largest and most massive of the four rocky planets. According to radiometric dating estimation and other evidence, Earth formed over 4.5 billion years ago.
Earth | Introduction
This planet is at a pre-modern, even barbaric stage of civilization, but may here and there have remarkable technologies that hint at a more advanced past. There is no obligation for the physical properties or biology of the alien planet to follow any scientific understanding of the potential conditions of habitable worlds; in general, the conditions will be earth-like, but with variations such as a different-colored sun or different numbers of moons. A lower gravity may be invoked to explain such things as large flying animals or people, or the superhuman strength of the hero, but will otherwise be ignored.
Sword and planet | Form
[Also,] how does the Earth get started up again, rotating at approximately the same rate of spin? The Earth cannot do it by itself, because of the law of the conservation of angular momentum."
Nibiru cataclysm | Scientific rejection
No planet's orbit is perfectly circular, and hence the distance of each varies over the course of its year. The closest approach to its star is called its periastron (perihelion in the Solar System), whereas its farthest separation from the star is called its apastron (aphelion). As a planet approaches periastron, its speed increases as it trades gravitational potential energy for kinetic energy, just as a falling object on Earth accelerates as it falls; as the planet reaches apastron, its speed decreases, just as an object thrown upwards on Earth slows down as it reaches the apex of its trajectory.
Planet | Orbit
The Earth is rotating or spinning around its axis. This is evidenced by day and night, at the equator the earth has an eastward velocity of . The Earth is also orbiting around the Sun in an orbital revolution. A complete orbit around the sun takes one year, or about 365 days; it averages a speed of about .
Motion | Earth
Without this tilt, there would be an eclipse every two weeks, alternating between lunar eclipses and solar eclipses. The Hill sphere, or the sphere of gravitational influence, of Earth is about in radius. This is the maximum distance at which Earth's gravitational influence is stronger than the more distant Sun and planets. Objects must orbit Earth within this radius, or they can become unbound by the gravitational perturbation of the Sun.
Earth | Orbit
The models of the Solar System, in order:
Sagan Planet Walk | Model gallery
This planet was typical as it was discovered spectroscopically using the radial velocity method.
HD 167042 b | Introduction
This could give the impression that the Moon orbits Earth in such a way that sometimes it goes backwards when viewed from the Sun's perspective. However, because the orbital velocity of the Moon around Earth (1 km/s) is small compared to the orbital velocity of Earth about the Sun (30 km/s), this never happens. There are no rearward loops in the Moon's solar orbit.
Orbit of the Moon | Path of Earth and Moon around Sun
An alternate version of Earth is the planet NowWhat, which occupies the same space as Earth, but not the same probability. In the 2005 film adaptation, a new Earth replaces the old one, and everything is restored to the moments leading up to its destruction, except for one thing: Arthur Dent is not part of the planet anymore, at his own request.
Earth in science fiction | "Hitchhiker's Guide"
If the Moon's rotation were purely synchronous, Earth would not have any noticeable movement in the Moon's sky. However, due to the Moon's libration, Earth does perform a slow and complex wobbling movement. Once a month, as seen from the Moon, Earth traces out an approximate oval 18° in diameter. The exact shape and orientation of this oval depend on one's location on the Moon. As a result, near the boundary of the near and far sides of the Moon, Earth is sometimes below the horizon and sometimes above it.
Earth phase | Overview
A more detailed explanation is best considered in terms of the paths of the Sun and Moon on the celestial sphere, as shown in the first diagram. This shows the abstract sphere surrounding the Earth at the center. The Earth is oriented so that its axis is vertical. The Sun is, by definition, always seen on the ecliptic (the Sun's apparent path across the sky) while Earth is tilted at an angle of "e" = 23.5° to the plane of that path and completes one orbit around the Sun in 365.25636 days, slightly longer than one year due to precession altering the direction of Earth's inclination.
Lunar standstill | Detailed explanation
After their wedding in Las Vegas, Susan finds herself wildly satisfied by Harold, even though men from his planet have no genitals and he has been equipped for his Earth visit with a penis that makes a loud whirring sound whenever he gets an erection.
What Planet Are You From? | Plot
Earth is the third planet from the Sun and the only astronomical object known to harbor life. About 29% of Earth's surface is land consisting of continents and islands. The remaining 71% is covered with water, mostly by oceans but also lakes, rivers and other fresh water, which together constitute the hydrosphere. The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's outer layer is divided into several rigid tectonic plates that migrate across the surface over many millions of years. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates Earth's magnetic field, and a convecting mantle that drives plate tectonics.
Earth | Introduction
The planet is probably very similar to the other hot Jupiters orbiting nearby stars. Its mass is about half that of Jupiter and it orbits the star at a distance less than 1/20th that of Earth from the Sun.
OGLE-TR-111b | Introduction
The orbits of planets around the Sun do not really follow an identical ellipse each time, but actually trace out a flower-petal shape because the major axis of each planet's elliptical orbit also precesses within its orbital plane, partly in response to perturbations in the form of the changing gravitational forces exerted by other planets. This is called perihelion precession or apsidal precession. In the adjunct image, Earth's apsidal precession is illustrated. As the Earth travels around the Sun, its elliptical orbit rotates gradually over time. The eccentricity of its ellipse and the precession rate of its orbit are exaggerated for visualization.
Precession | Apsidal precession
The text treats earth as a stationary globe around which sun, moon and five planets orbit. It makes no mention of Uranus, Neptune and Pluto. It presents mathematical formulae to calculate the orbits, diameters, predict their future locations and cautions that the minor corrections are necessary over time to the formulae for the various astronomical bodies. However, unlike the heliocentric model for the solar system, the "Surya Siddhanta" relies on an incorrect geocentric model. The text describes some of its formulae with the use of very large numbers for ""divya-yuga"", stating that at the end of this "yuga", Earth and all astronomical bodies return to the same starting point and the cycle of existence repeats again.
Surya Siddhanta | Planets and their characteristics
This is much older than any other known planet, and nearly three times as old as Earth. It has been undergoing many stages through its lifetime.
PSR B1620−26 b | Mass, orbit, and age
Thereafter, the tidal action of the Sun will extract angular momentum from the system, causing the orbit of the Moon to decay and the Earth's rotation to accelerate. In about 65 billion years, it is estimated that the Moon may end up colliding with the Earth, due to the remaining energy of the Earth–Moon system being sapped by the remnant Sun, causing the Moon to slowly move inwards toward the Earth. On a time scale of 10 (10 quintillion) years the remaining planets in the Solar System will be ejected from the system by violent relaxation. If Earth is not destroyed by the expanding red giant Sun and the Earth is not ejected from the Solar System by violent relaxation, the ultimate fate of the planet will be that it collides with the black dwarf Sun due to the decay of its orbit via gravitational radiation, in 10 (Short Scale: 100 quintillion, Long Scale: 100 trillion) years.
Future of Earth | Post-red giant stage
Most astronomers of the Kerala school who followed him accepted his planetary model.
Planet | India
If so, the main body would be an ellipsoid measuring 85×80×75 km (52x49x46 mi), and the moon would orbit away, measuring 55×30×30 km (34x18x18 mi). The density of both would be 1.1 g/cm³.
61 Danaë | Introduction
When a dead star passes planet Earth, its magnetic pull dislodges the English town of Shrimpton-on-the-Sea and causes it to break away and become its own miniature globe in orbit around the Earth. The village is now an island, the only land, and the rest of the mini planet is water which can be circumnavigated in a day. Sail straight and you eventually find the town again. The sun rises and sets every few hours and the Earth can be seen as a new moon in the sky. Otherwise, life is as before. As panic sets in, the upper and lower classes of the village set about forming a new government.
Once in a New Moon | Plot
A is the lowest-mass planet yet discovered by any observational technique, with somewhat less than twice the mass of Earth's moon.
PSR B1257+12 | Introduction
The Earth and its Moon are one example of this configuration. Today, the Moon is tidally locked to the Earth; one of its revolutions around the Earth (currently about 29 days) is equal to one of its rotations about its axis, so it always shows one face to the Earth. The Moon will continue to recede from Earth, and Earth's spin will continue to slow gradually. Other examples are the Galilean moons of Jupiter (as well as many of Jupiter's smaller moons) and most of the larger moons of Saturn. A different scenario occurs when the moon is either revolving around the primary faster than the primary rotates, or is revolving in the direction opposite the planet's rotation.
Formation and evolution of the Solar System | Moon–ring systems
It is as likely to be a regular planet moving in an orbit nearly circular to the sun as a Comet moving in a very eccentric ellipsis. I have not yet seen any coma or tail to it."
Uranus | Discovery
The next planet is also described by a single word. That word is "Ugh!"
The Waitabits | Plot
The journey starts with the Moon and its formation from an impact with the infant Earth. Next stop is the outer Solar System and the amazing process by particles of dust grew into planets. The nearest star is the place where star formation is considered, followed by the Orion Nebula, where young stars are forming at a furious rate. The last stop in the nearby universe is the center of our galaxy, site of a black hole four million times the mass of the Sun. The second third of the book examines the remote universe. Andromeda is seen as it was before humans evolved on the plains of Africa, and galaxies are all seen over time spans that dwarf our existence.
How It Began | Summary
The Moon and Earth orbit a common barycenter every 27.32 days relative to the background stars. When combined with the Earth–Moon system's common orbit around the Sun, the period of the synodic month, from new moon to new moon, is 29.53 days. Viewed from the celestial north pole, the motion of Earth, the Moon, and their axial rotations are all counterclockwise. Viewed from a vantage point above the north poles of both the Sun and Earth, Earth orbits in a counterclockwise direction about the Sun. The orbital and axial planes are not precisely aligned: Earth's axis is tilted some 23.44 degrees from the perpendicular to the Earth–Sun plane (the ecliptic), and the Earth–Moon plane is tilted up to ±5.1 degrees against the Earth–Sun plane.
Earth | Orbit
The Earth-MOID is . Its orbit is well-determined for the next several hundred years.
4769 Castalia | General information
's orbit is very eccentric, with an aphelion beyond the orbit of Mars and a perihelion inside the orbit of Mercury. It has an orbital period of 360.29 days (0.99 years) and makes close approaches to Earth. But makes closer approaches to other inner planets, especially Mars. Its closest approach to a planet between 1950–2200 was to Mars, as it passed from Mars on 18 March 1964, and will pass from Mars on 12 October 2065.
(66063) 1998 RO1 | Interaction with Earth
They arrive at the planet Alpha, which orbits Alpha Centauri and is all ocean except for an island 250 km long and 65 km wide on which live a small group of humans. In a reference to the radioactive Earth of Asimov's novel "Pebble in the Sky", the restoration of Earth's soil was eventually abandoned in favour of resettling the population to "New Earth", which the First Galactic Empire had already been terraforming. The natives appear friendly, but secretly intend to kill the visitors with a microbiological agent, to prevent them from informing the rest of the galaxy of their existence.
Foundation and Earth | Part VI: Alpha
Around the same time, the naturalist also narrated "Planet Earth".
Are We Changing Planet Earth? | Introduction
The problem is that, for example, the Earth is not only gravitationally attracted by the Sun, which would result in a stable and easily predicted elliptical orbit, but also in varying degrees by the Moon, the other planets and any other object in the solar system. These forces cause perturbations to the orbit, which change over time and which cannot be exactly calculated. They can be approximated, but to do that in some manageable way requires advanced mathematics or very powerful computers. It is customary to develop them into periodic series which are a function of time, e.g. "a"+"bt"+"ct"+...×cos("p"+"qt"+"rt"+...) and so forth one for each planetary interaction.
VSOP (planets) | History
As a super massive planet with an orbital period of hundreds of days, this occurrence is quite uncommon.
HD 38801 b | Introduction
This will also open doors for us to explore planets far beyond ours.
Jani Hirvinen | Introduction
In George Gurdjieff's Fourth Way school of thought, Earth Level or Planet Level refers to the level of the "Law of Forty-eight" on the Ray of Creation, meaning that forty-eight laws govern it. It corresponds to the Gurdjieff hydrogen number 48 and the musical note "mi". Moon Level precedes it and All Planets Level follows it.
Earth Level | Introduction
Uranus is a planet in the Solar System. Uranus may also refer to:
Uranus (disambiguation) | Introduction
The planet's name in Latin, used academically and scientifically in the West during the Renaissance, is the same as that of Terra Mater, the Roman goddess, which translates to English as Mother Earth.
Earth in culture | Etymology
This is a list of circumnavigations of Earth. Sections are ordered by ascending date of completion.
List of circumnavigations | Introduction
On Plön's Planet Walk the solar system is mapped on a scale of 1:2,000,000,000, starting from a symbol of the sun on the landing stage on Market Bridge.
Plön | Planet Walk
It moves in its orbit at a speed of over 300 km/s and is considered to be a relativistic binary, which causes the apses of the orbit to change in a predictable way.
HD 93205 | Introduction
All other planetary bodies in the Solar System also appear to periodically switch direction as they cross Earth's sky. Though all stars and planets appear to move from east to west on a nightly basis in response to the rotation of Earth, the outer planets generally drift slowly eastward relative to the stars. Asteroids and Kuiper Belt objects (including Pluto) exhibit apparent retrogradation. This motion is normal for the planets, and so is considered direct motion. However, since Earth completes its orbit in a shorter period of time than the planets outside its orbit, it periodically overtakes them, like a faster car on a multi-lane highway.
Apparent retrograde motion | From Earth
The Moon is Earth's only natural satellite. Moon may also refer to:
Moon (disambiguation) | Introduction
The small meteorite grasped by an attraction of a planet and for a while become its moon, [it has been learnt by] "Science Alert".
DN160822 03 | Introduction
The film shows the earth from the view of an orbiting Martian spaceship, which did not land but used cameras to film earth society. It follows average (what it believes to be) earthlings and their civilization, by in effect showing a "day in the life" and how they live it. First, it shows one having dinner - a precisely regulated feeding (vehicle refueling from a gas pump), then how it must take its rest (pulling into a house's attached garage), because the next day will be a busy one. The next morning it shows a large number of earthlings (cars) out traveling on roads and highways.
What on Earth! (film) | Plot
Notes
Dead Planet | Introduction
Depending on composition the two planets may be around the same size, or HD 154345 b may be larger. This planet may also harbor a system of moons and rings.
HD 154345 b | Characteristics
Because of the movement of Earth around the Earth–Moon center of mass, the apparent path of the Sun wobbles slightly, with a period of about one month. Because of further perturbations by the other planets of the Solar System, the Earth–Moon barycenter wobbles slightly around a mean position in a complex fashion. The ecliptic is actually the apparent path of the Sun throughout the course of a year. Because Earth takes one year to orbit the Sun, the apparent position of the Sun takes one year to make a complete circuit of the ecliptic. With slightly more than 365 days in one year, the Sun moves a little less than 1° eastward every day.
Ecliptic | Sun's apparent motion
Theia (Θεία in Greek) or Orpheus (Ορφεύς) ) is a hypothesized ancient planet in the early Solar System that, according to the giant-impact hypothesis, collided with the early Earth around 4.5 billion years ago, with the resulting debris gathering to form the Moon. In addition to explaining Earth's large moon, the Theia hypothesis can also explain why Earth's core is larger than would be expected for a body its size; Theia's core and mantle mixed with Earth's. According to one version of the hypothesis, Theia was an Earth trojan about the size of Mars, with a diameter of about .
Theia (planet) | Introduction
In Weinbaum's Solar System, in accordance with the then-current near-collision hypothesis, the gas giants radiate heat, enough to warm their satellites to Earthlike temperatures, allowing for Earthlike environments on Io, Europa, Titan, and even Uranus. Mars is also sufficiently Earthlike to allow humans to walk its surface (with training in thin-air chambers) unprotected. The series includes the following ten titles, in publication order:
Planetary series | Introduction
Brown estimates it is likely a dwarf planet based on its presumed size, calculated from its absolute magnitude (H) and assumed albedo.
(144897) 2004 UX10 | Introduction
He does several other things, such as creating balls of light and making the moon come out.
Corner of the Earth | Introduction
Mars is also sufficiently Earthlike to allow humans to walk its surface (with training in thin-air chambers) unprotected.
Stanley G. Weinbaum | Planetary series
A model that only includes the Earth, the Moon, and the Sun is called a tellurion or tellurium, and one which only includes the Earth and the Moon is a lunarium. A jovilabe is a model of Jupiter and its moons. A planetarium will show the "orbital period" of each planet and the "rotation rate", as shown in the table above. A tellurion will show the Earth with the Moon revolving around the Sun. It will use the angle of "inclination of the equator" from the table above to show how it rotates around its own axis. It will show the Earth's Moon, rotating around the Earth.
Orrery | Explanation
The computer was so large that it was often mistaken for a planet, and that it was destroyed five minutes before the program was due to complete (after ten million years of running). It also mentions that humans are descended from the passengers of an ark full of unwanted middlemen (hairdressers, telephone sanitizers, advertising executives and the like), tricked into leaving their own planet behind by spurious tales of impending destruction invented by the rest of the planet's civilization (it is mentioned that the population was then wiped out by a disease contracted from a dirty telephone). The Earth was located in Galactic sector ZZ9 Plural Z Alpha.
Earth in science fiction | "Hitchhiker's Guide"
On a medium-sized, low-gravity planet with a very slow rotational period, the side that is farthest from the sun is always a very hard mixture of frozen carbon dioxide, rock hard ammonia, and solid water ice, and the side that is closest, a sea of turbulent liquids and icebergs. The planet rotates so slowly that the part that is half ice and half ocean is constantly beset with troubling weather conditions, ranging from blizzards to unanticipated ice melts and earthquakes. It takes centuries if not thousands of years for the wobbling of the planet on the ecliptic to melt certain parts of the planet.
Fossil (novel) | Plot summary
HD 113766 represents the most well understood system in a growing class of objects that should provide more clues to how rocky planets like the Earth formed.
HD 113766 | Introduction
He was, however, partial to his own favourite movement, Saturn.
The Planets | Background
Now this has the form of a myth, but really signifies a declination of the bodies moving in the heavens around the earth, and a great conflagration of things upon the earth, which recurs after long intervals.""
Timaeus (dialogue) | Introduction
The planets are very close to the ecliptic, whereas comets and Kuiper belt objects are frequently at significantly greater angles to it. As a result of the formation of the Solar System planets, and most other objects, orbit the Sun in the same direction that the Sun is rotating (counter-clockwise, as viewed from above Earth's north pole). There are exceptions, such as Halley's Comet. Most of the larger moons orbit their planets in this "prograde" direction (with Triton being the largest "retrograde" exception) and most larger objects rotate themselves in the same direction (with Venus being a notable "retrograde" exception).
Solar System | Structure and composition
Long-term numerical integrations show that its orbit is very stable on Gyr time-scales (1 Gyr = 1 billion years). As in the case of Eureka, calculations in both directions of time (4.5 Gyr into the past and 4.5 Gyr into the future) indicate that may be a primordial object, perhaps a survivor of the planetesimal population that formed in the terrestrial planets region early in the history of the Solar System.
(385250) 2001 DH47 | Origin
The great ellipse is special case of an earth section path.
Great ellipse | Introduction
The orbital parameters of the known planet does not preclude the existence of an Earth-mass planet with a dynamically-stable orbit in the habitable zone.
HD 87883 | Introduction
found this planet in 2002 by using the telescope in Anglo-Australian Observatory.
HD 196050 b | Introduction
Some attendant moons are now represented by tiny holes in the disks.
Sagan Planet Walk | Individual models
Earth's shadow (or Earth shadow) is the shadow that Earth itself casts through its atmosphere and into outer space, toward the antisolar point. During the twilight period (both early dusk and late dawn), the shadow's visible fringe – sometimes called the dark segment or twilight wedge – appears as a dark and diffuse band just above the horizon, most distinct when the sky is clear. Since Earth's diameter is 3.7 times the Moon's, the length of the planet's umbra is correspondingly 3.7 times that of the lunar umbra: roughly .
Earth's shadow | Introduction
The Earth phase, Terra phase, terrestrial phase, or phase of Earth is the shape of the directly sunlit portion of Earth as viewed from the Moon (or elsewhere extraterrestrially). From the Moon, the Earth phases gradually and cyclically change over the period of a synodic month (about 29.53 days), as the orbital positions of the Moon around Earth and of Earth around the Sun shift.
Earth phase | Introduction
As Soter noted in his article, "how are we to quantify the degree of roundness that distinguishes a planet? Does gravity dominate such a body if its shape deviates from a spheroid by 10 percent or by 1 percent? Nature provides no unoccupied gap between round and nonround shapes, so any boundary would be an arbitrary choice." Furthermore, the point at which an object's mass compresses it into an ellipsoid varies depending on the chemical makeup of the object. Objects made of ices, such as Enceladus and Miranda, assume that state more easily than those made of rock, such as Vesta and Pallas.
Definition of planet | Hydrostatic equilibrium
In the distant future a planet settled by humans was once all airless moon rock. Human terraforming has transformed the moon into a world of shallow oceans and islands which are the peaks for the former moon craters. A young girl, Jobe, is sent to Option, the island of learning on the planet, to decide who she must be. When one of the gigantic opaque plasma shields that surround and protect the planet is destroyed, Jobe realizes she must begin her quest that the moonstar has destined for her long ago.
Moonstar Odyssey | Plot
According to scientific consensus, the Earth formed in orbit around the Sun about 4.5 billion years ago by accretion from a protoplanetary disk, and has remained near its original orbit until the present.
Kolob | Birthplace for the Earth
A planet is an astronomical body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and – acconding to the International Astronomical Union but not all planetary scientists – has cleared its neighbouring region of planetesimals. The term "planet" is ancient, with ties to history, astrology, science, mythology, and religion. Apart from Earth itself, five planets in the Solar System are often visible to the naked eye. These were regarded by many early cultures as divine, or as emissaries of deities. As scientific knowledge advanced, human perception of the planets changed, incorporating a number of disparate objects.
Planet | Introduction
In this section, the heavenly spheres are given in order from outermost to innermost. The outermost sphere is that of the fixed stars, which remains perfectly stationary. Then follow those of Saturn, Jupiter, Mars, Earth, Venus and Mercury, which each revolve about the Sun from west to east with successively shorter periods of revolution, Saturn's being between 29 and 30 years, Jupiter's between 11 and 12, Mars's between 2 and 3, Earth's exactly one, Venus's between 8 and 9 months, and Mercury's between 2 and 3 months. The Moon's sphere, however, revolves around the Earth in a period of one month, and moves with it around the Sun like an epicycle.
Commentariolus | The order of the spheres
The table below lists Solar System bodies once considered to be planets.
Planet | Objects formerly considered "planets"
(Smaller planets will lose any atmosphere they gain through various escape mechanisms.)
Planet | Formation
Any attempt to clarify this differentiation was to be left until a later date. There had also been criticism of the proposed definition of double planet: at present the Moon is defined as a satellite of the Earth, but over time the Earth-Moon barycenter will drift outwards (see tidal acceleration) and could eventually become situated outside of both bodies. This development would then upgrade the Moon to planetary status at that time, according to the definition. The time taken for this to occur, however, would be billions of years, long after many astronomers expect the Sun to expand into a red giant and destroy both Earth and Moon.
IAU definition of planet | Criticism
After the screening, a panel of leading environmental experts answered questions from around the world from the Berrill Lecture Theatre at The Open University, England.
The Planet (film) | Introduction
The distance between the orbits of "b" and "c" is only 1.6 times the distance between the Earth and the Moon. The planets should appear prominently in each other's skies, in some cases appearing several times larger than the Moon appears from Earth. A year on the closest planet passes in only 1.5 Earth days, while the seventh planet's year passes in only 18.8 days. The planets pass so close to one another that gravitational interactions are significant, and their orbital periods are nearly resonant. In the time the innermost planet completes eight orbits, the second, third, and fourth planets complete five, three, and two.
TRAPPIST-1 | Planetary system