vania-janet/multiturn-rag-retrieval-data huggingface dataset:
Lunar phase
In Western culture , the four principal lunar phases are new moon , first quarter , full moon , and third quarter ( also known as last quarter ) . These are the instances when the Moon 's apparent geocentric celestial longitude minus the Sun 's apparent geocentric celestial longitude is 0 ° , 90 ° , 180 ° and 270 ° , respectively . Each of these phases occur at slightly different times when viewed from different points on the Earth . During the intervals between principal phases , the Moon appears either crescent - shaped or gibbous . These shapes , and the periods of time when the Moon shows them , are called the intermediate phases . They last , on average , one - quarter of a synodic month , roughly 7.38 days , but their durations vary slightly because the Moon 's orbit is slightly elliptical , and thus its speed in orbit is not constant . The descriptor waxing is used for an intermediate phase when the Moon 's apparent size is increasing , from new moon toward full moon , and waning when the size is decreasing .
Lunar eclipse
A penumbral eclipse occurs when the moon passes through the Earth 's penumbra . The penumbra causes a subtle darkening of the moon 's surface . A special type of penumbral eclipse is a total penumbral eclipse , during which the Moon lies exclusively within the Earth 's penumbra . Total penumbral eclipses are rare , and when these occur , that portion of the moon which is closest to the umbra can appear somewhat darker than the rest of the moon .
Magnetosphere of Jupiter
Charged particles have a considerable influence on the surface properties of Galilean moons . Plasma originating from Io carries sulfur and sodium ions farther from the planet , where they are implanted preferentially on the trailing hemispheres of Europa and Ganymede . On Callisto however , for unknown reasons , sulfur is concentrated on the leading hemisphere . Plasma may also be responsible for darkening the moons ' trailing hemispheres ( again , except Callisto 's ) . Energetic electrons and ions , with the flux of the latter being more isotropic , bombard surface ice , sputtering atoms and molecules off and causing radiolysis of water and other chemical compounds . The energetic particles break water into oxygen and hydrogen , maintaining the thin oxygen atmospheres of the icy moons ( since the hydrogen escapes more rapidly ) . The compounds produced radiolytically on the surfaces of Galilean moons also include ozone and hydrogen peroxide . If organics or carbonates are present , carbon dioxide , methanol and carbonic acid can be produced as well . In the presence of sulfur , likely products include sulfur dioxide , hydrogen disulfide and sulfuric acid . Oxidants produced by radiolysis , like oxygen and ozone , may be trapped inside the ice and carried downward to the oceans over geologic time intervals , thus serving as a possible energy source for life .
Lunar distance (astronomy)
Taking pictures of the Moon before it enters into the penumbra and after it is completely eclipsed . Measuring , as precise as possible , the time of the eclipse contacts . Taking good pictures of the partial eclipse when the shape and size of the Earth shadow is clearly visible . Taking a picture of the Moon including in the same field of view , Spica and Mars - from various locations .
Lunar phase
In the Southern Hemisphere the Moon is observed from a perspective inverted to that of the northern hemisphere , and all of the images in this article , so that the opposite sides appear to grow ( wax ) and shrink ( wane ) .
Magnetosphere of Jupiter
Jupiter 's extensive magnetosphere envelops its ring system and the orbits of all four Galilean satellites . Orbiting near the magnetic equator , these bodies serve as sources and sinks of magnetospheric plasma , while energetic particles from the magnetosphere alter their surfaces . The particles sputter off material from the surfaces and create chemical changes via radiolysis . The plasma 's co-rotation with the planet means that the plasma preferably interacts with the moons ' trailing hemispheres , causing noticeable hemispheric asymmetries . In addition , the large internal magnetic fields of the moons contribute to the Jovian magnetic field . Jupiter
Rainbow
Like most atmospheric optical phenomena , rainbows can be caused by light from the Sun , but also from the Moon . In case of the latter , the rainbow is referred to as a lunar rainbow or moonbow . They are much dimmer and rarer than solar rainbows , requiring the Moon to be near - full in order for them to be seen . For the same reason , moonbows are often perceived as white and may be thought of as monochrome . The full spectrum is present , however , but the human eye is not normally sensitive enough to see the colours . Long exposure photographs will sometimes show the colour in this type of rainbow .
Lunar eclipse
There is often confusion between a solar and lunar eclipse . While both involve interactions between the sun , Earth , and moon , they are very different in their interactions .
Lunar phase
When the Sun and Moon are aligned on the same side of the Earth , the moon is `` new '' , and the side of the Moon facing Earth is not illuminated by the Sun . As the moon waxes ( the amount of illuminated surface as seen from Earth is increasing ) , the lunar phases progress through new moon , crescent moon , first - quarter moon , gibbous moon , and full moon . The moon is then said to wane as it passes through the gibbous moon , third - quarter moon , crescent moon and back to new moon . The terms `` old moon '' and `` new moon '' are not interchangeable . The `` old moon '' is a waning sliver ( which eventually becomes undetectable to the naked eye ) until the moment it aligns with the sun and begins to wax , at which point it becomes new again . Half moon is often used to mean the first - and third - quarter moons , while the term ' quarter ' refers to the extent of the moon 's cycle around the Earth , not its shape .
Earth
The Moon may have dramatically affected the development of life by moderating the planet 's climate . Paleontological evidence and computer simulations show that Earth 's axial tilt is stabilized by tidal interactions with the Moon . Some theorists think that without this stabilization against the torques applied by the Sun and planets to Earth 's equatorial bulge , the rotational axis might be chaotically unstable , exhibiting chaotic changes over millions of years , as appears to be the case for Mars .
Lunar distance (astronomy)
Early attempts to measure the distance to the Moon exploited observations of a lunar eclipse combined with knowledge of Earth 's radius and an understanding that the Sun is much further than the Moon . By observing the geometry of a lunar eclipse , the lunar distance can be calculated using trigonometry .
Rainbow
It has been suggested that rainbows might exist on Saturn 's moon Titan , as it has a wet surface and humid clouds . The radius of a Titan rainbow would be about 49 ° instead of 42 ° , because the fluid in that cold environment is methane instead of water . Although visible rainbows may be rare due to Titan 's hazy skies , infrared rainbows may be more common , but an observer would need infrared night vision goggles to see them .
Lunar distance (astronomy)
The giant impact hypothesis , a widely accepted theory , states that the Moon was created as a result of a catastrophic impact between another planet and Earth , resulting in a re-accumulation of fragments at an initial distance of 3.8 R. In this theory , the initial impact is assumed to have occurred 4.5 billion years ago .
Sundial
The surface receiving the shadow need not be a plane , but can have any shape , provided that the sundial maker is willing to mark the hour - lines . If the style is aligned with the Earth 's rotational axis , a spherical shape is convenient since the hour - lines are equally spaced , as they are on the equatorial dial above ; the sundial is equiangular . This is the principle behind the armillary sphere and the equatorial bow sundial . However , some equiangular sundials -- such as the Lambert dial described below -- are based on other principles .
Lunar phase
Nearer the Equator the Moon with its terminator will appear apparently horizontal during the morning and evening . Since the above descriptions of the lunar phases only apply at temperate or high latitudes and observers moving towards the Tropics from northern or southern latitudes will see the Moon rotated anti-clockwise or clockwise with respect to the images in this article . The crescent Moon can open upward or downward , with the `` horns '' of the crescent pointing up or down , respectively . When the Sun appears above the Moon in the sky , the crescent opens downward ; when the Moon is above the Sun , the crescent opens upward . The crescent Moon is most clearly and brightly visible when the Sun is below the horizon , which implies that the Moon must be above the Sun , and the crescent must open upward . This is therefore the orientation in which the crescent Moon is most often seen from the Earth 's tropics . The waxing and waning crescents look very similar . The waxing crescent appears in the western sky in the evening , and the waning crescent in the east , in the morning .
Hilda group
Each of the Hilda objects moves along its own elliptic orbit . However , at any moment the Hildas together constitute this triangular configuration , and all the orbits together form a predictable ring . Figure 2 illustrates this with the Hildas positions ( black ) against a background of their orbits ( gray ) . For the majority of these asteroids , their position in orbit may be arbitrary , except for the external parts of the apexes ( the objects near aphelion ) and the middles of the sides ( the objects near perihelion ) . The Hildas Triangle has proven to be dynamically stable over a long time span . Left
Wikipedia:Citing sources
The sun is pretty big , but the moon is not so big . The sun is also quite hot . Notes
Kuiper belt
Initially , detailed analysis of KBOs was impossible , and so astronomers were only able to determine the most basic facts about their makeup , primarily their color . These first data showed a broad range of colors among KBOs , ranging from neutral grey to deep red . This suggested that their surfaces were composed of a wide range of compounds , from dirty ices to hydrocarbons . This diversity was startling , as astronomers had expected KBOs to be uniformly dark , having lost most of the volatile ices from their surfaces to the effects of cosmic rays . Various solutions were suggested for this discrepancy , including resurfacing by impacts or outgassing . Jewitt and Luu 's spectral analysis of the known Kuiper belt objects in 2001 found that the variation in color was too extreme to be easily explained by random impacts . The radiation from the Sun is thought to have chemically altered methane on the surface of KBOs , producing products such as tholins . Makemake has been shown to possess a number of hydrocarbons derived from the radiation - processing of methane , including ethane , ethylene and acetylene .
Lunar eclipse
L = 0 : Very dark eclipse . Moon almost invisible , especially at mid-totality . L = 1 : Dark eclipse , gray or brownish in coloration . Details distinguishable only with difficulty . L = 2 : Deep red or rust - colored eclipse . Very dark central shadow , while outer edge of umbra is relatively bright . L = 3 : Brick - red eclipse . Umbral shadow usually has a bright or yellow rim . L = 4 : Very bright copper - red or orange eclipse . Umbral shadow is bluish and has a very bright rim .
Wikipedia:Citing sources
The Sun is pretty big , but the Moon is not so big . The Sun is also quite hot . Notes
Lunar eclipse
P1 ( First contact ) : Beginning of the penumbral eclipse . Earth 's penumbra touches the Moon 's outer limb . U1 ( Second contact ) : Beginning of the partial eclipse . Earth 's umbra touches the Moon 's outer limb . U2 ( Third contact ) : Beginning of the total eclipse . The Moon 's surface is entirely within Earth 's umbra . Greatest eclipse : The peak stage of the total eclipse . The Moon is at its closest to the center of Earth 's umbra . U3 ( Fourth contact ) : End of the total eclipse . The Moon 's outer limb exits Earth 's umbra . U4 ( Fifth contact ) : End of the partial eclipse . Earth 's umbra leaves the Moon 's surface . P4 ( Sixth contact ) : End of the penumbral eclipse . Earth 's penumbra no longer makes contact with the Moon .
Lunar distance (astronomy)
Until the late 1950s all measurements of lunar distance were based on optical angular measurements . The space age marked a turning point which greatly advanced the precision and accuracy of our knowledge of this value . During the 1950s and 1960s , experiments were conducted that utilized radar , lasers , spacecraft , and computer modeling .
Mars
With the presence of various orbiters , landers , and rovers , it is possible to practice astronomy from Mars . Although Mars 's moon Phobos appears about one - third the angular diameter of the full moon on Earth , Deimos appears more or less star - like , looking only slightly brighter than Venus does from Earth .
Lunar eclipse
Several cultures have myths related to lunar eclipses or allude to the lunar eclipse as being a good or bad omen . The Egyptians saw the eclipse as a sow swallowing the moon for a short time ; other cultures view the eclipse as the moon being swallowed by other animals , such as a jaguar in Mayan tradition , or a three legged toad in China . Some societies thought it was a demon swallowing the moon , and that they could chase it away by throwing stones and curses at it . The Greeks were ahead of their time when they said the Earth was round and used the shadow from the lunar eclipse as evidence . Some Hindus believe in the importance of bathing in the Ganges River following an eclipse because it will help to achieve salvation .
Mars
The dichotomy of Martian topography is striking : northern plains flattened by lava flows contrast with the southern highlands , pitted and cratered by ancient impacts . Research in 2008 has presented evidence regarding a theory proposed in 1980 postulating that , four billion years ago , the northern hemisphere of Mars was struck by an object one - tenth to two - thirds the size of Earth 's Moon . If validated , this would make the northern hemisphere of Mars the site of an impact crater 10,600 by 8,500 km ( 6,600 by 5,300 mi ) in size , or roughly the area of Europe , Asia , and Australia combined , surpassing the South Pole -- Aitken basin as the largest impact crater in the Solar System . Fresh
Moon landing
Advances in US nuclear weapon technology had led to smaller , lighter warheads , and consequently , rockets with smaller payload capacities . By comparison , Soviet nuclear weapons were much heavier , and the powerful R - 7 rocket was developed to carry them . More modest potential missions such as flying around the Moon without landing or establishing a space lab in orbit ( both were proposed by Kennedy to von Braun ) were determined to offer too much advantage to the Soviets , since the US would have to develop a heavy rocket to match the Soviets . A Moon landing , however , would capture world imagination while functioning as propaganda . Apollo
Sundial
In some cases , the sundials are formed as hollows in a solid object , e.g. , a cylindrical hollow aligned with the Earth 's rotational axis ( in which the edges play the role of styles ) or a spherical hollow in the ancient tradition of the hemisphaerium or the antiboreum . ( See the History section above . ) In some cases , these multiface dials are small enough to sit on a desk , whereas in others , they are large stone monuments .
Moon landing
The final Pioneer lunar probe design consisted of four `` paddlewheel '' solar panels extending from a one - meter diameter spherical spin - stabilized spacecraft body that was equipped to take images of the lunar surface with a television - like system , estimate the Moon 's mass and topography of the poles , record the distribution and velocity of micrometeorites , study radiation , measure magnetic fields , detect low frequency electromagnetic waves in space and use a sophisticated integrated propulsion system for maneuvering and orbit insertion as well . None of the four spacecraft built in this series of probes survived launch on its Atlas ICBM outfitted with an Able upper stage .
The Book of the Thousand Nights and a Night
In 1982 , the International Astronomical Union ( IAU ) began naming features on Saturn 's moon Enceladus after characters and places in Burton 's translation because `` its surface is so strange and mysterious that it was given the Arabian Nights as a name bank , linking fantasy landscape with a literary fantasy '' . ( See List of geological features on Enceladus . )
Wonders of the Solar System
Cox starts this episode in Al - Qayrawan , Tunisia to analyse the orbit of the planets around our Sun , with details on how the 23 degree tilt of the Earth creates the seasonal weather patterns . He also visits the Atlas Mountains , and relates how in clear night skies the ancients observed the rotation of the stars and the retrograde and prograde motion of Mars and the other wandering planets . In Oklahoma , USA , he discusses the universal reach of the Coriolis effect and the importance of the conservation of angular momentum . Next , at the Jet Propulsion Laboratory he examines how the Cassini -- Huygens space - probe 's imagery provides an insight on the highly complex structure of the ice rings of Saturn , and its diverse array of moons , and how they can reveal insights into the formation and evolution of the solar system . He also explains how Enceladus , as the most reflective object in the known universe , has been of interest due to its continental divide - like canyons and geysers ( as also observed in parts of Iceland ) . In the Sahara Desert the formative effect of winds on sand - dune morphology is paralleled to that of the gravitational effect of Saturn 's 61 known moons on the matter that composite the rings - a phenomenon called orbital resonance .
Jupiter
The moons discovered by Galileo -- Io , Europa , Ganymede , and Callisto -- are among the largest satellites in the Solar System . The orbits of three of them ( Io , Europa , and Ganymede ) form a pattern known as a Laplace resonance ; for every four orbits that Io makes around Jupiter , Europa makes exactly two orbits and Ganymede makes exactly one . This resonance causes the gravitational effects of the three large moons to distort their orbits into elliptical shapes , because each moon receives an extra tug from its neighbors at the same point in every orbit it makes . The tidal force from Jupiter , on the other hand , works to circularize their orbits .
Lunar phase
It might be expected that once every month , when the Moon passes between Earth and the Sun during a new moon , its shadow would fall on Earth causing a solar eclipse , but this does not happen every month . Nor is it true that during every full moon , the Earth 's shadow falls on the Moon , causing a lunar eclipse . Solar and lunar eclipses are not observed every month because the plane of the Moon 's orbit around the Earth is tilted by about 5 ° with respect to the plane of Earth 's orbit around the Sun ( the plane of the ecliptic ) . Thus , when new and full moons occur , the Moon usually lies to the north or south of a direct line through the Earth and Sun . Although an eclipse can only occur when the Moon is either new ( solar ) or full ( lunar ) , it must also be positioned very near the intersection of Earth 's orbital plane about the Sun and the Moon 's orbital plane about the Earth ( that is , at one of its nodes ) . This happens about twice per year , and so there are between four and seven eclipses in a calendar year . Most of these eclipses are partial ; total eclipses of the Moon or Sun are less frequent .
Moon landing
This payload sphere contained six silver - cadmium batteries to power a fifty - milliwatt radio transmitter , a temperature sensitive voltage controlled oscillator to measure lunar surface temperatures , and a seismometer that was designed with sensitivity high enough to detect the impact of a 5 lb ( 2.3 kg ) meteorite on the opposite side of the Moon . Weight was distributed in the payload sphere so it would rotate in its liquid blanket to place the seismometer into an upright and operational position no matter what the final resting orientation of the external landing sphere . After landing , plugs were to be opened allowing the freon to evaporate and the payload sphere to settle into upright contact with the landing sphere . The batteries were sized to allow up to three months of operation for the payload sphere . Various mission constraints limited the landing site to Oceanus Procellarum on the lunar equator , which the lander ideally would reach 66 hours after launch .
Sundial
This conic section is the intersection of the cone of light rays with the flat surface . This cone and its conic section change with the seasons , as the Sun 's declination changes ; hence , sundials that follow the motion of such light - spots or shadow - tips often have different hour - lines for different times of the year . This is seen in shepherd 's dials , sundial rings , and vertical gnomons such as obelisks . Alternatively , sundials may change the angle or position ( or both ) of the gnomon relative to the hour lines , as in the analemmatic dial or the Lambert dial .
Lunar eclipse
A lunar eclipse occurs when the Moon passes directly behind the Earth into its umbra ( shadow ) . This can occur only when the sun , Earth , and moon are aligned ( in `` syzygy '' ) exactly , or very closely so , with the Earth in the middle . Hence , a lunar eclipse can occur only the night of a full moon . The type and length of an eclipse depend upon the Moon 's location relative to its orbital nodes .
Lunar distance (astronomy)
By recording the instant when the Moon occults a background star , ( or similarly , measuring the angle between the moon and a background star at a predetermined moment ) the lunar distance can be determined , as long as the measurements are taken from multiple locations of known separation .
Sundial
Another type of sundial follows the motion of a single point of light or shadow , which may be called the nodus . For example , the sundial may follow the sharp tip of a gnomon 's shadow , e.g. , the shadow - tip of a vertical obelisk ( e.g. , the Solarium Augusti ) or the tip of the horizontal marker in a shepherd 's dial . Alternatively , sunlight may be allowed to pass through a small hole or reflected from a small ( e.g. , coin - sized ) circular mirror , forming a small spot of light whose position may be followed . In such cases , the rays of light trace out a cone over the course of a day ; when the rays fall on a surface , the path followed is the intersection of the cone with that surface . Most commonly , the receiving surface is a geometrical plane , so that the path of the shadow - tip or light - spot ( called declination line ) traces out a conic section such as a hyperbola or an ellipse . The collection of hyperbolae was called a pelekonon ( axe ) by the Greeks , because it resembles a double - bladed ax , narrow in the center ( near the noonline ) and flaring out at the ends ( early morning and late evening hours ) . Declination
Moon landing
An unexpected major discovery from initial lunar orbiters were vast volumes of dense materials beneath the surface of the Moon 's maria . Such mass concentrations ( `` mascons '' ) can send a manned mission dangerously off course in the final minutes of a Moon landing when aiming for a relatively small landing zone that is smooth and safe . Mascons were also found over a longer period of time to greatly disturb the orbits of low - altitude satellites around the Moon , making their orbits unstable and forcing an inevitable crash on the lunar surface in the relatively short period of months to a few years .