{"/e/orbits-and-celestial-mechanics/equinox/": {"t": "Equinox", "s": "Twice-yearly moment when day and night are nearly equal worldwide.", "i": "https://codexery.com/orbits-and-celestial-mechanics/img/orbits-and-celestial-mechanics/equinox.webp", "c": "江戸村のとくぞう · CC0"}, "/e/orbits-and-celestial-mechanics/equinox-celestial-coordinates/": {"t": "Equinox (celestial coordinates)", "s": "A direction in space, not a moment in time.", "i": "https://codexery.com/orbits-and-celestial-mechanics/img/orbits-and-celestial-mechanics/equinox-celestial-coordinates.webp", "c": "Timmonswilliams · CC0"}, "https://codexery.com/planets-and-dwarf-planets/e/planets-and-dwarf-planets/earth/": {"t": "Earth", "s": "The only known planet with liquid surface water and life."}, "https://codexery.com/named-stars/e/named-stars/sun/": {"t": "Sun", "s": "The Sun is the central star of the Solar System."}, "https://codexery.com/lines-hemispheres/e/lines-and-hemispheres/northern-hemisphere/": {"t": "Northern Hemisphere", "s": "The Northern Hemisphere contains most of the world's continents and major landmasses.", "i": "https://codexery.com/lines-hemispheres/img/lines-and-hemispheres/northern-hemisphere.webp", "c": "Sean Baker ( Marvin01 | talk ) · via Wikipedia: Northern Hemisphere · CC BY 2.0"}, "https://codexery.com/planets-stellar-astronomy/e/planets-and-stellar-astronomy/solar-system/": {"t": "Solar System", "s": "The Sun and all objects gravitationally bound to it.", "i": "https://codexery.com/planets-stellar-astronomy/img/planets-and-stellar-astronomy/solar-system.webp", "c": "via Wikipedia: Solar System · see source"}, "https://codexery.com/stars-and-stellar-objects/e/stars-and-stellar-objects/barycenter-astronomy/": {"t": "Barycenter (astronomy)", "s": "Dynamical point representing the center of mass of orbiting bodies."}, "/e/orbits-and-celestial-mechanics/orbital-eccentricity/": {"t": "Orbital eccentricity", "s": "Parameter measuring deviation of an orbit from a perfect circle."}, "https://codexery.com/ancient-greek-astronomy/e/ancient-greek-astronomy/heliocentrism/": {"t": "Heliocentrism", "s": "Superseded model placing Sun at universe's center."}, "https://codexery.com/ancient-greek-astronomy/e/ancient-greek-astronomy/geocentrism/": {"t": "Geocentrism", "s": "Earth-centered model of the cosmos, dominant for over 1,500 years."}, "https://codexery.com/astronomers-and-cosmologists/e/astronomers-and-cosmologists/aristarchus-of-samos/": {"t": "Aristarchus of Samos", "s": "Ancient Greek astronomer who first proposed a Sun-centered universe."}, "https://codexery.com/scientists-and-mathematicians/e/scientists-and-mathematicians/nicolaus-copernicus/": {"t": "Nicolaus Copernicus", "s": "Renaissance polymath who proposed the Sun-centered model of the universe."}, "https://codexery.com/ancient-greek-astronomers/e/ancient-greek-astronomers/ptolemy/": {"t": "Ptolemy", "s": "Greco-Roman scholar who authored the Almagest and Geography."}, "https://codexery.com/lines-hemispheres/e/lines-and-hemispheres/antarctic-circle/": {"t": "Antarctic Circle", "s": "Southernmost major latitude circle marking the Antarctic region."}, "https://codexery.com/astronomical-concepts-and-techniques/e/astronomical-concepts-and-techniques/solstice/": {"t": "Solstice", "s": "Twice-yearly event when the Sun's declination appears to stand still."}, "https://codexery.com/classical-mechanics/e/classical-mechanics/gravity/": {"t": "Gravity", "s": "Gravity is the fundamental attraction between objects with mass.", "i": "https://codexery.com/classical-mechanics/img/classical-mechanics/gravity.webp", "c": "https://commons.wikimedia.org/wiki/User:Nicoguaro · CC BY-SA 3.0"}, "https://codexery.com/scientists-and-mathematicians/e/scientists-and-mathematicians/pierre-simon-laplace/": {"t": "Pierre-Simon Laplace", "s": "French polymath who advanced celestial mechanics, probability, and the nebular hypothesis."}, "https://codexery.com/historical-figures/e/notable/carl-friedrich-gauss/": {"t": "Carl Friedrich Gauss", "s": "German mathematician, astronomer, geodesist, and physicist"}, "/e/orbits-and-celestial-mechanics/ecliptic/": {"t": "Ecliptic", "s": "Apparent path of the Sun on the celestial sphere.", "i": "https://codexery.com/orbits-and-celestial-mechanics/img/orbits-and-celestial-mechanics/ecliptic.webp", "c": "S.fonsi · CC BY-SA 3.0"}, "/e/orbits-and-celestial-mechanics/orbital-period/": {"t": "Orbital period", "s": "Time for one full orbit around a primary body."}, "https://codexery.com/astronomy-space/e/astronomy-and-space/lunar-eclipse/": {"t": "Lunar eclipse", "s": "A lunar eclipse occurs when the Moon passes through Earth's shadow."}, "https://codexery.com/languages-and-dialects/e/languages-and-dialects/greek-language/": {"t": "Greek language", "s": "Greek is the world's oldest recorded living language."}, "/e/orbits-and-celestial-mechanics/orbit-of-the-moon/": {"t": "Orbit of the Moon", "s": "The Moon's orbit is a stable, complex path studied by lunar theory."}, "/e/orbits-and-celestial-mechanics/earth-s-orbit/": {"t": "Earth's orbit", "s": "Earth's elliptical orbit around the Sun defines the year and seasons."}, "/e/orbits-and-celestial-mechanics/orbital-inclination/": {"t": "Orbital inclination", "s": "Angle measuring tilt of an orbit relative to a reference plane."}, "https://codexery.com/earth/e/earth/earth-s-shadow/": {"t": "Earth's shadow", "s": "Earth's shadow is a dark band visible opposite the Sun during twilight."}, "https://codexery.com/units-measurement/e/units-and-measurement/year/": {"t": "Year", "s": "A unit of time based on Earth's orbit around the Sun."}, "https://codexery.com/astronomical-concepts-and-techniques/e/astronomical-concepts-and-techniques/saros-astronomy/": {"t": "Saros (astronomy)", "s": "An eclipse cycle of 223 synodic months (about 18 years 11 days 8 hours) used to predict nearly identical solar and lunar eclipses."}, "https://codexery.com/astrology/e/astrology/ephemeris/": {"t": "Ephemeris", "s": "Tables of celestial positions used in astronomy and astrology."}, "https://codexery.com/astronomical-concepts-and-techniques/e/astronomical-concepts-and-techniques/zodiac/": {"t": "Zodiac", "s": "A celestial coordinate system dividing the ecliptic into 12 signs."}, "https://codexery.com/lines-hemispheres/e/lines-and-hemispheres/equator/": {"t": "Equator", "s": "Imaginary line dividing Earth into Northern and Southern Hemispheres."}, "https://codexery.com/astronomical-concepts-and-techniques/e/astronomical-concepts-and-techniques/sidereal-time/": {"t": "Sidereal time", "s": "Timekeeping system based on Earth's rotation relative to the fixed stars."}, "https://codexery.com/classical-mechanics-and-dynamics/e/classical-mechanics-and-dynamics/rotation/": {"t": "Rotation", "s": "Rotational motion leaves at least one point unchanged."}, "https://codexery.com/earth/e/earth/earth-s-rotation/": {"t": "Earth's rotation", "s": "Earth spins eastward, slowing over time but recently accelerating."}, "https://codexery.com/classical-and-fluid-mechanics/e/classical-and-fluid-mechanics/precession/": {"t": "Precession", "s": "A change in the orientation of a rotating body's rotational axis."}, "https://codexery.com/geometry-and-shapes/e/geometry-and-shapes/spherical-coordinate-system/": {"t": "Spherical coordinate system", "s": "A system using distance and two angles to locate points in space."}, "https://codexery.com/earth/e/earth/earth-radius/": {"t": "Earth radius", "s": "Distance from Earth's center to its surface, varying by location."}, "https://codexery.com/planets-and-dwarf-planets/e/planets-and-dwarf-planets/mars/": {"t": "Mars", "s": "The fourth planet from the Sun, a desert world with polar ice caps."}, "https://codexery.com/stars-and-stellar-objects/e/stars-and-stellar-objects/constellation/": {"t": "Constellation", "s": "Patterns in the sky that guide stories and navigation."}, "https://codexery.com/science-measurement/e/science-and-measurement/telescope/": {"t": "Telescope", "s": "Observing the universe across the electromagnetic spectrum", "i": "https://codexery.com/science-measurement/img/science-and-measurement/telescope.webp", "c": "Pelligton · CC BY-SA 4.0"}, "https://codexery.com/astrophotography/e/astrophotography/equatorial-mount/": {"t": "Equatorial mount", "s": "A mount that tracks celestial objects by aligning with Earth's rotation."}, "https://codexery.com/lines-hemispheres/e/lines-and-hemispheres/latitude/": {"t": "Latitude", "s": "Latitude specifies north-south position on Earth or celestial bodies.", "i": "https://codexery.com/lines-hemispheres/img/lines-and-hemispheres/latitude.webp", "c": "source: Pearson Scott Foresman, donated to the Wikimedia Foundation\nsvg conversion: Gregors\nColor: Jahobr · via Wikipedia: Latitude · Public domain"}, "https://codexery.com/lines-hemispheres/e/lines-and-hemispheres/east/": {"t": "East", "s": "Cardinal direction of sunrise, opposite west, abbreviated as E."}, "https://codexery.com/lines-hemispheres/e/lines-and-hemispheres/west/": {"t": "West", "s": "Cardinal direction opposite east, where the Sun sets."}, "https://codexery.com/ancient-inventions/e/ancient-inventions/sundial/": {"t": "Sundial", "s": "A device that tells time using the Sun's shadow or light."}, "https://codexery.com/lines-hemispheres/e/lines-and-hemispheres/southern-hemisphere/": {"t": "Southern Hemisphere", "s": "The Southern Hemisphere is Earth's southern half, mostly ocean."}, "https://codexery.com/ancient-mysteries/e/ancient-mysteries/the-antikythera-mechanism/": {"t": "The Antikythera Mechanism", "s": "The Antikythera mechanism is an ancient Greek hand-powered orrery, the oldest known analogue computer, used to predict astronomical positions and eclipses."}, "https://codexery.com/earth/e/earth/subsolar-point/": {"t": "Subsolar point", "s": "Point where the Sun is directly overhead, casting no shadow."}, "https://codexery.com/historical-figures/e/notable/julius-caesar/": {"t": "Julius Caesar", "s": "Roman general, dictator, and author who transformed the Republic."}, "https://codexery.com/astronomical-concepts-and-techniques/e/astronomical-concepts-and-techniques/tropical-year/": {"t": "Tropical year", "s": "Time for Sun to return to same seasonal position."}, "https://codexery.com/european-prime-ministers-and-statesmen/e/european-prime-ministers-and-statesmen/pope-gregory-xiii/": {"t": "Pope Gregory XIII", "s": "The pope who gave us the calendar"}, "https://codexery.com/astronomy-space/e/astronomy-and-space/orbit/": {"t": "Orbit", "s": "Curved trajectory of an object under an attracting force."}, "https://codexery.com/historical-figures/e/notable/hipparchus/": {"t": "Hipparchus", "s": "Greek astronomer, geographer, and mathematician; founder of trigonometry and discoverer of the precession of the equinoxes."}, "https://codexery.com/variable-stars/e/variable-stars/spica/": {"t": "Spica", "s": "Brightest star in Virgo, a close binary Beta Cephei variable."}, "https://codexery.com/ancient-greek-astronomers/e/ancient-greek-astronomers/timocharis/": {"t": "Timocharis", "s": "Greek astronomer whose observations enabled discovery of precession."}, "https://codexery.com/discoverers-of-astronomical-objects/e/discoverers-of-astronomical-objects/james-bradley/": {"t": "James Bradley", "s": "English astronomer and priest, third Astronomer Royal."}, "https://codexery.com/lines-hemispheres/e/lines-and-hemispheres/celestial-pole/": {"t": "Celestial pole", "s": "Fixed points in the sky around which all stars appear to rotate."}, "/e/orbits-and-celestial-mechanics/orbital-elements/": {"t": "Orbital elements", "s": "Parameters that uniquely identify a specific orbit."}, "https://codexery.com/astronomical-catalogues/e/astronomical-catalogues/astronomical-almanac/": {"t": "Astronomical Almanac", "s": "Joint UK/US almanac providing fundamental astronomical data worldwide.", "i": "https://codexery.com/astronomical-catalogues/img/astronomical-catalogues/astronomical-almanac.webp", "c": "US Naval Observtory. Copyright page indicates this page was one of those by US N · Public domain"}, "https://codexery.com/classical-mechanics-and-dynamics/e/classical-mechanics-and-dynamics/kinetic-energy/": {"t": "Kinetic energy", "s": "Energy of motion, quantified as ½mv² in classical mechanics."}, "https://codexery.com/exploration-of-mars/e/exploration-of-mars/heliocentric-orbit/": {"t": "Heliocentric orbit", "s": "An orbit around the Sun, followed by planets, comets, asteroids, and many artificial probes."}, "https://codexery.com/electromagnetism-and-radiation/e/electromagnetism-and-radiation/radiation-pressure/": {"t": "Radiation pressure", "s": "Mechanical pressure from electromagnetic radiation momentum exchange."}, "https://codexery.com/relativity-and-gravitation/e/relativity-and-gravitation/gravitational-constant/": {"t": "Gravitational constant", "s": "Fundamental constant quantifying gravitational force strength.", "i": "https://codexery.com/relativity-and-gravitation/img/relativity-and-gravitation/gravitational-constant.webp", "c": "National Institute of Standards and Technology · Public domain"}, "https://codexery.com/black-holes/e/black-holes/schwarzschild-metric/": {"t": "Schwarzschild metric", "s": "Exact solution to Einstein's equations for a spherical mass."}, "https://codexery.com/space-program-of-france/e/space-program-of-france/guiana-space-centre/": {"t": "Guiana Space Centre", "s": "European spaceport in South America near the equator."}, "https://codexery.com/astronomy-space/e/astronomy-and-space/low-earth-orbit/": {"t": "Low Earth orbit", "s": "Low Earth orbit hosts most artificial satellites and space stations."}, "https://codexery.com/classical-mechanics/e/classical-mechanics/momentum/": {"t": "Momentum", "s": "Vector quantity equal to mass times velocity."}, "https://codexery.com/earth/e/earth/earth-mass/": {"t": "Earth mass", "s": "A standard astronomical unit equal to the mass of Earth."}, "https://codexery.com/satellites/e/satellites/satellite/": {"t": "Satellite", "s": "Artificial objects placed into orbit around a celestial body."}, "/e/orbits-and-celestial-mechanics/orbital-station-keeping/": {"t": "Orbital station-keeping", "s": "Keeping spacecraft in orbit through precise thruster maneuvers."}, "https://codexery.com/classical-mechanics/e/classical-mechanics/drag-physics/": {"t": "Drag (physics)", "s": "A force opposing motion through a fluid, dependent on velocity.", "i": "https://codexery.com/classical-mechanics/img/classical-mechanics/drag-physics.webp", "c": "Nubifer // Wiki LIC (Spanish translation) · CC0"}, "/e/orbits-and-celestial-mechanics/geostationary-orbit/": {"t": "Geostationary orbit", "s": "A fixed point in the sky for global communications and observation.", "i": "https://codexery.com/orbits-and-celestial-mechanics/img/orbits-and-celestial-mechanics/geostationary-orbit.webp", "c": "NOAA · Public domain"}, "https://codexery.com/satellite-imagery/e/satellite-imagery/earth-observation-satellite/": {"t": "Earth observation satellite", "s": "Satellites that observe Earth from orbit for diverse applications."}, "https://codexery.com/successful-space-missions/e/successful-space-missions/apollo-15/": {"t": "Apollo 15", "s": "First J mission with rover, deep-space spacewalk, and Genesis Rock.", "i": "https://codexery.com/successful-space-missions/img/successful-space-missions/apollo-15.webp", "c": "NASA · Public domain"}, "https://codexery.com/apollo-16/e/apollo-16/apollo-16/": {"t": "Apollo 16", "s": "Fifth crewed lunar landing, second J mission, explored Descartes Highlands."}, "https://codexery.com/earth/e/earth/gravity-of-earth/": {"t": "Gravity of Earth", "s": "Earth's gravity varies by location due to rotation and shape."}, "https://codexery.com/earth/e/earth/figure-of-the-earth/": {"t": "Figure of the Earth", "s": "Models of Earth's size and shape for geodesy."}, "/e/orbits-and-celestial-mechanics/geosynchronous-orbit/": {"t": "Geosynchronous orbit", "s": "An Earth orbit synchronized with the planet's rotation.", "i": "https://codexery.com/orbits-and-celestial-mechanics/img/orbits-and-celestial-mechanics/geosynchronous-orbit.webp", "c": "MikeRun · CC BY-SA 4.0"}, "https://codexery.com/british-inventors/e/british-inventors/arthur-c-clarke/": {"t": "Arthur C. Clarke", "s": "Prophet of the Space Age and co-writer of 2001: A Space Odyssey."}, "https://codexery.com/antenna-types/e/antenna-types/satellite-dish/": {"t": "Satellite dish", "s": "Parabolic antenna for satellite communication, notably direct-broadcast television."}, "https://codexery.com/satellite-meteorology/e/satellite-meteorology/weather-satellite/": {"t": "Weather satellite", "s": "Satellites monitoring Earth's weather and climate from orbit."}, "/e/orbits-and-celestial-mechanics/graveyard-orbit/": {"t": "Graveyard orbit", "s": "A disposal orbit for end-of-life satellites to reduce debris.", "i": "https://codexery.com/orbits-and-celestial-mechanics/img/orbits-and-celestial-mechanics/graveyard-orbit.webp", "c": "cmglee · CC BY-SA 3.0"}, "https://codexery.com/narrative-forms-and-devices/e/narrative-forms-and-devices/science-fiction/": {"t": "Science fiction", "s": "Genre of speculative fiction about advanced technology and its consequences."}, "https://codexery.com/space-missions/e/space-missions/sputnik-1/": {"t": "Sputnik 1", "s": "Sputnik 1, meaning \"Satellite-One\" in Russian, was the first artificial Earth satellite."}, "https://codexery.com/radio-spectrum/e/radio-spectrum/high-frequency/": {"t": "High frequency", "s": "HF enables long-distance radio communication via ionospheric skywave propagation."}, "https://codexery.com/spacecraft-that-broke-apart-in-space/e/spacecraft-that-broke-apart-in-space/delta-rocket-family/": {"t": "Delta (rocket family)", "s": "American expendable launch system family, 1960–2024."}, "https://codexery.com/solar-phenomena/e/solar-phenomena/analemma/": {"t": "Analemma", "s": "A figure-eight diagram of the Sun's annual sky position."}, "https://codexery.com/phantom-places-discovery/e/phantom-places-and-discovery/remote-sensing/": {"t": "Remote sensing", "s": "Acquiring information about objects without physical contact."}, "https://codexery.com/radio-spectrum/e/radio-spectrum/microwave/": {"t": "Microwave", "s": "Electromagnetic radiation between radio waves and infrared, used widely in technology."}, "https://codexery.com/space-debris/e/space-debris/space-debris/": {"t": "Space debris", "s": "Defunct human-made objects in Earth orbit posing collision risks."}, "https://codexery.com/physical-geography-elevation/e/physical-geography-and-elevation/altitude/": {"t": "Altitude", "s": "Vertical distance measurement with context-dependent definitions and critical aviation applications.", "i": "https://codexery.com/physical-geography-elevation/img/physical-geography-and-elevation/altitude.webp", "c": "CVersteeg · CC BY-SA 4.0"}, "/e/orbits-and-celestial-mechanics/lissajous-orbit/": {"t": "Lissajous orbit", "s": "Quasi-periodic orbit around Lagrangian points used by spacecraft."}, "https://codexery.com/astronomy-space/e/astronomy-and-space/lagrange-point/": {"t": "Lagrange point", "s": "Equilibrium points for small objects in two-body gravitational systems."}, "https://codexery.com/space-telescopes/e/space-telescopes/space-telescope/": {"t": "Space telescope", "s": "Telescopes in space avoiding atmospheric interference for astronomical observation."}, "https://codexery.com/human-spaceflight-programs/e/human-spaceflight-programs/apollo-program/": {"t": "Apollo program", "s": "The United States human spaceflight program that landed the first humans on the Moon."}, "https://codexery.com/nasa-space-probes/e/nasa-space-probes/international-cometary-explorer/": {"t": "International Cometary Explorer", "s": "First spacecraft to visit a comet and first at a Lagrange point."}, "https://codexery.com/missions-to-the-sun/e/missions-to-the-sun/solar-and-heliospheric-observatory/": {"t": "Solar and Heliospheric Observatory", "s": "ESA-NASA solar observatory that discovered over 5,000 comets."}, "https://codexery.com/space-probes-of-esa-japan-china-india/e/space-probes-of-esa-japan-china-india-and-the-ussr/gaia-spacecraft/": {"t": "Gaia (spacecraft)", "s": "ESA astrometry mission mapping a billion stars."}, "https://codexery.com/moon-missions/e/moon-missions/chang-e-4/": {"t": "Chang'e 4", "s": "First spacecraft to soft-land on the far side of the Moon."}, "https://codexery.com/lunar-craters/e/lunar-craters/von-k-rm-n-lunar-crater/": {"t": "Von Kármán (lunar crater)", "s": "Large far-side crater, site of first lunar far-side soft-landing."}, "https://codexery.com/exoplanets/e/exoplanets/the-james-webb-space-telescope/": {"t": "The James Webb Space Telescope", "s": "The largest space telescope, observing the infrared universe from beyond Earth's orbit."}, "https://codexery.com/missions-to-the-sun/e/missions-to-the-sun/aditya-l1/": {"t": "Aditya-L1", "s": "First Indian solar observatory at Lagrange point 1."}, "https://codexery.com/geometry-and-shapes/e/geometry-and-shapes/tangent/": {"t": "Tangent", "s": "The line that just touches a curve at a point."}, "https://codexery.com/classical-mechanics-and-dynamics/e/classical-mechanics-and-dynamics/impulse-physics/": {"t": "Impulse (physics)", "s": "Vector quantity equal to the integral of force over time."}, "https://codexery.com/german-science-fiction-novels/e/german-science-fiction-novels/two-planets/": {"t": "Two Planets", "s": "Early Martian invasion novel by Kurd Lasswitz."}, "https://codexery.com/classical-mechanics-and-dynamics/e/classical-mechanics-and-dynamics/potential-energy/": {"t": "Potential energy", "s": "Energy stored in an object's position or configuration."}, "/e/orbits-and-celestial-mechanics/escape-velocity/": {"t": "Escape velocity", "s": "Minimum speed to escape a body's gravitational pull.", "i": "https://codexery.com/orbits-and-celestial-mechanics/img/orbits-and-celestial-mechanics/escape-velocity.webp", "c": "Richard West · CC BY-SA 2.0"}, "https://codexery.com/planets-and-dwarf-planets/e/planets-and-dwarf-planets/saturn/": {"t": "Saturn", "s": "Saturn is a gas giant with rings and the lowest density in the Solar System."}, "https://codexery.com/moons-of-saturn/e/moons-of-saturn/epimetheus-moon/": {"t": "Epimetheus (moon)", "s": "Co-orbital moon of Saturn that swaps orbits with Janus.", "i": "https://codexery.com/moons-of-saturn/img/moons-of-saturn/epimetheus-moon.webp", "c": "https://en.wikipedia.org/wiki/User:Jrkenti · CC BY-SA 3.0"}, "https://codexery.com/moons-of-saturn/e/moons-of-saturn/janus-moon/": {"t": "Janus (moon)", "s": "Saturn's co-orbital moon that swaps orbits with Epimetheus."}, "/e/orbits-and-celestial-mechanics/libration/": {"t": "Libration", "s": "Cyclic variation in Moon's apparent position revealing extra lunar surface."}, "https://codexery.com/castor-and-pollux/e/castor-and-pollux/polydeuces-moon/": {"t": "Polydeuces (moon)", "s": "Small trojan moon of Saturn trailing Dione."}, "https://codexery.com/moons-with-a-prograde-orbit/e/moons-with-a-prograde-orbit/dione-moon/": {"t": "Dione (moon)", "s": "Saturn's fourth-largest moon with icy cliffs and a possible subsurface ocean."}, "https://codexery.com/successful-space-missions/e/successful-space-missions/luna-3/": {"t": "Luna 3", "s": "First spacecraft to photograph the Moon's far side."}, "https://codexery.com/fifa-world-cup/e/honours/soviet-union/": {"t": "Soviet Union", "s": "The world's flagship communist state and a superpower spanning Eurasia."}, "/e/orbits-and-celestial-mechanics/halo-orbit/": {"t": "Halo orbit", "s": "Periodic, non-planar orbit around Lagrange points."}, "https://codexery.com/missions-to-the-sun/e/missions-to-the-sun/advanced-composition-explorer/": {"t": "Advanced Composition Explorer", "s": "NASA satellite studying solar wind and cosmic particles."}, "https://codexery.com/spacex-payloads-contracted-by-nasa/e/spacex-payloads-contracted-by-nasa/deep-space-climate-observatory/": {"t": "Deep Space Climate Observatory", "s": "NOAA's first operational deep space satellite for solar storm warnings."}, "https://codexery.com/nasa-space-probes/e/nasa-space-probes/wilkinson-microwave-anisotropy-probe/": {"t": "Wilkinson Microwave Anisotropy Probe", "s": "Mapped the cosmic microwave background to establish the standard cosmological model."}, "https://codexery.com/missions-to-the-sun/e/missions-to-the-sun/genesis-spacecraft/": {"t": "Genesis (spacecraft)", "s": "First NASA sample-return since Apollo, crashed but met science goals."}, "https://codexery.com/space-probes-of-esa-japan-china-india/e/space-probes-of-esa-japan-china-india-and-the-ussr/planck-spacecraft/": {"t": "Planck (spacecraft)", "s": "ESA observatory that mapped the cosmic microwave background with unprecedented precision."}, "https://codexery.com/ground-robots-and-military-robots/e/ground-robots-and-military-robots/themis/": {"t": "THeMIS", "s": "Estonian multi-mission UGV for military support and combat."}, "https://codexery.com/novels-by-stephen-baxter/e/novels-by-stephen-baxter/sunstorm-novel/": {"t": "Sunstorm 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"Australia's civil space agency focused on commercial growth."}, "/e/orbits-and-celestial-mechanics/frozen-orbit/": {"t": "Frozen orbit", "s": "An orbit minimizing perturbations for long-term stability.", "i": "https://codexery.com/orbits-and-celestial-mechanics/img/orbits-and-celestial-mechanics/frozen-orbit.webp", "c": "NASA/GSFC/Arizona State University · Public domain"}, "https://codexery.com/atmosphere/e/atmosphere/atmosphere/": {"t": "Atmosphere", "s": "A layer of gases enveloping an astronomical object, retained by gravity."}, "https://codexery.com/planets-and-dwarf-planets/e/planets-and-dwarf-planets/jupiter/": {"t": "Jupiter", "s": "Largest planet in the Solar System, a gas giant with a Great Red Spot."}, "https://codexery.com/classical-and-continuum-mechanics/e/classical-and-continuum-mechanics/tidal-force/": {"t": "Tidal force", "s": "Differential gravity stretches bodies and drives tides across the cosmos."}, "https://codexery.com/astronomy-space/e/astronomy-and-space/io-moon/": {"t": "Io (moon)", "s": "Io is Jupiter's innermost Galilean moon, the most volcanically active body known."}, "https://codexery.com/geometry-and-topology/e/geometry-and-topology/convex-set/": {"t": "Convex set", "s": "A set containing all line segments between its points."}, "https://codexery.com/classical-mechanics-and-dynamics/e/classical-mechanics-and-dynamics/frame-of-reference/": {"t": "Frame of reference", "s": "Abstract coordinate system for describing physical space and motion."}, "https://codexery.com/types-of-planet/e/types-of-planet/double-planet/": {"t": "Double planet", "s": "A binary system where both bodies are planetary-mass and orbit an external barycenter."}, "https://codexery.com/international-organizations-and-agreemen/e/international-organizations-and-agreements/international-astronomical-union/": {"t": "International Astronomical Union", "s": "Global authority for astronomical naming and cooperation."}, "https://codexery.com/cities/e/ancient-cities/babylon/": {"t": "Babylon", "s": "Ancient city on the Euphrates, heart of Babylonia and home of wonders."}, "https://codexery.com/historical-figures/e/notable/isaac-newton/": {"t": "Isaac Newton", "s": "English polymath who formulated laws of motion and universal gravitation."}, "https://codexery.com/electromagnetism-and-waves/e/electromagnetism-and-waves/electrostatics/": {"t": "Electrostatics", "s": "Branch of physics studying stationary electric charges and their forces."}, "https://codexery.com/mechanics-and-fluid-dynamics/e/mechanics-and-fluid-dynamics/kepler-problem/": {"t": "Kepler problem", "s": "Inverse-square central force problem in classical mechanics."}, "https://codexery.com/topology-and-abstract-spaces/e/topology-and-abstract-spaces/winding-number/": {"t": "Winding number", "s": "Integer count of a curve's counterclockwise turns around a point."}, "https://codexery.com/astronomy-space/e/astronomy-and-space/mercury-planet/": {"t": "Mercury (planet)", "s": "Smallest planet and closest to the Sun."}, "https://codexery.com/planets-and-dwarf-planets/e/planets-and-dwarf-planets/iau-definition-of-planet/": {"t": "IAU definition of planet", "s": "IAU definition reclassified Pluto as a dwarf planet in 2006."}, "https://codexery.com/planets-and-dwarf-planets/e/planets-and-dwarf-planets/pluto/": {"t": "Pluto", "s": "Dwarf planet in the Kuiper belt, once the ninth planet."}, "https://codexery.com/astronomy/e/astronomy/eris-dwarf-planet/": {"t": "Eris (dwarf planet)", "s": "Dwarf planet whose discovery redefined the Solar System's planetary lineup.", "i": "https://codexery.com/astronomy/img/astronomy/eris-dwarf-planet.webp", "c": "ESO/L. Calçada and Nick Risinger (skysurvey.org) · CC BY 4.0"}, "https://codexery.com/planets-and-dwarf-planets/e/planets-and-dwarf-planets/sedna-dwarf-planet/": {"t": "Sedna (dwarf planet)", "s": "A distant dwarf planet with the longest known orbital period."}, "https://codexery.com/planets-and-dwarf-planets/e/planets-and-dwarf-planets/neptune/": {"t": "Neptune", "s": "The only planet discovered through mathematical prediction, not direct observation."}, "https://codexery.com/moons-of-uranus-and-neptune/e/moons-of-neptune/triton-moon/": {"t": "Triton (moon)", "s": "Neptune's largest moon, captured from the Kuiper belt, with a retrograde orbit."}, "https://codexery.com/stars-and-stellar-objects/e/stars-and-stellar-objects/asteroid/": {"t": "Asteroid", "s": "Rocky, metallic, or icy minor planets orbiting the Sun, mostly in the main belt between Mars and Jupiter."}, "https://codexery.com/stars-and-stellar-objects/e/stars-and-stellar-objects/comet/": {"t": "Comet", "s": "Icy wanderers that bloom when near the Sun."}, "https://codexery.com/astronomy/e/astronomy/halley-s-comet/": {"t": "Halley's Comet", "s": "First comet recognized as periodic, observed for over two millennia.", "i": "https://codexery.com/astronomy/img/astronomy/halley-s-comet.webp", "c": "via Wikipedia: Halley's Comet · see source"}, "https://codexery.com/astronomy/e/astronomy/exoplanet/": {"t": "Exoplanet", "s": "An exoplanet, also called an extrasolar planet, is any planet that exists beyond our Solar System.", "i": "https://codexery.com/astronomy/img/astronomy/exoplanet.webp", "c": "European Space Agency · CC BY-SA 3.0 igo"}, "https://codexery.com/astronomy-space/e/astronomy-and-space/magnitude-astronomy/": {"t": "Magnitude (astronomy)", "s": "Logarithmic scale measuring stellar brightness, with lower values for brighter objects."}, "https://codexery.com/probability-statistics/e/probability-and-statistics/parameter/": {"t": "Parameter", "s": "A characteristic that helps define or classify a system.", "i": "https://codexery.com/probability-statistics/img/probability-and-statistics/parameter.webp", "c": "Yomomo · CC BY-SA 4.0"}, "https://codexery.com/computing-software/e/computing-and-software/punched-card/": {"t": "Punched card", "s": "Paper medium storing data via holes, used for computing and automation."}, "https://codexery.com/mathematicians/e/mathematicians/henri-poincar/": {"t": "Henri Poincaré", "s": "French polymath and last universalist mathematician.", "i": "https://codexery.com/mathematicians/img/mathematicians/henri-poincar.webp", "c": "via Wikipedia: Henri Poincaré · see source"}, "/e/orbits-and-celestial-mechanics/polar-orbit/": {"t": "Polar orbit", "s": "Satellite orbit passing near both poles each revolution.", "i": "https://codexery.com/orbits-and-celestial-mechanics/img/orbits-and-celestial-mechanics/polar-orbit.webp", "c": "NOAA · Public domain"}, "https://codexery.com/geometry-and-topology/e/geometry-and-topology/angle/": {"t": "Angle", "s": "A geometric figure formed by two lines meeting at a point."}, "https://codexery.com/types-of-planet/e/types-of-planet/terrestrial-planet/": {"t": "Terrestrial planet", "s": "Rocky planets with solid surfaces, including Earth and similar worlds."}, "https://codexery.com/types-of-planet/e/types-of-planet/gas-giant/": {"t": "Gas giant", "s": "Giant planets composed mainly of hydrogen and helium."}, "https://codexery.com/planets-stellar-astronomy/e/planets-and-stellar-astronomy/star-system/": {"t": "Star system", "s": "Gravitationally bound groups of stars, from binaries to complex multiples."}, "https://codexery.com/binary-and-multiple-stars/e/binary-and-multiple-stars/astrometric-binary/": {"t": "Astrometric binary", "s": "Some stars appear to circle an invisible point."}, "https://codexery.com/meteorology/e/meteorology/hertz/": {"t": "Hertz", "s": "German physicist who proved electromagnetic waves exist."}, "https://codexery.com/units-measurement/e/units-and-measurement/metre/": {"t": "Metre", "s": "Base SI unit of length, defined by light in vacuum."}, "https://codexery.com/chemical-elements/e/chemical-elements/tungsten/": {"t": "Tungsten", "s": "The element with the highest melting point of all known elements.", "i": "https://codexery.com/chemical-elements/img/chemical-elements/tungsten.webp", "c": "Jwcorone · CC BY-SA 3.0"}, "https://codexery.com/chemistry-materials/e/chemistry-and-materials/lead/": {"t": "Lead", "s": "Heavy metal with stable isotopes and historical industrial use."}, "https://codexery.com/moons-with-a-prograde-orbit/e/moons-with-a-prograde-orbit/europa-moon/": {"t": "Europa (moon)", "s": "Jupiter's icy moon with a subsurface ocean."}, "https://codexery.com/moons-of-jupiter/e/moons-of-jupiter/ganymede-moon/": {"t": "Ganymede (moon)", "s": "Largest moon in the Solar System, with its own magnetic field."}, "https://codexery.com/stars-and-stellar-objects/e/stars-and-stellar-objects/callisto-moon/": {"t": "Callisto (moon)", "s": "Second-largest moon of Jupiter, with a heavily cratered surface."}, "https://codexery.com/planets-stellar-astronomy/e/planets-and-stellar-astronomy/planetary-system/": {"t": "Planetary system", "s": "A star's family of orbiting worlds and debris."}, "https://codexery.com/planets-and-dwarf-planets/e/planets-and-dwarf-planets/definition-of-planet/": {"t": "Definition of planet", "s": "A contested term for celestial bodies, defined by orbit, roundness, and dominance."}, "https://codexery.com/classical-mechanics-and-dynamics/e/classical-mechanics-and-dynamics/newton-s-law-of-universal-gravitation/": {"t": "Newton's law of universal gravitation", "s": "Gravity as a universal force between all masses."}, "https://codexery.com/satellites/e/satellites/satellite-ground-track/": {"t": "Satellite ground track", "s": "The path on Earth directly below a satellite's orbit."}, "https://codexery.com/space-missions/e/space-missions/the-international-space-station/": {"t": "The International Space Station", "s": "The International Space Station (ISS) is a modular spacecraft in low Earth orbit, assembled and operated by five partner agencies: NASA, Roscosmos, ESA, JAXA, a"}, "https://codexery.com/inorganic-compounds-materials/e/inorganic-compounds-and-materials/hydrazine/": {"t": "Hydrazine", "s": "A versatile inorganic compound used in propellants, foams, and pharmaceuticals.", "i": "https://codexery.com/inorganic-compounds-materials/img/inorganic-compounds-and-materials/hydrazine.webp", "c": "Ben Mills · Public domain"}, "https://codexery.com/artemis-program/e/artemis-program/capstone/": {"t": "CAPSTONE", "s": "CubeSat that verified the Lunar Gateway's planned orbit."}, "https://codexery.com/crewed-spacecraft-and-space-stations/e/crewed-spacecraft-and-space-stations/lunar-gateway/": {"t": "Lunar Gateway", "s": "Planned lunar orbital station for Artemis program staging."}, "https://codexery.com/classical-mechanics/e/classical-mechanics/velocity/": {"t": "Velocity", "s": "A vector measure of speed with direction."}, "https://codexery.com/electromagnetism-and-waves/e/electromagnetism-and-waves/frequency/": {"t": "Frequency", "s": "Frequency measures repeating events per unit time."}, "https://codexery.com/classical-mechanics/e/classical-mechanics/torque/": {"t": "Torque", "s": "Torque is the rotational analogue of linear force."}}