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Sci9 Space Glossary
Term | Definition |
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solstice | either of two times in the year when the sun reaches its highest or lowest point in the sky at noon in the northern hemisphere the summer solstice occurs near june 21 |
equinox | either of the two times a year (once in spring and once in autumn) when the Sun crosses the equator and day and night are of equal length; usually on or about March 21 and September 23 |
geocentric | the earth-central model of the solar system originally proposed about 200 years ago by the greek philosopher Aristotle |
heliocentric | the sun-centred model of the solar system first proposed by polish astronomer Nicholas Copernicus in 1530 |
ellipses | an oval formed around to foci(a circle formed around one focus); the orbital paths of planets travelling around the sun are ellipse |
astronomical unit | The astronomical unit is used for measuring “local” distances, those inside our solar system. One AU is equal to the average distance from the centre of earth to the centre of the sun (149 599 000). |
light-year | The distance the light travels in 1 year (Approximately 9.6 trillion Km) uses to measure distances between stars and galaxies. |
nebulae | Vast clouds of gas (mostly hydrogen) and dust in space, where stars form; Nebula. ( Singular) |
interstellar matter | The gases and dust that exist in the space between stars. |
protostar | A contracting mass mass if gas in the first stage of a star’s formation |
sun-like | One of the two main types of stars that can form (the other being massive stars, which are, by comparison, larger in mass than sun-like stars) |
massive star | One of the two types of stars that can form ( the other beimg sun-like stars, which are, by compression, smaller in mass than massive stars.) |
main sequence | On The Hertzsprung-Russell diagram, the stage in the life cycle of most stars during which they produce energy by converting hydrogen into helium; main sequence stars, including our sun, are sustainable stars, |
red giant | The stage in the life cycle of a sun-like star during which the star increases in size and becomes very bright. |
red supergiant | the stage in the life cycle of a massive star during which the star increases in size and becomes very bright |
white dwarf | one of the latter stages in the life cycle of a sun-like star during which the star collapses: white dwarfs are hot but very faint. |
black dwarf | the final phase in life cycle of a sun like star |
supernova | an enormous explosion that marks the death of a massive star |
neutron star | A small, super-dense remnant of a supernova |
black hole | a super-dense remnant of a supernova;an object around which gravity is so intense that even light cannot escape |
constellations | Groupings of stars that form patterns in the night sky |
asterisms | A distinctive star grouping that is not one of the 88 recognized star groupings |
galaxy | a grouping of millions or billions of stars,gas,dust held together by gravitiy |
solar wind | streams of electrically charged particles discharged by the Sun in every direction: solar wind passes Earth at nearly 400 km/s |
asteroids | small, rocky bodies orbiting the Sun and lying mainly in a narrow belt between Mars and Jupiter. |
comets | a celestial body composed of dust and ice that orbits the Sun; it has a bright centre and long, faint tail that always points away from the Sun |
meteoroids | a solid body usually a fragment of rock or metal travelling in space with no particular path |
meteor | A meteor that enters earth’s atmosphere, where the heat of friction causes it to glow brightly |
meteorite | The remains of a metoeorite that do not burn up completely and so last enough to hit Eath’s surface |
azimuth | Angle between the most northerly point of the horizon and the point directly below a celestial body; also the horizontal angle or direction of a compass bearing. |
altitude | height of a celestial body above the horizon, ranging from 0 at sea level to 90࿁ straight up |
Zenith | highest point in the sky directly overhead |
ecliptic | The apparent path of the sun and planets through stars during the year, as viewed from earth. |
microgravity | The condition in which the gravitational forces that act on a mass are greatly reduced. |
gravity | The force of attraction between masses |
satellites | a small body that orbits a larger one; satellite may be natural, such as a moon orbiting a planet, or artificial, such as a spacecraft put into orbit around earth by humans for research or communication purposes |
refracting telescope | A type of optical telescope that uses two lenses to gather and focus lights. |
reflecting telescopes | a optical lelescope that uses mirrors instead of lenses |
interferometry | technique of using telescopes in combination is known as interferometry |
Hubble Space Telescope | one of the largest, and most complex satellites ever built |
electromagnetic energy | Forms of radiated energy that travel at the speed of light (300 000 km/s) although they have different wavelengths and frequencies than light. |
electromagnetic spectrum | the complete range of wavelengths over which electromagnetic energy extends |
radio telescopes | A telescope system that collects and analyzes radiation in the radio frequency range from stars and other bodies in space. |
space probes | Unmanned satellites or remote-controlled “landers” used to explore areas or objects in space that are too difficult or dangerous to send humans to. |
triangulation | Triangulation is based on the geometry of a triangle. By measuring the angles between a baseline and the target object (such as a tall tree or a water tower) you can determine the distance to the object. |
parallax | The apparent shift in position of a nearby object against a distant background when the object is viewed from two different positions |
spectroscope | an instrument used by astronomers to observe and measure the spectrume of a star |
Doppler effect | the apparent change in frequency of sound light and other waves as the observer and the wave source move towards or away also referred to as Doppler shift . |
space junk | refers to all the pieces of debris that have fallen off rockets satellites space shuttles and space stations and remain floating in space |