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Astronomy Topics

Absorption Lines
Dark lines in a spectrum that are produced when light or other electromagnetic radiation passes through a gas cloud or similar object closer to the observer.
Accretion
The process by which the terrestrial planets grew.
Active Sun
The Sun during its 11-year cycle of activity when spots, flares, prominences, and variations in radio frequency radiation are at a maximum.
Adaptive Optics
A technique that uses deformable mirrors on a telescope to correct the blurring caused by turbulence in the atmosphere.
Apocentre
The point on a spacecraft′s orbit at which it is furthest away from the body it is orbiting.
Astrometry
The branch of astronomy concerned with measuring the positions of celestial bodies, such as stars and galaxies, and their real and apparent motions.
Astronaut
A person who rides in a space vehicle.
Binary Star
Pair of stars bound together by mutual gravitation and orbiting their common centre of mass.
Black Hole
A massive star that has collapsed to such a small size that its gravitational force is so strong that not even light can escape from its 'surface'.
Blue Supergiant
A supergiant star with spectral type O or B.
Bow Shock
The shock wave caused by the edge our Solar System travelling through deep space.
Brahe, Tycho
Danish astronomer who made precise observations of the sky.
Carbonado
Carbon that has metamorphosed into its diamond phase but remains black.
Cassegrain Telescope
Two-mirror reflecting telescope.
Cataclysmic Variable
A binary star system containing a white dwarf that exhibits sudden outbursts of energy.
Celestial Sphere
An imaginary sphere of infinite radius centered on the Earth and poles aligned with the poles of the Earth.
Decaying Orbit
An unstable orbit from which the orbiting object will gradually spiral into the body it is orbiting.
Earth
The basic Earth data.
Evening Star
Name given to Venus when observed in the evening, also known as Phosphorus.
Faculae
Bright granular structures on the surface of the Sun that are slightly hotter than the surrounding photosphere.
Faint Young Sun Paradox
Calculations suggest that at about the time of the formation of Earth, the Sun was roughly two-thirds the brightness that it is now. However, there is no geological evidence.
Galaxy Clusters
Groups of galaxies that may contain up to a few thousand galaxies.
Heliopause
The boundary between the solar wind and the interstellar wind, where the pressure of both are in balance.
Heliosheath
A vast, turbulent expanse where the solar wind piles up as it presses outward against interstellar matter.
Jupiter
The largest planet in our solar system.
Keplers Laws
Kepler found three laws defining the orbit of planets.
Kerr Black Hole
A rotating black hole.
Lunar Eclipse
When the Moon enters the Earth′s shadow as the Earth moves between the Sun and the Moon.
ly
Abbreviation of Light Year.
Mars
The fourth planet from the sun in our solar system.
Mercury
The planet nearest to the sun in our solar system.
Meteor
A meteoroid that has entered Earth′s atmosphere.
Meteorite
The remnants of a meteor after it has actually impacted the Earth.
Meteoroid
An object in space similar to but smaller than an asteroid.
Moon
Basic Moon data.
Morning Star
Name given to Venus when observed in the morning, also known as Hosperus.
Neptune
The outermost gas giant in our solar system.
Neutron Star
A star composed only of neutrons.
North Pole
That end of the axis of rotation of a celestial body at which, when viewed from above, the body appears to rotate in a counter-clockwise direction.
Nova
A star which suddenly becomes many times brighter than previously, and then gradually fades.
Opposition
The point at which a planet that is further away from the Sun than the Earth.
Orbit Acquisition
Reception of the telemetry containing the information about the orbital parameters of the spacecraft.
Planet
A spherical ball of rock and/or gas that orbits a star.
Pluto
The outermost planet in our solar system and it′s double Charon.
Protoplanetary Disc
The disc of dust surrounding a star out of which planets might form.
Pulsar
A stellar source, such as a rotating single star or pair of stars, emitting electromagnetic radiation which is characterised by rapid frequency and regularity.
Red Supergiant
A supergiant with spectral type M. These are the largest stars in the universe.
Reflecting Telescope
A type of telescope using a mirror as the objective.
Refracting Telescope
A type of telescope using a lens as the objective.
Satellite
An object in an orbit around a planet.
Saturn
The sixth planet from the sun in our solar system.
Schwarzschild Black Hole
A nonrotating, spherical black hole that has no electric charge.
Solar Eclipse
When the Earth enters the Moon′s shadow as the Moon moves wholly or partially in front of the Sun as seen from Earth.
Standing Wave
The interference pattern produced by two waves of equal amplitude and frequency traveling in opposite directions.
Star
A ball of mostly hydrogen and helium gas that shines extremely brightly. Our Sun is a star.
Starburst Galaxy
Galaxy in which a large burst of star formation is observed.
Stellar
Of the stars.
Stellar Wind
A steady or unsteady outflow of material from the surface of a star.
Sun
The star at the centre of our solar system.
Sunspot
An area on the surface of the sun marked by a lower temperature than its surroundings and that has magnetic activity.
Telescope
Instrument used to focus electromagnetic radiation into an image.
Termination Shock
Particles from the Sun begin to slow and clash with matter from the sparse gas found between the stars.
Uranus
The seventh planet from the sun in our solar system.
Yellow Supergiant
A supergiant star with a spectral type of G.
Zenith Telescope
Instrument for observing stars near the zenith.

See also: Astrophysics.

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