A group of Astrology definitions at Grade 9 level.
What is an Astronomer?
A scientist who studies Astronomy
What is a Celestial Object?
A Celestial Object is any object that exists in space.
What is Revolution?
Revolution is the time it takes for an object to orbit another object.
What is Rotation?
The turning of an object around an imaginary axis running through it.
What is a Constellation?
A constellation is a group of stars that seem to form a distinctive pattern in the sky.
What is Apparent Magnitude?
Apparent Magnitude is the brightness of a star as seen from Earth.
What is Latitude?
The location above or below the Equator.
What is a Light-Year?
The distance that light travels in one year. About 9.5*1012 km.
What are Tides?
The Rising and falling of ocean waters caused by the Moon's and Earth's gravity.
What is an Eclipse?
The phenomenon in which one celestial object moves directly in front of another celestial object.
What are phases of the moon?
The monthly progression of changes in the appearance of the Moon that result from different portions of the Moon's sunlit side being visible from Earth.
What is an Ellipse?
An ellipse is a curve that is generally referred to as being oval or the shape of an egg.
What is a Lunar Eclipse?
A lunar eclipse is the phenomenon in which the full Moon passes into Earth's shadow.
What is a Solar Eclipse?
The phenomenon in which the shadow of the Moon falls on Earth's surface.
What is an astronomical unit?
An astronomical unit is the average distance between the Earth and Sun.
What is Orbital Radius?
Orbital radius is the average distance between the Sun and an object that's orbiting the Sun.
What is a Planet?
A planet is an object that orbits one or more stars (and is not a star itself), is spherical, and doesn't share its orbit with another object.
What is retrograde motion?
Retrograde motion is the movement of an object in the sky, usually a planet, from eat to west, rather than its normal motion from west to east; this effect is generally produced when Earth is passing the planet in its orbit.
What is a Solar System?
a Solar System is a group of planets that circle one or more stars.
What is an asteroid?
An asteroid is an object in space that ranges in size from a tiny speck, like a grain of sand, to 500 km wide; most asteroids originate in the asteroid belt between Mars and Jupiter.
What is a Comet?
A comet is an object composed of rocky material, ice, and gas; comes from the Kuiper Belt or Oort Cloud.
What is a Meteoroid?
A meteoroid is a piece of rock moving through space.
What is a Meteor?
A meteor is a meteoroid that hits Earth's atmosphere and burns up.
What is a Meteorite?
A meteorite is a meteoroid that is large that is large enough to pass through Earth's atmosphere and reach the ground, without being totally burned up.
What is Electromagnetic Radiation?
Radiation consisting of electromagnetic waves, including radio waves, infrared, visible light, ultraviolet, x-rays, and gamma rays travelling at the speed of light.
What is a Reflecting Telescope?
A telescope that uses mirrors to collect the light from an object.
What is a Refracting Telescope?
A telescope that uses a lens to collect the light from an object.
What is a Satellite?
An artificial (human-made) object that orbits Earth, the Moon, or other celestial bodies; also a celestial body that orbits another body of larger size.
What is Solar Nebula Theory?
The theory that describes how stars and planets form from contracting, spinning disks of gas and dust.
What is a Star Nebula?
Also called diffuse nebula. A cloud of interstellar gas and dust.
What is a Sunspot?
An area of strong magnetic fields on the Sun's photosphere. (Black dots) Periodically visible due to our revolution of the Sun and the Sun's rotation.
What is Solar Wind?
A stream of fast-moving charged particles ejected by the Sun into the solar system.
What is a Spectroscope?
An optical instrument that produces a spectrum from a narrow beam of light, and usually projects the spectrum onto a photographic plate or a digital detector.
What are Spectral Lines?
Certain specific wavelengths within a spectrum characterized by lines; spectral lines identify specific chemical elements.
What is an H-R Diagram?
The graph showing the absolute magnitude plotted against the surface temperature for a group of stars.
What is a Protostar?
A hot, condensed object at the centre of a nebula.
What is Nuclear Fusion?
The process of energy production in which hydrogen nuclei combine to form helium nuclei.
What is a Photoshpere?
The Sun's surface.
What is Luminosity?
A star's total energy output per second; its power in joules per second (J/s)
What is Absolute Magnitude?
The magnitude of a star that we would observe if the star were 32.6 light-years from Earth.
What is the Mliky Way?
The galaxy that includes our solar system; appears as a hazy-white band in the night sky.
What is a Galaxy?
A huge collection of stars, planets, dust and gas that is held together by gravity.
What is a Star Cluster?
A collection of stars held together by gravity.
What is an Open Cluster?
A collection of 50-100 stars; open clusters appear along the main band of the milky way.
What is a Globular Cluster?
A collection of 100'000 to a million stars that is arranged in a distinctive spherical shape; globular clusters are around the centre of the milky way.
What is a Local Group?
The small group of 40 galaxies that includes the milky way.
What is a Supercluster?
A giant cluster of 4-25 galaxies that is hundreds of millions of light-years in size.
What is Cosmology?
The study of the Universe
What is the Doppler Effect?
The change in pitch of sound due to the motion of the source relative to an observer; also, the change in frequency of light source due to its motion relative to an observer.
What is a Redshift?
The effect in which objects moving away from an observer have their wavelengths lengthened, toward the red end of the visible spectrum.
What is Cosmic Microwave Background Radiation?
The radiation left over from the Big Bang, which fills the Universe.
What is Blueshift?
The effect in which objects moving toward an observer have their wavelengths shortened, toward the blue end of the visible spectrum.
What is the Big Bang?
The event that may have triggered the expansion of the Universe 14 billion years ago.