Astronomy Flashcards
What does Astronomical Unit mean?
a distance equal to the average distance between Earth and the Sun
What does Light Year mean?
a unit of distance equal to the distance travelled by light in a single year
What does Parsec mean?
the distance from Earth at which stellar parallax would equal 1 second of arc
What is Nebula?
a cloud of interstellar gas and dust
What is Constellation?
any of the 88 groups of stars as viewed from Eath and the Solar System
What is Planetesimal ?
one small celestial body that was fused together to form the planets of the solar system
What is Protoplanetary?
protoplanets are moon-sized or larger planetary embryos within discs that have undergone internal melting to differentiated interiors
What is Nuclear Fusion?
Nuclear reaction when an atomic nuclei of low atomic number fue to form a heavier nucleus with the release of energy
What is Terrestrial Planets?
a planet which has characteristics of a rocky surface like the Earth’s
What are Gas Giant Planets?
a planet composed of almost entirely of gas
What is a Comet?
a celestial object of a nuclues of ice and dust, when near the sun a “tail” of gas/dust particles pointing away from the sun
What is Asteroid?
a small/rocky body that orbits the sun
What is a Cosmologist?
an astronomer who studies the evolution and space-time of the universe
What is Angular Velocity?
the rate of change of an angular position of a rotationg body
What is Orbit?
the curved path of a celestial object around a star, planet, or moon
What is Period?
a length of time
What does it mean to Revolve?
move in a circle/ on a central axis
What is a Rotation?
the action of rotating around an axis/center
What is the Sidereal Day?
the time between two consecutive transits of First Point of Aries
What is the Solar Day?
when Earth makes a complete rotation on its axis
What is a Year?
365 days
What is Accretion?
the drawing together of interstellar gas and surrounding objects by gravity in a celestial object
What is Spring Tide?
occurs when the Moon is either new or full and the Sun and Earth are aligned
What is Neap Tide?
occurs at the first and third quarters of the moon
What is Eccentricity?
the measure of an elliptical path , especially an orbit, from a perfect circle
What is Coma?
the shining cloud of gas that surrounds the nucleus and is the major portion of the head of the comet near the Sun
What is Precession?
the slow movement of the axis of a spinning body around another axis
What is an Orbital Plane?
the plane on which a body is orbiting
What is Inclination?
the degree of deviation from the horizontal or vertical
