Transcript Unit 2 Vocabulary

Unit 2 Vocabulary
1.) Astronomy – the scientific study of the universe; it includes
the observation and interpretation of celestial bodies and
phenomena.
2.) Geocentric – describes the concept of an Earth-centered
universe.
3.) Heliocentric – describes the view that the Sun is at the
center of the solar system
4.) Ellipse – an oval; the shape that the orbits of the planets
are thought to be.
5.) Astronomical Unit (AU)— the average distance from Earth
to the Sun
6.) Rotation – the spinning of a body, such as Earth, about its
axis (causes day/night)
7.) Revolution – the motion of one body around another, as
Earth around the Sun (causes the year).
8.) Precession – a slow motion of Earth’s axis that traces out a
cone over a period of 26,000 years.
9.) Solar Eclipse – an eclipse of the Sun; occurs when the
moon moves in a line directly between Earth and the Sun,
casting a shadow on Earth.
10.) Lunar Eclipse – an eclipse of the Moon; occurs when the
moon passes through Earth’s shadow.
11.) Terrestrial Planet – any of the Earth-like planets; Mercury,
Venus, Earth, and Mars
12.) Jovian Planet – huge gas-giants with relatively low
densities; Jupiter, Saturn, Uranus, and Neptune
13.) Nebula – a cloud of gas and/or dust in space.
14.) Meteoroid – a small, solid particle that travels through
space.
15.) Meteor— the luminous phenomenon observed when a
meteoroid enters Earth’s atmosphere and burns up; also
called a shooting star
16.) Meteorite – and portion of a meteoroid that reaches
Earth’s surface.
17.) Electromagnetic Spectrum – the arrangement of
electromagnetic radiation according to wavelength (Radio
waves, Infrared waves, Visible Light, UV, X-Rays, Gamma Rays)
18.) Light-Year – the distance light travels in a year, about 9.5
million kilometers
19.) Radiation – the transfer of energy (heat) through space by
electromagnetic waves).
20.) Galaxy – a group of stars, dust, and gases held together by
gravity.
21.) Aphelion – the place in the orbit of a planet where the
planet is farthest from the Sun.
22.) Perihelion - the point in the orbit of a planet where it is
closets to the Sun.
23.) Perigee – the point at which the Moon is closest to Earth.
24.) Apogee – the point at which the Moon is farthest from
Earth.
25.) Nuclear Fusion – the way in which the Sun produces
energy; when nuclei combine; tremendous amounts of
energy is released.
1.) Cosmic Rays – immensely high energy radiation, mainly
originating outside the Solar system
2.) Kepler’s Laws – support the theory and understanding of
our solar system.
a.) The path of each planet is an ellipse, the Sun at the
focus (center)
b.) Each planet revolves in an imaginary line over equal
areas (Must go faster when farther from the Sun and slower
when closer to the Sun)
c.) The time it takes the planet to orbit the Sun (orbital
period) is proportional to the distance from the Sun.
3.) Nutation – a periodic oscillation of the earth's axis that
causes the precession of the poles to follow a wavy path
rather than a circular path.
4.) Barycenter – is the center of mass of two or more bodies
that are orbiting each other
5.) Nuclear Fission – occurs when the nuclei split into smaller
nuclei and emit neutrons and heat energy.