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Earth Science Unit 5
Astronomy Vocabulary
Question | Answer |
---|---|
Geocentric Universe | The idea that Earth was at the center of the solar system |
Problems with the Geocentric Model: | Locations of the planets could not accurately be predicted |
Problems with the Geocentric Model: | Changes in the apparent diameter of the Moon and Sun could not be explained |
Celestial Object | any of the natural objects that can be seen in the sky |
Apparent Motion | the way in which celestial objects appear to move across the sky |
Celestial Sphere | the visible portion of the sky that celestial objects appear to travel on |
Horizon | the edge of the visible portion of the celestial sphere |
Zenith | highest point on the celestial sphere which is directly over the observer |
Star Trails | long exposure photos of stars as they move across the sky |
Circumpolar Stars | stars that move around a polar star |
Polar Star | star directly above the North or South Pole |
Altitude | angular distance above the horizon (0º to 90º) |
Azimuth - | angular distance along the horizon measured from due north (0º to 360º) |
Heliocentric Model | current model of the solar system where the Sun is at the center |
Rotation | the movement of an object in a circular motion around a line of axis |
Period of Rotation | amount of time to make one complete rotation Example: Earth rotates 360º in 24 hours |
Foucault Pendulum | large pendulum that when allowed to swing freely changes its path due to Earth’s rotation |
Coriolis Effect | the tendency of all particles on Earth’s surface to be deflected from a straight line |
Revolution | the motion of one body around another in an orbit |
Period of Revolution | the amount of time required to orbit the Sun one time Example: Earth orbits the Sun in 365.25 days |
Parallelism of Earth’s Axis | Earth’s tilted axis of 23.5º is always pointed to the same location in the sky giving us our different seasons |
Winter Solstice | first day of winter (December 21) in the N. Hemisphere when the Earth leans away from the Sun |
Summer Solstice | first day of summer (June 21) in the N. Hemisphere when the Earth leans towards the Sun |
Vernal Equinox | first day of spring (March 21) in the N. Hemisphere when there are equal amounts of day and night |
Autumnal Equinox | first day of fall (September 21) in the N. Hemisphere when there are equal amounts of day and night |
Ellipse | the oval shape of a planet’s orbits |
Eccentricity | the degree of flatness or “ovalness” of an ellipse |
Foci | two fixed center points of an ellipse |
Major Axis | longest straight lined distance across an ellipse |
Minor Axis | shortest straight lined distance across an ellipse |
Solar System | all the objects that orbit the Sun under its gravitational influence |
Terrestrial Planets | solid surfaced planets with smaller diameters and higher densities that are close to the Sun. Mercury-Venus- Earth- Mars |
Jovian Planets | gaseous planets with larger diameters and lower densities that are farther from the Sun. Jupiter-Saturn-Uranus-Neptune |
Asteroids | solid rocky or metallic bodies that independently orbit the Sun |
Moon | a body that orbits a planet or asteroid as they orbit the Sun |
Crescent Moon | phase that is part way between a half moon and new moon or between new moon and half moon |
Full Moon | phase that appears as an entire circle in the sky |
Gibbous Moon | phase that is part way between a full moon and half moon or between a half moon and full moon |
New Moon | phase where no part is visible from the Earth |
Waxing Moon | to increase in size (lit portion) gradually |
Waning Moon | to decrease in size (lit portion) gradually |
Comet | “dirty snowball” mainly composed of solids that easily change to a gas when heated |
Meteoroid | small fragment that orbits the Sun |
Meteorites | a rock that leaves a visible streak as they pass through our atmosphere and strike Earth |
Galaxy | a collection of billions of stars and various amounts of gas held together by gravity |
Milky Way Galaxy | our solar system is part of a spiral shaped galaxy with 200 billion stars |
Star | large ball of gas held together by gravity that produces tremendous amounts of energy and shines |
Nuclear Fusion | the combining of smaller elements to form the nuclei of larger elements |
Luminosity | a measure on how bright a star is compared to our Sun |
Main Sequence Star | average size, temperature, and luminosity stars |
Red Giant Stars | a luminous easily seen star that is in a late phase of stellar evolution |
Super Giant Stars | star with an extremely high temperatures in the late stages of its stellar evolution |
White Dwarf Stars | Earth sized star with a low luminosity and a hot surface |
Universe | all the space, matter, and energy that exists in any place |
Big Bang | states that all matter and energy started out concentrated in a small area and after a gigantic explosion, matter began to organize into subatomic particles and atoms |
Electromagnetic Energy | energy that is radiated through space in the forms of transverse waves |
Background Radiation | left over energy created by the explosion found in all parts of the universe |
Doppler Effect - | the apparent wave length shifting of electromagnetic energy caused by the relative motion between the energy source and the observer |
Blue Shift | when Earth and the celestial object are coming close together the spectral lines move towards the blue wavelength |
Red Shift | when Earth and the celestial object are moving apart the spectral lines move towards the red wavelength |