Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
40 Cards in this Set
- Front
- Back
|
Ancient Greeks and Early Astronomy |
Used philosophical arguments to explain natural phenomena.
Also used some observational data. |
|
|
Ancient Greek's Geocentric View of the Universe |
Earth was a motionless sphere at the center of the universe. "Earth-Centered" - Stars were on the celestial sphere: Transparent, hollow sphere. Celestial sphere turns daily around Earth. 7 heavenly bodies (planetai): Changed position in the sky. The 7 wanderers: Sun, Moon, and Mercury through Saturn (excluding Earth). |
|
|
Aristarchus |
1st Greek to profess a Sun-centered (heliocentric) universe. |
|
|
Retrograde Motion |
An apparent westward drift that planets exhibit.
Occurs as Earth, with its faster orbital speed, overtakes another planet. |
|
|
Ptolemaic System |
Geocentric Model
To explain retrograde motion, Ptolemy used two motions for the planets. - Large orbital circles, called deferents, and - Small circles, called epicycles. |
|
|
Nicolaus Copernicus (1470-1540) |
Concluded Earth was a planet.
Constructed a model of the solar system that put the Sun at the center, but used circular orbits for the planets.
Ushered out old astronomy.` |
|
|
Tycho Brahe (1540-1600) |
Precise Observer.
Tried to find stellar parallax, the apparent shift in a star's position due to the revolution of Earth.
Didn't believe in the Copernican system because he was unable to observe stellar parallax. |
|
|
Johannes Kepler (1570-1630) |
Ushered in new astronomy. Planets revolve around the Sun.
3 Laws of Planetary Motion: 1. Orbits of the planets are elliptical. 2. Planets revolve around the Sun at varying speeds. 3. There's a relationship btwn a planet's orbital period and its distance to the Sun (measured in astronomical units (AU) - 1 AU averages about 150 million km or 93 million miles) |
|
|
Galileo Galilei (1565-1640) |
Supported Copernican theory. Used experimental data. Constructed an astronomical telescope in 1609: -4 large moons of Jupiter. -Planets appeared as disks. -Phases of Venus. -Features on the Moon. -Sunspots. |
|
|
Sir Isaac Newton (1640-1720) |
Law of universal gravitation.
Proved that the force of gravity, combined with the tendency of a planet to remain in straight-line motion, results in the elliptical orbits discovered by Kepler. |
|
|
Constellations |
- Configuration of stars named in honor of mythological characters or great heroes. - Today 88 constellations are recognized. - Constellations divide the sky into units, like state boundaries in the US. - The brightest stars in a constellation are identified in order of their brightness by the letters of the Greek alphabet-alpha, beta, etc. |
|
|
Position in the Sky |
Stars appear to be fixed on a spherical shell (celestial sphere) that surround the Earth. |
|
|
Equatorial System of Location |
A coordinate system that divides the celestial sphere. Similar to the latitude-longitude system that's used on Earth's surface. Two Locational Components: - Declination: The angular distance north or south of the celestial equator. - Right Ascension: The angular distance measured eastward along the celestial equator from the position of the vernal equinox. |
|
|
Polaris |
North Star
5 links from the big dipper cup |
|
|
Earth Motions |
2 Primary Motions: Rotation and Revolution. - Precession - Movement w/ the solar sys in dir. of Star Vega - Movement w/ the galaxy w/i the unverse |
|
|
Rotation |
Turning, or spinning, of a body on its axis Two measurements for rotation - Mean Solar Day: the time interval from one noon to the next, about 24 hours. - Sidereal Day: Time it takes for Earth to make one complete rotation (360' w/ respect to a star other than the Sun - 23 hrs, 56 min, and 4 sec) |
|
|
Revolution |
The motion of a body, like a planet or moon, along a path around some point in space. Earth's orbit is elliptical |
|
|
Perihelion |
Earth is closest to the sun. January |
|
|
Aphelion |
Earth is farthest from the sun. July |
|
|
Plane of the Ecliptic |
Imaginary plane that connects Earth's orbit w/ the celestial sphere. |
|
|
Precession |
Wobble
Very slow movement of the Earth.
Direction in which Earth's axis points continually changes. |
|
|
Lunar Phases |
The relative positions of the Sun, Earth, and Moon constantly change.
Lunar phases are a consequence of the motion of the Moon and the sunlight that is reflected from its surface. |
|
|
Synodic Month |
Cycle of the phases. Takes 29 (1/2) days. |
|
|
Sidereal Month |
True period of the Moon's revolution around Earth. Takes 27 (1/3) days. |
|
|
Lunar Motions |
Synodic Month and Sidereal Month - Difference of the 2 days comes from movement of Earth and Sun. Takes more time to get to same exact position. Moon's period of rotation about its axis and its revolution around Earth are the same, 27 (1/3) days. - Causes the same lunar hemisphere to always face Earth. |
|
|
Eclipses |
Simply shadow effects that were first understood by the early Greeks.
Two types of eclipses: Solar and Lunar Eclipse
For any eclipse to take place, the moon must be in the plane of the ecliptic at the time of new- or full-Moon phase. |
|
|
Solar Eclipse |
Moon moves in a line directly btwn Earth and the Sun. Can only occur during the new-Moon phase. |
|
|
Lunar Eclipse |
Moon moves within the shadow of Earth. Only occur during the full-Moon phase. |
|
|
Two Groups of Planets |
Terrestrial (Earth-like) Planets
Jovian (Jupitar-like) Planets |
|
|
Terrestrial Planets |
Mercury through Mars
Small, dense, rocky
Low escape velocities |
|
|
Jovian Planets |
Jupiter thru Neptune
Low density, gaseous, Massive
Thick atmospheres composed of hydrogen, helium, methane, and ammonia.
High escape velocities |
|
|
Mercury |
Innermost and smallest planet, but very dense No atmosphere Cratered high-lands and vast, smooth terrains Revolves quickly, but rotates slowly |
|
|
Venus |
Second to the moon in brightness. Similar to Earth in (size, density, location in solar system) Shrouded in thick clouds: Impenetrable by visible light. Atmosphere is 97% carbon dioxide. Surface atmospheric pressure is 90x that of Earth. Features: 80% of surface is subdued plains that r mantled by volcanic flows. Low density of impact craters. Tetonic deformation must have been active during the recent geologic past. Thousands of volcanic structures. Mapped by radar. |
|
|
Mars |
Called the "Red Planet" Atmosphere: 1% as dense as Earth's. Primarily Carbon Dioxide. Cold polar temperatures (-193' F). Polar caps of water ice, covered by a thin layer of frozen carbon dioxide. Extensive dust storms w/ winds up to 270 km per hr Surface: Many large volcanoes (largest is Mons Olympus). Less-abundant impact craters. Tetonically dead. Several large canyons: some larger than Earth's Grand Canyon, Valles Marineris (largest canyon). Moons: 2 Phobos and Deimos. Thought to be captured asteroids. |
|
|
Jupiter |
Largest planet. At least 28 moons. Very Massive: 2.5 times more massive than combined mass of the planets, satellites, and asteroids. 10 times bigger, it would've been a small star. Rapid rotation: slightly less than 10 hrs. Slightly bulged equatorial region. Banded appearance: Multicolored. Bands r parallel to Jupiter's equator. Generated by wind systems. Great Red Spot: In Southern hemisphere. Counterclockwise rotating cyclonic storm. |
|
|
4 Largest Moons of Jupiter |
Discovered by Galileo - called Galilean satellites
Each has its own character - Callisto: outermost Galilean moon - Europa: smallest Galilean moon - Ganymede: largest Jovian satellite - Io: innermost Galilean moon and is also volcanically active. |
|
|
Saturn |
Similar to Jupiter in its (Atmosphere, composition, internal structure)
Rings: Most prominent feature. Discovered by Galileo in 1610. Complex satellite system. - Composed of small particles (moonlets) that orbit the planet. -Most rings fall into one of two categories based on particle density. -Thought to be debris ejected from moons. - Origen is still debated. |
|
|
Uranus |
Uranus and Neptune are nearly twins
Rotates "on its side"
Rings
Large moons have varied terrains |
|
|
Neptune |
Dynamic Atmosphere - One of the windiest places in the solar system - Great Dark Spot Eight satellites Triton (largest Neptune Moon): Orbit is opposite the direction that all other moons travel (retrograde) |
|
|
New Class of Planets |
Orbit the Sun Not the only objects to occupy their area of space. Pluto is the prototype of this new category Located in the Kuiper belt - a band of icy objects found beyond the orbit of Neptune. Has one moon Sharon. |
