Second Quiz Flashcards
What is Astronomy?
The science that studies the universe
What was scientist Eratosthenes known for?
Used angles of the noonday sun to establish the size of the earth
What did the geocentric Model show?
All planets orbit around the earth
What did the Heliocentric Model show?
Earth and the other planets orbit the sun
What did the Ptolemaic system show?
The universe & planets
What is the Retrograde motion?
The westward motion of the planets with respect to the stars
Who is Nicolaus Copernicus?
Certified that earth is a planet and model with sun in center
Who is Tycho Brahe?
Built instruments to measure the locations of planets such as Mars
Who discovered the three laws?
Johannes Kepler
What are the three laws?
- Orbits of the planets are elliptical
- Planets revolve around the sun at varying speed
- Relationship between planet’s orbital period and distance to sun
What is an ellipse?
An oval-shaped path
What is an astronomical unit (AU)?
The average distance between the earth & sun; 150 million km
Who is Galileo Galilei?
His descriptions of the behavior of moving objects
What did Galilei develop?
The telescope
What were Galiei discoveries?
- Four moons orbit Jupiter
- Planets are circular disks, not just points of light
- Venus has phases just like the moon
- The moon’s surface is not smooth
- The sun has sun sports or dark regions
Who is Sir Issac Newton?
The first to formulate and test the law of gravitation
Two key points of Universal Gravitation
- Gravitational force decreases with distance
- The greater the mass of an object, the greater is its gravitational force
What are the two main motions of Earth?
Rotation and revolution
What is the third motion called?
Precession and is a very slow motion of Earth’s axis
What is rotation?
The turning, or spinning, of a body on it’s axis (1,000 MPH)
What are the two measurements for rotation?
Mean solar day and Sidereal day
Mean Solar day measurement
From one noon to the next (24 hours)
Sidereal day
The time it takes for Earth to make one complete rotation (360)
How long does it take for earth to make one rotation and have the stars lined up in the same?
23 hours and 56 minutes
What is revolution?
The motion of a body, such as a planet or moon, along a path around some point in space
What is Perihelion?
The time in January when Earth is closest to the sun
What is Aphelion?
The time in July when Earth is farthest from the sun
What is precession?
Traces out a cone over a period of 26,000 years
What is perigee?
The point at which the moon is closest to Earth
What is Apogee?
The point at which the moon is farthest from Earth
What is the synodic month?
The cycle of the moon phases 29 1/2 days
What is the sidereal month?
The true period of the moon’s revolution around earth 27 1/3 days
When did solar eclipses occur?
The moon moves in a line directly between Earth and the sun, casting a shadow on Earth
When do Lunar eclipses occur?
When the moon passes through Earth’s shadow
What is a crater?
The depression at the summit of a volcano or a depression produced by a meteorite impact
What are rays?
A system of bright, elongated streaks
What are highlands?
Densely pitted, light-colored areas
What is Maria?
Ancient beds of basaltic lava, originated when asteroids punctured the surface and led to magma bleed out
What is a rille?
A long channel associated with lunar Maria and is similar to a valley or trench
What is the lunar regolith?
A thin, gray layer on the surface of the moon, consisting of loosely compacted fragmented material
