Chapter 21

Why would ancient cultures care about the arrangement of the stars and the planets?

-Agriculture: planting and harvesting. -Animal migration. -Myths. -Plagues.

Galileo Galilei (1564-1642).

-Constructed "his" 1st telescope in 1609. Discoveries -4 large moons of Jupiter. -Planets were circular disks not points of light. -Venus has phases like our Moon. -Moon has features (such as water). -Sunspots.

Aristarchus (312-230 B.C.)

-Credited with sun-centered universe (heliocentric view). -Tried to calculate sizes of Sun and Moon but missed the mark. -Did realize hat the Sun was way farther from the Earth than the Moon is. -Lost our to Aristotle's Earth centered view for nearly 2,000 years.

Nicolaus Copernicus (1473-1543).

-Discovered Aristarchus's writings. -Re-established Heliocentric (sun centered) model. -Concluded Earth was a planet. -Supporter Bruno burned at the stake.

Aristotle (384-322 BC) geocentric view.

-Earth is a sphere - curved shadow on Moon. -Sun, Moon and other planets orbited around the Earth.

Seven heavenly bodies - Sun, Moon & 5 visible planets.

-Mercury, Venus, Mars, Jupiter, and Saturn. -Sun, Moon, and other planets orbited around the Earth.

Solar eclipse

-Moon moves in a line directly BETWEEN Earth and the Sun. -Can only occur during the new-Moon phase.

Lunar eclipse

-Moon moves within the Earth's shadow. -Only occurs during the full-Moon phase.

Isaac Newton (1643-1727).

-Three universal laws of motion. -"Newtonian physics". -Universal Law of gravitation. -Invented reflecting telescope. -Calculus.

Johannesburg Kepler (1571-1630).

-Ushered in new astronomy. -Supported Copernicus theory. -Revelation- Mars has an elliptical obit.

Kepler's Laws of Planetary Motion.

1.) Paths of planets around Sun are elliptical. 2.) Law of equal areas (geometrically expresses variation in orbital speed). 3.) Orbital periods of planets and their distance to the Sun are proportional.

Lunar phases

Are a consequence of the motion of the Moon and the sunlight is reflected from its surface.

Constellations

Are patterns of stars named in honor of mythological characters or great heroes. -88 are recognized today. -The brightest stars in a constellation are identified in order of their brightness by the letters of the Greek alphabet.

In the Ptolemaic (Greek) model of the universe, the stars are attached to the __________.

Celestial sphere.

The earliest astronomical records appear to have been made by the ancient Chinese, Egyptians, and Babylonians in order to __________.

Determine when to plant crops or hunt animals based on seasonal changes.

Which of the following statements best describes a geocentric view of the universe?

Earth is a motionless sphere at the center of the universe and the Sun, the Moon, and the planets orbit it.

In the Ptolemaic (Greek) model of the universe, the __________.

Earth was in the center of the universe.

One of the discoveries which led to the modern view of the solar system was that the orbits of the planets are __________.

Ellipses.

T or F? Earth is closest to the Sun in July.

False.

T or F? The distance from Earth to the Sun is used to measure distances in the solar system and is called a light year.

False.

This scientist was the first to use the telescope in astronomy.

Galileo.

Geocentric Universe

Is a view of the universe based on religion and philosophy.

Synodic month

Is the cycle of the Moon thru is phases.

Revolution

Is the motion of a body, such as a planet or Moon, along a path around some point in space. -Earth is closest to the Sun (perihelion) in January. -Earth is farthest from the Sun (aphelion) in July. The plane of the ecliptic is an imaginary plane that connects a planet's orbit with the celestial sphere.

Rotation

Is 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- the time it takes for Earth to make one complete rotation (360 degrees) with respect to a star other than the Sun.

Three laws of planetary motion were discovered by __________.

Johannes Kepler.

Can we see all of the Moon, why?

Moon's period of rotation about its axis AND its revolution around Earth are the same amount of days/time.

A total eclipse of the Sun is only possible at __________.

New moon.

The first modern astronomer to propose a Sun-centered universe was __________.

Nicolaus Copernicus.

Which of the three primary motions of Earth describes how the axial tilt of the planet slowly changes direction every 26,000 years?

Precession.

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.

What are the TWO primary motions of Earth?

Rotation and revolution.

Eclipses

Show effects that were first understood by the early Greeks. -Two different types.

This scientist determined the nature of the forces that kept the planets in their orbits.

Sir Isaac Newton.

Which of these men formulated the Law of Universal Gravitation?

Sir Isaac Newton.

Precession

The Earth wobbles on its six as it rotates. (Like a spinning top toy).

When the Moon is going through its phases, these phases are created by the casting of a shadow. Which celestial body's shadow results in the different phases of the Moon?

The moon.

Sidereal month

True period of the Moon's revolution around Earth.

T or F? Earth is closest to the Sun in January.

True.

T or F? Galileo discovered Jupiter's four largest moons.

True.

T or F? Galileo discovered that the Sun has "blemishes," which we call sunspots.

True.

T or F? The ancient Greeks proposed an Earth-centered view of the universe.

True.

A __________ moon is when the Moon is moving into a position where observers on Earth can see more of the sunlit face.

Waxing.