Modern Astronomy

axial precession

A very slow motion of Earth's axis that requires 26,000 years to complete is called ________.

precession

A very slow motion of Earth's axis that requires 26,000 years to complete is called ________.

seven

According to the Ptolemaic (Greek) model of the universe, how many "heavenly" bodies could be observed wandering along the background of stars?

perturbation

Any variance in the orbit of a planet from its predicted path is called a(n) ________.

perturbation

Any variance in the orbit of a planet from its predicted path is referred to as ________.

January

Earth is closest to the Sun in the month of ________.

the two moons of Mars

Galileo observed several features using the telescope. Which one of the following did he NOT discover? sunspots Jupiter's four largest moons phases of Venus the two moons of Mars

Earth was in the center of the universe

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

celestial sphere

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

epicycles, deferents

In the Ptolemaic system, planets orbited in small circles called ________ while revolving along large circles called ________.

elliptical

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

ellipses

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

constellations

Patterns or configurations of stars named in honor of mythological characters are called ________.

Ptolemy

The Earth-centered system of the universe that was accepted for nearly seventeen centuries was presented in a treatise called the Almagest that was written by ________.

Sir Isaac Newton

The Law of Universal Gravitation was formulated by ________.

sidereal

The ________ day is the time it takes for Earth to make one complete rotation with respect to a star other than our Sun.

vernal equinox

The ________ is at the point in the sky where the Sun crosses the celestial equator at the onset of spring.

declination

The angular distance north or south of the celestial equator is called ________.

ecliptic

The apparent path of the Sun upon the celestial sphere is called the ________.

retrograde motion

The apparent westward "drift" of the planets compared to the background stars is called ________.

retrograde

The apparent westward drift of the planets as compared to the background stars is called ________ motion.

retrograde motion

The apparent westward drift of the planets as compared to the background stars is called ________.

astronomical

The average distance from Earth to the Sun is called the ________ unit.

Zodiac

The belt of constellations through which all the planets move is called the ________.

zodiac

The belt of constellations through which all the planets move is called the ________.

Nicolaus Copernicus

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

Eratosthenes

The first successful attempt to establish the size of Earth is credited to ________.

Sir Isaac Newton

The law of universal gravitation was formulated by ________.

two weeks

The length of daylight on the Moon is about ________.

synodic

The period of time required for the Moon to complete a cycle of phases is called the ________ month.

inertia, gravity

The planets stay in orbit around the Sun because of a balance between ________ and ________.

ecliptic

The planets, Moon, and the Sun lie along nearly the same plane and therefore move along the same region of the sky that is called the ________.

heliocentric

The proposal that contends that the Sun is in the center of the universe is called the ________ view.

geocentric

The proposal that suggests that Earth is in the center of the universe is called the ________ view.

Johannes Kepler

The true shape of the planetary orbits was discovered by ________.

rotation, revolution

The two primary motions of the Earth are ________ and ________.

Sir Isaac Newton

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

Galileo

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

Galileo

This scientist wrote a book that compared the Earth-centered system with the Sun-centered system entitled Dialogue of the Great World Systems.

Johannes Kepler

Three laws of planetary motion were discovered by ________.

perihelion

When Earth is closest to the Sun, its location is referred to as the ________ position.

aphelion

When Earth is farthest from the Sun, its location is referred to as the ________ position.

Johannes Kepler

Which astronomer developed the three laws of planetary motion?

Sir Isaac Newton

Which of these men formulated the Law of Universal Gravitation?

Nicolaus Copernicus

Who wrote the book entitled Of the Revolutions of Celestial Spheres (De Revolutionibus)?

stellar parallax

apparent shift in the position of a nearby star when viewed from extreme points in Earth's orbit six months apart is called ________.