Birth of Modern Astronomy

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What is Newton's first law of motion?

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Newton's first law of motion (the law of inertia) states that an object at rest or moving will continue to do so unless acted upon by an external force.

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What did Kepler do after inheriting Brahe's planetary data?

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Kepler spent over seven years mathematically crunching the data, resulting in Kepler's laws of planetary motion.

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What does Kepler's third law state?

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Kepler's third law states that the square of a planet’s orbital period (P) is equal to the cube of the semi-major axis (a) of its orbit: P² = a³.

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How did Newton explain the motion of planets?

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Newton used his three laws of motion and the law of gravity to explain how and why the planets moved according to Kepler's laws.

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Why was Galileo criticized for his observations?

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Galileo received criticism because his findings went against the strict teachings of the Church.

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What is the law of gravity?

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The law of gravity states that every mass attracts every other mass in the universe, and the force of attraction is proportional to the product of their masses and inversely proportional to the square of the distance between them.

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What are Kepler's laws of planetary motion?

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Kepler's laws consist of three laws: 1) Planets move in elliptical orbits with the Sun at one focus. 2) A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time. 3) The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit.

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What is inertia?

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Inertia is the property of an object to resist changes in its state of motion; an object at rest stays at rest, and an object in motion stays in motion unless acted upon by a force.

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What is an astronomical unit (A.U.)?

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An astronomical unit (A.U.) is a standard unit of measurement used in astronomy, defined as the average distance from the Earth to the Sun, approximately 93 million miles or 150 million kilometers.

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What did Galileo use to support his theories?

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Galileo used a telescope to make observations of celestial bodies, which provided evidence for his theories about the heliocentric model of the solar system.