CHAPTER 10 SCiENCE

Asterism

A peculiar shape formed from stars.

Astrolabe

An instrument that helps to locate and predict the position of the Sun, Moon, and stars.

Constellation

A small group of stars that form a remarkable pattern within a constellation.

Constellation circumpolar

A constellation that never disappears below the horizon.

Seasonal constellation

A constellation that lies on the ecliptic and is not visible for a certain part of the year.

Celestial body

A natural object in space, for example a planet, a moon, an asteroid, a comet or a star.

Ecliptic

The path that the Sun follows across the sky, day after day.

Ellipse

A closed curve which has two foci and of which each point is such that the sum of its distances to the foci is constant.

Epicycle

Ptolemy's explanation is that the planets make small circles in their orbit around the Earth.

Geocentric

Refers to a model of the Universe where the Earth is at the center.

Heliocentric

Refers to a model of the Universe where the Sun is at the center.

Astronomical telescope

An optical instrument equipped with lenses that focus light in order to magnify images.

Planet

A celestial body that orbits the Sun in its own orbit.

Retrograde motion

The apparent change of direction of a planet whose path in the sky forms an "S" or a loop.

Orbit

The regular trajectory of a celestial body in space.

If we look towards the south, the stars seem to move from ____ to ____.

east, west

If we look towards the north, the stars seem to rotate slowly around the ____.

North Star

The sun rises at ____ and sets at ____.

East, west

The Earth makes one ____ on its axis every 24 hours and one ____ around the Sun in 365.25 days.

rotation, revolution

The Earth rotates on its axis from ____ to ____.

West, east

The Moon completes one revolution around the Earth in ____ days.

27

This astronomer discovered the retrograde motion of Mars and conceived the idea of epicycles to support the geocentric model.

Ptolemy

This astronomer mathematically demonstrated that it is the gravitational force of the Sun that keeps the planets in orbit and that this force is exerted beyond the celestial bodies.

Newton

He believed that the Universe is geocentric because the shape of the constellations does not change.

Aristotle

He used a telescope to demonstrate that the Sun is at the center of the solar system.

Galileo

He proposed the idea of a heliocentric model of the Universe where the Earth rotates on its axis every day and revolves around the Sun in one year.

Copernic

He defended the heliocentric model by mathematically describing the orbit of the planets and celestial bodies around the Sun in ellipses.

Kepler