Observers in ancient Greece noticed that although the stars seemed to move, they stayed in the same position relative to one another. These patterns of stars, called constellations, kept the same shapes from night to night and from year to year. The Greeks thought that Earth was inside a rotating dome called a celestial sphere. Since the word geo is the Greek word for Earth, an Earthcentered explanation is known as a geocentric system. In a geocentric system, Earth is at the center of the revolving planets and stars. About A.D. 140, the Greek astronomer Ptolemy further developed the geocentric model. Like the earlier Greeks, Ptolemy thought Earth was at the center of a system of planets and stars. In Ptolemy’s model, however, the planets moved on small circles that moved on bigger circles. Copernicus was able to work out the arrangement of the known planets and how they move around the sun. A Greek scientist developed the heliocentric system. In a heliocentric system, Earth and the other planets revolve around the sun. In the early 1500s, the Polish astronomer Nicolas Copernicus developed a new model for the motions of the planets. His sun-centered system is also called heliocentric. Helios is Greek for “sun.” Copernicus was about to work out the arrangement of the known planets and how they move around the sun. Later, Galileo used the newly invented telescope to make discoveries that supported the heliocentric model. Copernicus thought that the planets’ orbits were circles. He based his conclusions on observations made by the ancient Greeks. In the late 1500s, Tycho Brahe made more accurate observations of the planets’ orbits. Johannes Kepler analyzed Brahe’s data. Kepler found that the orbit of each planet is an ellipse. An ellipse is an oval shape, which may be elongated or nearly circular. Kepler used the new scientific evidence gathered by Brahe to disprove the long-held belief that the planets moved in perfect circles. Since Galileo’s time, our knowledge of the solar system has increased dramatically. T planets and their moons, and several kinds of smaller objects that revolve around the sun.

Question

An image of the ancient Greek model, Ptolemy's geocentric model, Copernicus's heliocentric model of the solar system is shown

Fill in each blank to complete each statement

answer choices are: ancient Greek, Ptolemy's geocentric, and Copernicus's heliocentric

The sun-centered system of planets developed by Copernicus is an example of an ____ model.

Kepler discovered that the orbit of each planet is an _____, rather than a perfect circle.

An earth-centered system of planets is known as an ____ model.

Answer 1

The sun-centered system of planets developed by Copernicus is an example of a Copernicus's heliocentric model.

Kepler discovered that the orbit of each planet is an ellipse, rather than a perfect circle.

An earth-centered system of planets is known as an Ptolemy's geocentric model.

Answer 2

Would the following changes increase of decrease the gravitational pull between the earth and sun?

the sun doubles in size. increase or decrease
the sun was farther away from earth. increase or decrease
the earth becomes closer to the sun. increase or decrease

Answer 3

Let's analyze each change in terms of how it would affect the gravitational pull between the Earth and the Sun:

1. The sun doubles in size.
   Increase: The gravitational pull would increase because gravitational force is directly proportional to the mass of the objects involved. If the size of the Sun doubles, it would imply an increase in its mass, which would increase the gravitational pull.

2. The sun is farther away from Earth.
   Decrease: The gravitational pull would decrease because gravitational force is inversely proportional to the square of the distance between the two objects. As the distance increases, the gravitational pull weakens.

3. The Earth becomes closer to the Sun.
   Increase: The gravitational pull would increase because, similar to the previous point, gravitational force is inversely proportional to the square of the distance. If Earth is closer to the Sun, the gravitational pull increases.

Answer 4

Order the objects in space from smallest to largest

constellation
star
galaxy
universe
planet
asteroid

Answer 5

Here is the order of the objects in space from smallest to largest:

1. Asteroid: Small rocky bodies orbiting the Sun, generally much smaller than planets.
2. Planet: Larger bodies that orbit stars; for example, Earth orbits the Sun.
3. Star: A massive, luminous ball of gas, primarily hydrogen and helium, undergoing nuclear fusion (e.g., the Sun).
4. Constellation: A group of stars that form a recognizable pattern in the sky, but the distance between the stars can vary greatly.
5. Galaxy: A vast system comprising billions of stars, planets, gas, dust, and dark matter, bound together by gravity (e.g., the Milky Way).
6. Universe: The largest scale, encompassing all galaxies, stars, planets, and all forms of matter and energy.

So, the order is: Asteroid → Planet → Star → Constellation → Galaxy → Universe.

Answer 6

categorize galazies as spiral, elliptical and irregular. You may use each response more than once.

80% of the galaxies in the universe

the milky way galaxy

andromeda galaxy, our closest neighbor

Answer 7

Here is how to categorize the galaxies based on the types you provided:

1. 80% of the galaxies in the universe: Elliptical (most galaxies are actually elliptical in shape)

2. The Milky Way Galaxy: Spiral (the Milky Way is classified as a barred spiral galaxy)

3. Andromeda Galaxy, our closest neighbor: Spiral (the Andromeda Galaxy is also a spiral galaxy)

So, the categorizations are:

• 80% of the galaxies in the universe: Elliptical
• The Milky Way Galaxy: Spiral
• Andromeda Galaxy, our closest neighbor: Spiral