The density of gas in a collapsing interstellar cloud is low at first, but ____________________draws matter together until it is concentrated enough to form a star and possibly planets.

Where is the concentration of matter the densest as an interstellar cloud collapses?

The Sun formed when the dense concentration of gas and dust at the center of a rotating disk reached a temperature and pressure high enough to fuse hydrogen into

The rotating disk surrounding the young Sun became our

Space objects built of solid particles that can form planets through collisions and mergers are called

Theories of the origin of the solar system rely on direct ___________________ and data from probes.

Select all that apply

Which are true about the terrestrial planets?

Early astronomers thought that the Sun, planets, and stars orbited a stationary Earth . This is known as the __________________ model of the solar system.

Which are space objects built of solid particles that can form planets through collisions and mergers?

The apparent backward movement of a planet is called

In the heliocentric model, what is at the center of the solar system?

The gas giants formed through the merging of icy _________________ that contained mostly lighter elements.

Select all that apply

Which factors determine the force of gravitation between two bodies?

Early astronomers thought that all objects in space orbited Earth. What is the name for this early model of the solar system?

Copernicus suggested that Earth and all the other planets orbit the Sun . This is known as the ___________________ model of the solar system.