Which of these common characteristics do only the outer planets share?

Which of these planets is mostly gas?

_____ keeps planets away from the sun, while _____ pulls planets toward the sun.

Proxima Centauri is the next closest star to Earth, after the Sun, and lies 4.22 light years away. This

means that when we go out on a clear night and look up at Proxima Centauri, we are seeing light that

left that star ______.

Copernicus thought the orbits of the planets were circular, but __________ showed them to be elliptical.

Later work by ______ resulted in the development of the _________ model of the solar system, marking

the beginning of modern astronomy.

All of the known dwarf planets except Ceres orbit in the ___.

If the mass of the Earth suddenly and magically increased by 50%, what would happen to the Moon’s orbit?

The ____ of two objects and the distances between them determine the gravitational attraction between the objects.

The inner planets are ____ and have ____ surfaces.

All of the outer planets have many ____, which range in number from 13 to more than 60.

All of the gas giants’ atmospheres are made up primarily of helium and ____.

When a meteoroid enters Earth’s atmosphere, it produces a streak of light called a(n) _____.