6.5 Galaxies [Mastery check]

What is the name of our galaxy?

Answer explanation

Milky Way

What are the components of a galaxy?

Answer explanation

Stellar dust, gas, stars, planets or solar systems.

What is the name of the force that binds all the celestial bodies within a galaxy together?

Answer explanation

Gravity

What are the three different shapes of galaxies?

Answer explanation

Spiral, elliptical, irregular.

Describe the shape of the galaxy where we live.

Answer explanation

spiral

Name the most common type of object that gives out its own light in a galaxy.

Answer explanation

Star

What is the name of the star closest to Earth in our Galaxy?

Answer explanation

Sun

How many stars are there in our galaxy?

• about 100 000 000

• about 250 000 000

• about 100 000 000 000

• about 250 000 000 000

What is the term for the entirety of space and everything in it?

Answer explanation

Universe

Scientists have counted the galaxies in one part of space. The scientists then multiplied this number up to estimate the number of galaxies in the Universe. Estimates such as this may not be accurate because (pick 2)

• there could be more or fewer galaxies in the part of space that the scientists counted compared with the rest of the Universe.

• the scientists may not know the total volume of the Universe accurately.

• the spacing between the galaxies are uniform.

• some galaxies do not have a definite shape.