Question

the electromagnetic radiation from distant stars and galaxies reaches earth through the vacuum of space. what explains how this occurs?
electromagnetic waves reflect off of planets’ atmospheres to reach earth.
electromagnetic waves move quickly enough to travel through space without a medium.
electromagnetic waves do not require a medium to travel through space.
electromagnetic waves vibrate so quickly that they create their own medium through which they travel.

Explanation:

To determine the correct answer, we analyze the properties of electromagnetic waves. Electromagnetic waves (like light) differ from mechanical waves (e.g., sound) in that they do not need a medium (like air, water, or matter) to propagate. Space is a vacuum (no medium), so the key is identifying the option that correctly states this property.

• The first option is incorrect because reflection off planets’ atmospheres isn’t how radiation travels from distant stars/galaxies through space.
• The second option is incorrect; speed isn’t the reason—electromagnetic waves don’t need a medium at all, regardless of speed.
• The third option is correct: Electromagnetic waves do not require a medium to travel through space. This matches their fundamental property (they consist of oscillating electric and magnetic fields that can propagate in a vacuum).
• The fourth option is incorrect; electromagnetic waves do not create a medium—they propagate without one.

Answer:

The correct option is: Electromagnetic waves do not require a medium to travel through space.