What makes the moon yellow?

Sometimes the Moon looks yellow when its low in the sky. This is for the same reason that the Sun looks red at sunset.

The Earth's atmosphere "scatters" incoming light. Blue light is scattered more than yellow or red light.

The effect is much greater when the Moon or Sun is near the horizon, because the light has to travel through more air before we see it.

So, the Moon can often look yellow when it's low in the sky.