Planets don't emit their own light. We see them because sunlight reflects off their surfaces.

Here's why:

* The Sun is the primary source of light in our solar system. It emits a vast amount of light and heat.

* Planets are celestial bodies that orbit the Sun. They don't generate their own light.

* When sunlight strikes a planet, it interacts with the surface. Some light is absorbed, and some is reflected back into space.

* The reflected sunlight is what allows us to see the planets. The intensity and color of the reflected light depend on the composition and properties of the planet's surface.

This is similar to how you can see a ball in a dark room by shining a flashlight on it. The flashlight acts like the Sun, and the ball reflects the light.