You can't see stars when facing the sun because the sun's light is far too bright.

Here's why:

* Sunlight overwhelms starlight: The sun is incredibly bright, emitting a vast amount of light that washes out the much fainter light from distant stars.

* Atmospheric scattering: The Earth's atmosphere scatters sunlight, making the sky appear blue during the day. This scattered light further obscures the stars.

You can only see stars at night when the sun is below the horizon, and the sky is dark enough for the faint starlight to become visible.