The protective layer of special oxygen molecules in the upper stratosphere that screens out much harmful radiation from the sun is called the ozone layer.

Here's a breakdown:

* Ozone (O3) is a molecule made up of three oxygen atoms.

* Stratosphere: This is the layer of the atmosphere above the troposphere (where we live).

* Harmful radiation: This includes ultraviolet (UV) radiation from the sun, which can damage DNA and cause skin cancer.

The ozone layer absorbs most of the sun's harmful UV radiation, preventing it from reaching the Earth's surface. This vital shield is essential for life on Earth.