The Sun & UV Rays
The sun gives us light, warmth, and life on Earth — and it also produces invisible ultraviolet (UV) rays that can damage skin. This page covers what UV is, the three types, and how it affects your body.
What the sun is
- The sun is a giant star made mostly of two gases: hydrogen and helium.
- It is over 4.5 billion years old.
- Its energy comes from nuclear fusion — hydrogen atoms fuse into helium, releasing enormous amounts of energy.
How the sun's energy reaches us
Solar energy travels to Earth in several forms. The three most important to know:
- Visible light — the part of the spectrum your eyes can see.
- Infrared — what you feel as warmth on your skin.
- Ultraviolet (UV) rays — invisible, higher-energy radiation. This is the part that affects skin health.
What UV rays are
Ultraviolet means "beyond violet" — radiation at wavelengths just shorter than visible violet light, which the human eye cannot detect.
There are three categories:
- UVA — penetrates deeply and contributes to premature aging (wrinkles, age spots) and long-term skin damage.
- UVB — the main cause of sunburn and a primary driver of most skin cancers.
- UVC — the most energetic, but absorbed by the atmosphere's ozone layer before reaching the surface.
How UV affects skin
Your skin is built from cells, and inside every cell is DNA — the instructions that tell your body how to grow and function.
Excess UV exposure can damage that DNA. Over time, this can lead to:
- Sunburn (acute UVB damage).
- Premature aging — wrinkles, age spots, loss of elasticity.
- Skin cancer — sometimes years or decades after the initial exposure.
Protection today reduces the cumulative damage that drives skin cancer risk later in life.
Why kids face higher risk
- Children's skin is thinner and more sensitive than adult skin.
- Sunburns during childhood significantly increase melanoma risk later in life.
- Roughly 80% of a person's lifetime UV exposure occurs before age 18, which is why early habits matter so much.
The protective steps are straightforward: sunscreen, UPF clothing, hats, sunglasses, and shade. Continue to Sun Safety Habits for specifics.