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Ep 2: WT-SPF is Up With My Sun?!

  • Writer: Nat
    Nat
  • Sep 15
  • 4 min read

Updated: Nov 29

The Sun is both our life source and our biggest enemy. Without it, Earth would be a frozen rock. With it, we get warmth, light, energy, and a little serotonin boost on a sunny day. But the same star that keeps us alive is constantly bombarding us with radiation that can damage our skin on a microscopic level. To understand why sunscreen matters, we first need to go way way back - to the birth of the Sun itself, the beautiful (and spooky) power of nuclear fusion, and the invisible waves of energy it sends across space to reach us.


Let me tell you about my Sun


Billions of years ago, a massive cloud of gas and dust started swirling in space. Gravity pulled it together, spinning faster until it flattened into a disk. At the center, pressure and heat built up until it became hot enough for Nuclear Fusion. That’s when a baby star - our Sun - was born.


What is Nuclear Fusion?



To understand that, let’s start with the periodic table. The world is built from atoms—tiny particles made of protons (positive), neutrons (neutral), and electrons (negative). Protons and neutrons live in the nucleus (center of the atom), while electrons zoom around the outside in organized shells. The number of protons defines the atom. Neutrons can vary, which can lead to different versions of the same element, called isotopes.


Source: Nat's Canva skills
Source: Nat's Canva skills

Hydrogen, the simplest atom, has one proton and one electron. Most hydrogen atoms have no neutrons, but there are rare isotopes: Deuterium (one neutron) and Tritium (two neutrons). These isotopes played a starring role in creating our Sun.


Fusion occurs when light atoms smash together to form heavier ones, releasing enormous amounts of energy. Inside our Sun, Deuterium and Tritium collide at millions of degrees. For a brief instant, they form a nucleus with two protons and three neutrons; then a neutron is ejected, leaving behind Helium. This process releases so much energy that it fuels more fusion reactions, creating a chain reaction.


All of this is so hot (like, truly SO hot) that matter turns into plasma, which is basically a soup of charged particles where electrons are stripped away from protons. Plasma moves like waves, releasing energy across the electromagnetic spectrum.


The Sun’s Waves


The electromagnetic spectrum includes a whole range of waves, sorted by wavelength and energy:


  • Gamma rays: extremely high energy, capable of splitting atoms.

  • X-rays: useful in medicine but blocked by Earth’s atmosphere.

  • Ultraviolet (UV): reaches Earth, split into UVC (blocked by ozone), UVB (causes sunburn and tanning), and UVA (penetrates deeper, causing aging and immune suppression).

  • Visible light: the rainbow of colors we can see, from blue (higher energy) to red (lower energy).

  • Infrared: felt as heat - like the warmth you notice when stepping out of the shade.

  • Microwaves and Radio waves: lower energy, used in technology like communication and cooking.


So why is the sun dangerous for our skin?


For skin health, the UV region is the most important. Unlike visible light, which we perceive as color, or infrared, which we feel as heat, UV rays are invisible and carry enough energy to damage DNA. That damage can look like sunburn in the short term, or premature aging and cancer over time.


This is where sunscreen comes in. Sunscreens are designed to absorb or scatter UV rays before they can harm your cells. But how well they work is usually described by SPF, or Sun Protection Factor. SPF measures how well a product protects against UVB rays, which are the ones that burn your skin. For example, SPF 30 means your skin would take 30 times longer to redden than it would without protection.


That sounds simple enough, but here’s the catch. SPF only covers half the story. There’s another category of UV light, called UVA, that doesn’t cause immediate redness, but it can age your skin, damage collagen, and play a role in cancer. To really understand why sunscreen is essential, and why SPF alone isn’t enough, we need to dive deeper into UVA and UVB.


In our episode 2 weeks from now, we’ll look closer to the ultraviolet spectrum itself and uncover the real difference between UVA and UVB; why one burns, the other ages, and why we need to keep ourselves protected from both.


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