Question: Why do we need the sun to survive if we have radiators to give us heat?

Anna Kutner answered on 19 Jun 2015:

There is more to Sun than just giving off heat and warming the planet and us.

The UV radiation passing through the Earth’s atmosphere is readily used by plants, animal and humans for a variety of purposes. For example, plants use it to synthesise food through a process called photosynthesis.

Some animals use UV radiation from celestial objects (not only the Sun) in navigation or to locate ripe fruits, flowers and seeds which stand out from their surrounding on an UV spectrum.

Humans use UV radiation to treat various skin conditions and, most importantly, to produce vitamin D which helps strengthen bones, muscles and the body’s immune system.

And finally, let’s not forget that sunlight improves our mood. I’m always cheerful when it’s a lovely, sunny day 🙂