The document discusses the sun's positive and negative effects on humans. Positively, the sun provides warmth, energy through photosynthesis, boosts serotonin levels and immunity. However, ultraviolet radiation from the sun can cause skin cancer, sunburns, weaken the immune system, lead to heat stroke and damage eyes and skin over time. While the sun has benefits, prolonged unprotected exposure to its UV rays poses health risks like skin cancer, so protection is recommended to harness its energy safely.

1. Sun – our friend or foe?
By Dorotėja Sirvydytė and Aistė Šutaitė
Kaunas “Vyturys” catholic secondary school.

2. About Sun
 Sun is the star at the centre
of the solar system. It’s so
big, that 1.300.000 Earths
could fit in it!
 Sun provides us with
warmth and energy.
However, although it is the
reason life exists, it can
also be very dangerous.

3. Positive effects of the
sun

4. Sunlight = life
 Sun helps plants prepare
food through
photosynthesis, so if
there would be no
sunlight, there would be a
collapse in the food chain
of every habitat.

5. Sunshine and happiness
 Sunshine boosts levels
of serotonin – the body’s
natural happy hormone.
That’s why we tend to
feel happier when the
sun shines.

6. Sunshine boosts immune system
 Sunlight produces vitamin
D and encourages the
production of white cells,
which help to boost your
immune system and fight
infection.

7. Negative effects of the
sun

8. Ultraviolet radiation
 Ultraviolet (UV) rays are
invisible waves that are part
of the energy that comes
from the sun.
 In spite of all their positive
uses, UV rays remain very
harmful for anyone who
spends a large amount of
time in the sun without
proper protection.

9. Negative effects of ultraviolet
rays
 Skin cancer
 Skin cancer is caused
by the exposure to the
Sun. Research shows
that as many as 90
percent of skin cancers
are due to UV
radiation.

10. Negative effects of ultraviolet
rays
 Causes sunburn.
 This damage to the skin is caused by the
absorption of energy from UV rays.

11. Degrees of sunburn

12. Negative effects of ultraviolet
rays
 Damages immune system.
 Scientists believe that
sunburn can change the
distribution and function of
disease-fighting white blood
cells in humans for up to 24
hours after exposure to the
Sun.

13. Negative effects of ultraviolet
rays
 May cause heat Stroke.
 This is very dangerous because
it can kill you. A good chance to
experience heath stroke is on a
hot summer day when you aren’t
drinking enough water or
covering your head with
protection.

14. Negative effects of ultraviolet
rays
 Damages eyes.
 Prolonged exposure to UV rays damages the
tissues of eyes and can cause a burning of the eye
surface, called photokeratitis.

15. Negative effects of ultraviolet
rays
 Ages skin.
 UV rays speeds up the
aging of skin, since the UV
radiation destroys various
tissues beneath the top
layer of the skin.

16. Conclusion
According to the results of the scientists, we can
affirm, that the Sun is our ally. Even though, the man
knows the negative impact of the Sun on us, he can
adopt the Sun’s energy for positive purposes.

17. Thank you and have a sunny day! 