Page 34 - How It Works - Book Of Amazing Answers To Curious Questions, Volume 05-15

Why is it

dangerous to

look directly at

the Sun?

he Sun’s light contains far more energy
Tthan our eyes can safely absorb, and it
can damage the eye’s delicate structures
within seconds. Staring directly at the Sun
for a few seconds typically causes
How does dry photokeratitis, a condition similar to
sunburn, which leads the cornea to become

cleaning work? cracked and inflamed. Though it is very
painful, patients usually recover fully. Longer
exposure can damage the retina, causing
vision to become blurry or discoloured for
several months. Eyesight may never return
to normal. Damage to the macula, a portion
of the retina used for detailed vision, can
How do chameleons result in permanent loss of visual acuity.

camouflage themselves?

ertain species of chameleon have layers talents to attract a mate rather than to hide
Cof cells called chromatophores, which from predators. For most species of
contain different-coloured pigment granules; chameleon, camouflage works in a similar

by moving these granules around, they are way to camouflage in other animals, and
able to control their colour. However, this they have evolved over time to blend in with
technique is more commonly used as a their surroundings. For example, the mottled
method to signal emotions than for colour and spiky shape of the brown leaf

camouflage, and the species with the best chameleon make it almost invisible among
colour-changing abilities tend to use their dead leaves.

Why do Why don’t

geysers spurt spiders stick to

out hot water? their own webs?

geyser is a natural vent in the Earth’s ot all the threads on a spiderweb are
A surface, which intermittently spurts out Nsticky. The spokes of the web pattern
tall columns of hot water and steam. They are made from a dry, structural silk and
form in areas that have volcanic activity. spiders mostly walk on these threads as
What makes a geyser such a unique and they move around the web. But they also
incredible phenomenon is that it requires at need to be able to handle the sticky spiral
least three very specific conditions to form: threads when building and repairing the

a water supply that refills the geyser after an web, without getting stuck themselves.

eruption; a heat source, which is normally They can do this because their legs are
hot rocks that heat the water; and a covered with stiff bristles that minimise
pressure-tight plumbing system to store the the surface area in contact with the sticky
water as it is heated. As more hot water droplets. They also have an oily substance
flows through the narrow pipes of the that repels the adhesive and acts as a

plumbing system, intense pressure causes it non-stick coating.
to erupt.

34 How It Works