Page 115 - How It Works - Book Of Amazing Answers To Curious Questions, Volume 05-15

Space

Why can’t we feel the How do we know

Earth’s spinning? dark matter exists
if we can’t see it?

ou can! The Earth’s rotation causes the Coriolis effect, which
Ygenerates a centrifugal force deflects the wind in opposite
pulling upward, acting to partially directions in the northern and obody has seen dark matter, but astronomers
balance out the force of gravity southern hemispheres. Westerly or Ncan detect its presence from the gravitational
pulling us down, but it’s very subtle. southwesterly winds in Britain are pull it exerts on other objects, such as stars or
At the equator, you weigh 0.346 per due to the Coriolis effect, so you galaxies. Dark matter has mass but does not emit or
cent less than at the poles. That’s a could say you feel the Earth spinning absorb electromagnetic radiation, so it is invisible to
difference of only about 250g when the wind in your face is from telescopes. But the movements of distant galaxies
(8.8oz). The Earth’s rotation also the west or southwest. suggest that something with a very large mass is
altering their paths by exerting a gravitational force on
them. We know relatively little about dark matter, but
some believe it could be made up of a new type of
subatomic particle called a WIMP (weakly interacting
massive particle), although no experiment has yet
proven that these exist.

How long could we survive if the Sun died?

f the Sun suddenly died, Earth would be including humans could survive for a while,
I transformed into a cold, dark, lifeless planet in a although their food would soon run out too. From
matter of weeks or months. Without the Sun’s then onwards, how long humans could survive for
energy, no photosynthesis could occur, spelling the would depend on their ingenuity and technology. A
end for all plant life within weeks. The Earth’s nuclear fusion reactor for instance, might enable us
surface temperature would drop off, reaching to sustain ourselves. However, in reality, the Sun’s
temperatures below freezing within a few days. death will occur over millions of years and our star
With no plants around, plant-eating species would will first increase in intensity and dry out the
be next to go as they exhausted food supplies. If planet’s water, ending all life on Earth long before
they could endure the cold, meat-eating species its own death.

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