http://www.howitworksdaily.com How It Works 089
Teresa Warren
n The Global Positioning System uses a net work
of satellites that beam radio signals to Earth.
These signals contain super accurate time
information. Your receiver, such as your
smartphone, can figure out how far you’ve
moved in relation to these satellites by
comparing the time of the new signal to the one
you received previously.
Because the system was developed by the US
A ir Force, it is paid for by A merican taxpayers,
but free for ever yone else. MSWhat is GPS
and how is
it free?
©Getty
Paige Morgan
n The Moon is illuminated by the Sun. To see a full Moon, the Sun must
be immediately behind us, which only happens at night. But when the
Moon is a partially illuminated crescent, the Sun can be in the sk y at the
same time. AMWhy can I sometimes see
the Moon during the day?
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futurenet.comBecky Lee
n A round 40 per cent of birds are
regular migrants. It’s a sur v ival
tactic. Cold weather in Europe
causes insect and rodent
populations to plummet, so it’s
smart to seek out a warm climate
crawling w ith prey. A few northern
species v isit the UK in w inter
because the weather is fairly mildcompared to their A rctic origins.
Sometimes huge flocks of birds fly
to a new destination for a
temporar y feeding fren zy when
their food source at home runs low.
A few species flee to remote spots
w ith few predators before moulting
their worn-out flight feathers. They
return home once they are able to
fly again. AGWhy do some birds
migrate to other countries?
Arctic terns can travel 20,000
kilometres in just six months.
That’s halfway around the worldA network of satellites
enables us to find our
location anywhere on
Earth using GPS© United States Government