How have observations of the sky enabled humans to explore and travel? These are the questions: How have observations of the sky enabled humans...

Diana, you can only ask one question at a time. I will
tackle the first part of your question here.

Observations
of the sky allowed explorers to mark the passage of time both in hours and through the
months of the year. Early astronomers also realized that the night sky does not look the
same from different places on the Earth. This led to the realization that careful
astronomical observation would make it possible to figure out where on the surface of
the Earth you were. This allowed for travelers to set out on an exploration knowing that
they would be able to find their way back home.

Another
important piece of information that astronomy imparted was the idea that the Earth was
round. The ancient Greeks not only knew the href="http://www-istp.gsfc.nasa.gov/stargaze/Scolumb.htm">Earth was round,
they also estimated its radius pretty accurately. Having this information increased the
number of explorers, because they did not, contrary to popular belief, fear falling "off
the edge" of the planet.