How Perceiving Earth as a Sphere Works

Is there any way that people could know the world is sphere while standing on the earth? Learn more about perceiving earth as a sphere in this HowStuffWorks podcast.

Learn more about your ad-choices at https://www.iheartpodcastnetwork.com

See omnystudio.com/listener for privacy information.

Episode Transcript

Speaker 1 (00:00):
Welcome to brain Stuff from how stuff works dot com
where smart Happens. Hi. I'm Marshall Brain with today's question.
Is there any way that people could know that the
world is a sphere while standing on the Earth? In
other words, is the only way to know that the
world is a sphere to be up in space looking

(00:23):
down on that sphere? Or could you somehow figure this
out while standing on a planet that appears at least
superficiently to be flat. If you didn't know that the
Earth is a sphere, there are two common observations you
could use to convince yourself that it is. The first
common observation is the shape of the moon. You see

(00:44):
the moon up there every night, and the face of
the full moon is circular. That might lead you to
believe that it's a sphere rather than a big, round,
flat disk. By extrapolation, you could assume that the Earth
is a sphere also. But there's a second way that's
more convincing. You would look at how objects in the

(01:05):
distance disappear as they get further away. For example, if
you had a hundred foot tall sailing ship that's fifteen
miles away, it's not visible even if you try to
see it with the telescope. That's because it's blocked by
the curvature of the sphere. As the ship approaches it rises.

(01:26):
First the tip of the mast is visible, then more
and more of the ship comes into view as the
ship gets closer. Anyone looking at ships at sea would
notice this and they would be able to tell that
the Earth is a sphere. Do you have any ideas
or suggestions for this podcast? If so, please send me

(01:47):
an email at podcast at how stuff works dot com.
For more on this and thousands of other topics, go
to how stuff works dot com.