What Earth Objects are Visible from Space?

Thanks to Jolene at From Quarks to Quasars

It’s a myth that has persisted for years: the Great Wall of China is the only man-made object that you can see from space. Or even worse, that the Great Wall is the only feature that you can see from the Moon without assistance.

Even if you haven’t heard this myth, I’m sure you’ve often wondered what the Earth looks like from a distance. If neither of these things is true….well then, you should probably get out more.

Let’s tackle the more unbelievable statement first—seeing the Great Wall from the Moon. In fact, seeing the Great Wall from the Moon’s surface would be the same as seeing a human hair from 2 miles away (3.2 km). Unless you have a high-powered telescope, or eyesight that is out of this world,* you’re not going to be able to see such a tiny object.

Given the average distance of the Moon, some 238,000 miles from the Earth (383,000 km), a feature on our planet would have to be roughly 70 miles across (113 km) for the unaided human eye to be able to discern it from the surrounding landscape. At its widest, The Great Wall is a mere 30 feet (9.1m). So it’s not even close.

When asked what features are visible from the Moon, Apollo 12 astronaut Alan Bean stated, “The only thing you can see from the Moon is a beautiful sphere, mostly white, some blue and patches of yellow, and every once in a while some green vegetation. No man-made object is visible at this scale.”

But what about the edge of space? What can the human eye see from this distance? For the sake of argument, we will use the International Space Station as an example. The ISS orbits at about 250miles (402km). That’s a lot closer than the 238,000 miles to the Moon. However, it is almost entirely impossible for the unaided eye to see the Great Wall of China even from this distance. Some scientists have argued that, if the conditions were *absolutely* perfect, then it would be theoretically possible. However, most scientists have rejected this notion, as it would require a visual acuity more than 5 times that of the average human eye. True, a few astronauts have said that they thought they could see the Great Wall, but most state that they couldn’t see it at all (not even a little bit).

However, there are other man-made objects that can be readily seen from the International Space Station: the pyramids at Giza, airports, dams, cities, the Toyota center (the lists goes on and on, really).

Want to know what else you can see from a low Earth orbit? Then I strongly suggest that you get a twitter account and follow @NASA_Astronauts Here, you will get live tweets from the individuals manning the ISS.

~Jolene

Sources:

The Great Wall from Space:
http://www.nasa.gov/vision/space/workinginspace/great_wall.html

The Wall from the Moon:
http://www.astronomy.com/News-Observing/Astronomy%20Myths/2009/11/You%20can%20see%20the%20Great%20Wall%20of%20China%20from%20the%20Moon.aspx

While astronauts from the ISS are looking down at Earth, we are looking up at it. Check out these two amazing pictures taken by people who’ve turned their eyes skyward to the international icon.

The Moon and the ISS
http://www.fromquarkstoquasars.com/?p=529

The ISS Transiting the Moon
http://www.fromquarkstoquasars.com/?p=543

Advertisements

One thought on “What Earth Objects are Visible from Space?

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s