DYK #21: View from space

How many times have you read a post stating "Great Wall of China is the only man-made object visible from  the moon with the naked eye". Received this as a part of 'amazing facts' e-mail from you friends?

Continue reading after the jump to find out the truth!

DYK #19: Tears in space

There is a myth floated by several facts-sites that astronauts cannot cry in space. This is not true (at least completely). There is some odd behavior due to no/low gravity in space.

Tears run down your face because of gravity, but they don't need gravity to form. When the tears get big enough they simply break free of the eye and float around.

Frank Culbertson, the ISS commander who was in space during the 9/11 attacks, wrote, on learning that a friend of him was captain of flight 77 which was crashed into the Pentagon:

"What a terrible loss," Culbertson writes, "but I'm sure Chic was fighting bravely to the end. And tears don't flow the same in space..."

Source: CNN

This also applies for sweat. There are several movies which depict odd behavior of liquids in space.

References:

1. http://www.badastronomy.com/mad/1998/cry_astronaut.html
2. http://edition.cnn.com/2001/TECH/space/10/15/attacks.culbertson/
3. http://history.nasa.gov/ap15fj/08day3_leak_hilltop.htm