How high is space?

Jul 26, 2013 by Fraser Cain
The edge of space. Credit: NASA

Look up, there's space. Astronomically speaking, it's right there, just outside a thin layer of atmosphere. But how far away is it? How high is space?

Space is defined by the point at which the Earth's atmosphere ends, and the vacuum of takes over.

As you can probably imagine, with such a subjective definition, people disagree on exactly where space begins.

The first official definition of space came from the National Advisory Committee for Aeronautics (the predecessor to NASA), who decided on the point where atmospheric pressure was less than one pound per square foot.

This was the altitude that airplane control surfaces could no longer be used, and corresponded to roughly 50 miles, or 81 kilometers.

Any NASA test pilot or astronaut who crosses this altitude is awarded their astronaut wings.

Shortly after that definition, the aerospace engineer Theodore von Kármán calculated that above an altitude of 100 km, the atmosphere would be so thin that an aircraft would need to be traveling at to derive any lift.

This altitude was later adopted as the Karman Line by the World Air Sports Federation.

This video is not supported by your browser at this time.

When Felix Baumgartner broke the record for the highest freefall in 2012, he jumped from an altitude of 39 kilometers, less than halfway to space, according to NASA's definition.

But the atmosphere of Earth extends far out into space.

Even though it orbits at an altitude of more than 400 kilometers, the International Space Station needs to be constantly boosted because of friction with the atmosphere.

Satellites that orbit at a higher altitude can orbit for decades, or even hundreds of years without slowing down from atmospheric drag.

But the Earth's , also known as the , extends out to an altitude of 10,000 km above the planet. Although the atmosphere is tenuous, there are more gas particles in this region than interplanetary space.

Whatever the exact definition of space you use, if you can get above 100 kilometers, I think you deserve your astronaut wings.

Explore further: Computer model shows moon's core surrounded by liquid and it's caused by Earth's gravity

Related Stories

Clouds over the southern Indian Ocean

Mar 20, 2013

(Phys.org) —Marine stratocumulus clouds stretched across the southern Indian Ocean in early March 2013. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite acquired this natural-color ...

Supersonic skydiver's records confirmed

Feb 22, 2013

Austrian skydiver Felix Baumgartner broke three world records when he jumped from the edge of space in October, the World Air Sports Federation confirmed on Friday.

Recommended for you

Image: NASA's SDO observes a lunar transit

15 hours ago

On July 26, 2014, from 10:57 a.m. to 11:42 a.m. EDT, the moon crossed between NASA's Solar Dynamics Observatory and the sun, a phenomenon called a lunar transit.

Image: Tethys in sunlight

15 hours ago

Tethys, like many moons in the solar system, keeps one face pointed towards the planet around which it orbits. Tethys' anti-Saturn face is seen here, fully illuminated, basking in sunlight. On the right side ...

User comments : 0