How high is space?

July 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.

The video will load shortly

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: Austria hails daredevil Baumgartner after space jump

Related Stories

Supersonic skydiver's records confirmed

February 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.

Clouds over the southern Indian Ocean

March 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 image ...

Recommended for you

First stars formed even later than previously thought

August 31, 2016

ESA's Planck satellite has revealed that the first stars in the Universe started forming later than previous observations of the Cosmic Microwave Background indicated. This new analysis also shows that these stars were the ...

Dawn sets course for higher orbit

August 31, 2016

After studying Ceres for more than eight months from its low-altitude science orbit, NASA's Dawn spacecraft will move higher up for different views of the dwarf planet.

Galaxy cluster discovered at record-breaking distance

August 31, 2016

A new record for the most distant galaxy cluster has been set using NASA's Chandra X-ray Observatory and other telescopes. This galaxy cluster may have been caught right after birth, a brief, but important stage of evolution ...

The rise and fall of galaxy formation

August 30, 2016

An international team of astronomers, including Carnegie's Eric Persson, has charted the rise and fall of galaxies over 90 percent of cosmic history. Their work, which includes some of the most sensitive astronomical measurements ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.