Meaning & use
von Kármán line
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Meanings
proper nounsingulartechnical
An imaginary boundary about 100 kilometers above sea level that is widely used to mark where Earth's atmosphere ends and space begins.
Grammar: Used with the: they crossed the von Kármán line.
Patterns
- cross the von Kármán line
- above the von Kármán line
The rocket crossed the von Kármán line two minutes after launch.
Passengers on the flight reached the von Kármán line and floated for a few minutes.
Space agencies often treat the von Kármán line as the border of space.
proper nounsingularphysics
The altitude at which air is so thin that an aircraft would need to travel faster than orbital speed to gain lift.
Grammar: Used in physics explanations of why wings stop working.
Above the von Kármán line, wings are of little use.
Engineers explain the von Kármán line in terms of air density and speed.
Common combinations
- cross the von Kármán line
- The capsule crossed the von Kármán line on its way up.
- reach the von Kármán line
- The balloon never reached the von Kármán line.
- above the von Kármán line
- Astronauts must travel above the von Kármán line.
- edge of space
- The von Kármán line marks the edge of space.
- 100 kilometers
- The von Kármán line sits at about 100 kilometers.
Synonyms and how they differ
- edge of space
- This is a casual phrase for the same idea, while von Kármán line names a specific altitude.
- Kármán limit
- This is another name for the line and refers to the same boundary.
- boundary of space
- This is more general and may refer to any proposed border, including the lower 80 km figure used by some agencies.
Word family
- atmosphere noun
- the layer of gases around Earth
- altitude noun
- height above sea level
- suborbital adjective
- reaching space without completing an orbit
- aerospace noun
- the industry of flight within and beyond the atmosphere
Commonly confused: von Kármán line or Kuiper belt? von Kármán line or Armstrong limit?
von Kármán line vs Kuiper belt
The Kuiper belt is a region of icy bodies far beyond Neptune, whereas the von Kármán line is near Earth, about 100 kilometers up.
von Kármán line vs Armstrong limit
The Armstrong limit is about 19 kilometers up, where liquids boil at body temperature, which is far lower than the von Kármán line.
Practice
The von Kármán line is best described as ___.
Choose one answer.
The von Kármán line is a convention at about 100 km that marks where space starts. Gravity never stops there, and it is far above where jets fly.
Make it your own
Write a sentence using “von Kármán line”, then check it and compare it with the examples above.