Understanding the Earth's Fragile Atmosphere
The Earth spans 12,742 kilometres (7,918 miles) in diameter, yet the atmosphere surrounding it is remarkably thin in comparison to the planet's size.
British spelling.
Most experts regard an imaginary line 100 kilometres (62 miles) straight up from the surface of the Earth as the beginning of space; it is known as the Karman line. Approximately 90% of the atmosphere lies below this line.
The farther the atmosphere stretches upwards, the thinner, or less dense, it becomes.
The at…