ISS Astronauts See Earth’s Atmosphere as 1-Degree Blue Line, Witness 16 Daily Sunrises
Updated
Updated · spacedaily.com · Jul 18
ISS Astronauts See Earth’s Atmosphere as 1-Degree Blue Line, Witness 16 Daily Sunrises
1 articles · Updated · spacedaily.com · Jul 18
Summary
Aboard the ISS, crews orbit Earth every 90 minutes, producing about 16 sunrises and 16 sunsets a day and turning dawn and dusk into events that last only seconds.
From roughly 400 kilometres up, astronauts repeatedly describe the atmosphere as a thin blue band at the horizon; NASA astronaut Ed Lu said it appeared about one degree wide—roughly an index finger at arm’s length.
That effect comes from looking edge-on through atmospheric layers: blue light scatters strongly in daylight, while longer sunrise and sunset paths leave orange and red bands that can shift with dust, aerosols and clouds.
NASA says the atmosphere has no hard outer edge, but the view from orbit makes its small scale stark—the troposphere holds most air, water vapour and weather, and the atmosphere’s total mass is about one-millionth of Earth’s.
Accounts from Alexander Gerst, Scott Kelly, Christina Koch and others tie that visual shock to the “overview effect,” framing the thin limb as the narrow habitat containing nearly all human life.
Astronauts see a fragile, borderless world, but strategists call this irrelevant. Is the famous 'overview effect' a beautiful, but misleading, illusion?
As the ISS nears retirement, can its commercial successors replicate the profound 'overview effect' that has inspired astronauts for decades?