No Human Has Ever Left Earth’s Atmosphere, Here's Why

Summary

Recent observations have revealed that Earth's atmosphere, specifically the exosphere, extends much further than previously thought, reaching up to 630,000 kilometers and encompassing the moon. The discovery was made using the Solar Wind Anisotropies Instrument (SWAN), which analyzed the geocorona's glow caused by the reflection of UV light from hydrogen atoms. This challenges our understanding of where space begins and has implications for future space observations, particularly regarding Lyman-alpha radiation measurements.

Takeaways

• 🌍 The Earth's atmosphere is much larger than previously thought, extending past the Moon.
• 🛰 The Kármán Line, at 100 kilometers above sea level, is commonly considered the boundary between Earth's atmosphere and space.
• 🚀 The Federation Aéronautique Internationale (FAI) defines the Kármán Line as the start of space for conventional aeronautic vehicles.
• 🌌 Some astrophysicists and organizations like NASA suggest the boundary should be at 80 kilometers due to orbital momentum effects on satellites.
• 🌁 The Earth's atmosphere consists of layers including the troposphere, stratosphere, mesosphere, thermosphere, and exosphere.
• 🌌 The exosphere, previously thought to end at 200,000 kilometers, may actually extend up to 630,000 kilometers based on geocorona observations.
• 🌕 The Moon is technically within the Earth's atmosphere, according to the new understanding of the exosphere's extent.
• 🛰️ The Solar Wind Anisotropies Instrument (SWAN) was instrumental in measuring and analyzing the geocorona's full extent.
• 🌞 The geocorona's glow is created by the reflection of the Sun's UV light off the hydrogen atoms in the exosphere.
• 🔬 Lyman-alpha radiation, observable by SWAN, is crucial for understanding the distribution of matter in space and宇宙 expansion.
• 🔭 Space telescopes within the exosphere will need to account for the geocorona's density and Lyman-alpha radiation when observing the cosmos.

Q & A

What is the Karman Line and its significance in defining the boundary between Earth's atmosphere and space?

The Karman Line is an altitude of approximately 100 kilometers above mean sea level and is recognized by the Fédération Aéronautique Internationale as the boundary where space begins. It is significant because, at this altitude, the atmosphere becomes too thin for conventional aircraft to fly without reaching orbital velocity, necessitating the use of astronautic vehicles.

Why is there a debate over the exact location where space begins?

There is no official international consensus on where space begins because some astrophysicists argue for a lower boundary at 80 kilometers above mean sea level based on orbital momentum, while NASA and the U.S. Air Force also use this altitude, differing from the FAI's definition.

What are the different layers of Earth's atmosphere mentioned in the script?

The script mentions the troposphere, where weather occurs and necessary gases for life are found; the stratosphere, where commercial airlines fly to avoid turbulence; the mesosphere, where meteors burn up; the thermosphere, which includes the Karman Line and where astronauts experience weightlessness; and the exosphere, the final layer before outer space.

What is the geocorona and how does it relate to the exosphere?

The geocorona is a glow created when the gases in the exosphere reflect the Sun's UV light. It is related to the exosphere as it represents the outermost extent of Earth's atmospheric hydrogen and helium atoms, which were recently discovered to extend up to 630,000 kilometers away from Earth.

How did astronomers determine that the exosphere extends further than previously thought?

Astronomers used the Solar Wind Anisotropies Instrument (SWAN) to measure and analyze the full extent of the geocorona, revealing that the exosphere extends much further than previously known, to the point of encompassing the moon.

What is the significance of the Lyman-alpha radiation in the context of the exosphere?

Lyman-alpha radiation is a specific wavelength that interacts with hydrogen atoms in the exosphere. It is significant because it can be measured by astrophysicists to observe cosmological structures and helps in understanding the distribution of matter in space and the expansion of the universe.

How does the discovery of the geocorona's extent affect space telescopes?

Space telescopes within the exosphere will need to consider the denser geocorona and the Lyman-alpha baseline level when making measurements, as these factors can affect observations of the night sky.

What is the practical impact of the discovery that the moon is technically within Earth's atmosphere?

While the discovery is remarkable, it does not change space travel in practical ways. The moon is still considered to be in space for the purposes of space exploration and travel.

How did the observations of the geocorona come to light?

The observations were made by SWAN in the late 1990s but were only recently rediscovered and analyzed from the archives, leading to the new insights about the extent of Earth's atmosphere.

What role does the exosphere play in shielding Earth from the sun's radiation and the cold of space?

The exosphere, as the outermost layer of Earth's atmosphere, contains hydrogen and helium atoms that gradually dissipate into space. While it is not as dense as the lower layers, it still contributes to the overall protective barrier against solar radiation and the cold vacuum of space.

What is the potential impact of this discovery on future space observations and research?

The discovery could lead to more accurate observations of deep space by accounting for the geocorona's influence on Lyman-alpha radiation. It may also inspire further research into the outer limits of Earth's atmosphere and its interactions with space.