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By Williams JamesPublished 2 months ago 3 min read


In the annals of space exploration history, there has always been a lingering debate regarding the demarcation between Earth's atmosphere and the vast expanse of outer space. Recently, scientific observations have presented us with a fascinating revelation: Earth's atmosphere is far more extensive than we previously imagined, extending beyond the moon itself.

Traditionally, space has been defined by the famous Karman Line, positioned approximately 100 kilometers above mean sea level. According to the Federation Aeronautique Internationale (FAI), the organization tasked with determining these defining rules, crossing the Karman Line signifies entry into space. The rationale behind this boundary lies in the fact that once you surpass this altitude, the Earth's atmosphere becomes too thin to support conventional aeronautic vehicles, such as airplanes, without achieving orbital velocity. Therefore, specialized astronautic vehicles become necessary.

Nevertheless, it's important to note that while the Karman Line's designation is widely recognized, there is no official international consensus regarding the precise threshold at which space commences. Some astrophysicists argue that it should be set at 80 kilometers above mean sea level, owing to the way orbital momentum influences satellite objects. NASA and the U.S. Air Force also adopt an 80-kilometer threshold to define space, designating those who traverse this line as astronauts.

To gain a comprehensive understanding of Earth's atmosphere, we must delve into its layered composition. Our atmosphere is not a uniform entity but rather comprises distinct strata, each with its own unique characteristics and functions. These layers include:

Troposphere: The troposphere is the layer closest to Earth's surface, where all our familiar weather phenomena occur. It contains the necessary gases for human survival and breathing, making it vital for sustaining life.

Stratosphere: Positioned just above the troposphere, the stratosphere is a region commonly favored by commercial airlines due to its lower turbulence levels.

Mesosphere: The mesosphere is the layer where most meteors burn up upon entry into Earth's atmosphere. It is also the highest layer at which clouds can form.

Thermosphere: Beyond the mesosphere lies the thermosphere, the home of the elusive Karman Line. In this layer, astronauts start experiencing weightlessness, and it is where the International Space Station (ISS) orbits.

Exosphere: The exosphere is the outermost layer, characterized by a sparse composition of hydrogen and helium atoms. This region gradually fades into the vacuum of space and extends up to 200,000 kilometers away from Earth's surface, or so we thought.

Recent astronomical discoveries have expanded our understanding of the Earth's exosphere. The revelation comes from a remarkable instrument known as the Solar Wind Anisotropies Instrument (SWAN). SWAN's mission was to measure and analyze the geocorona, a luminous phenomenon created when the exosphere's gases reflect the Sun's ultraviolet (UV) light. This discovery, however, suggests that the exosphere might extend astonishingly farther than previously assumed, encompassing the moon's orbit. Essentially, this implies that the moon resides within Earth's atmosphere.

The groundbreaking insight into the exosphere's remarkable reach stems from SWAN's unique ability to observe Lyman-alpha radiation. This particular wavelength interacts with the hydrogen atoms in the exosphere. While Lyman-alpha radiation is typically invisible from Earth due to its absorption by the inner atmosphere, SWAN, positioned in space, has successfully captured and analyzed this data.

The implications of this discovery, while not immediately altering practical aspects of space travel, hold significant scientific value. The observation that sunlight interacts with exosphere hydrogen atoms, causing the formation of denser geocorona pockets and associated Lyman alpha radiation depending on the sun's position, has substantial consequences for space observations.

For example, space telescopes that operate within the exosphere will need to consider this newfound Lyman-alpha baseline when conducting observations of celestial phenomena. This adjustment could potentially enhance the accuracy and depth of our exploration and understanding of the cosmos.

Remarkably, these revelations have emerged from observations made by SWAN in the late 1990s, recently unearthed from research archives for further analysis. This discovery underscores the treasure trove of scientific knowledge that may be lurking in the archives, waiting to reshape our understanding of the universe.

In conclusion, while the boundary between Earth's atmosphere and outer space has long been a subject of debate and definition, the recent findings regarding the exosphere's remarkable reach have illuminated our understanding of our own planet's atmospheric limits. This revelation, driven by advanced technology and rigorous scientific inquiry, serves as a testament to the ever-evolving nature of our comprehension of the universe. As we continue to explore and study our cosmos, the boundaries of human knowledge continue to expand, pushing the frontiers of what is possible in our quest to understand the universe we inhabit.


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