Outer

The term "outer spaces" (or "outer space") can refer to several completely different concepts depending on the context you are looking for.

Outer Space (The Universe)

Most commonly, Outer Space refers to the near-vacuum expanse that exists beyond Earth's atmosphere and between celestial bodies. 

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• The Boundary: On Earth, it officially begins at the Kármán line (100 kilometers or 62 miles above sea level).

• Environment: It is a near-perfect vacuum made up of low-density particles (mostly hydrogen and helium plasma), electromagnetic radiation, magnetic fields, and cosmic dust.

• Temperature: The baseline temperature of deep space is an incredibly cold 2.7 Kelvin (-270°C or -455°F). 

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Outer space means the physical universe and empty expanse that exists beyond Earth's atmosphere and between celestial bodies like planets, stars, and galaxies. 

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According to the Merriam-Webster Dictionary, it is the region immediately outside our atmosphere, extending broadly into interplanetary and interstellar space. You can read more broad definitions on Encyclopædia Britannica or the Cambridge Dictionary. 

Key Features of Outer Space

• Near-Vacuum: It is mostly empty with extremely low particle densities, mostly hydrogen and helium plasma.

• Cold Temperature: The baseline temperature rests at 2.7 kelvins (−270 °C or −455 °F) due to leftover radiation from the Big Bang.

• Where It Begins: Many scientists use the Kármán line, located 100 kilometers (60 miles) above sea level, as the dividing mark where Earth's atmosphere ends and space begins. 

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What is Found There

• Celestial Bodies: Stars, planets, moons, asteroids, and comets.

• Large Structures: Whole galaxies and massive galaxy clusters.

• Cosmic Material: Cosmic rays, magnetic fields, and interstellar dust.
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