why is Space โDark?โฃ The Science Behind the โNight Sky
Jakarta – Despite the brilliance ofโค billions of stars, the nightโ sky appearsโ dark. This seeminglyโ simple observation sparked a centuries-old puzzle known as Olbers’ paradox: if the universe is infinite and filled with stars, why isn’t the entire sky ablaze with light?
Initial attempts โฃto resolve the โขparadox, such as those proposed by German astronomer Heinrichโฃ Olbers,โข suggested intervening dust clouds absorbed starlight. However,this ideaโค conflicted with the first law of thermodynamics,which dictates that absorbing material โwould re-emit energy as heat and light.
The 20th century brought a solution โwith the discovery of the universe’s expansion. This expansion causes the light from distant galaxies to shift towards the infrared, โultraviolet, and radio wave spectrums โ- wavelengths invisible to the human eye. Essentially, the universe would appear brighter if โขwe could detect these microwaves.
However, the complete explanation, as reportedโ by detikinet citingโ Today Orbitals, โคlies in the presence of anโฃ atmosphere.Inโ the near-vacuum of space, light lacks a medium forโฃ reflection.
On Earth, sunlight interacts with the โขatmosphere, causing light to scatter across the visible spectrum. Thisโ interaction between photons and atmospheric atoms, molecules, and dust creates the phenomenon of a bright sky. Earth’s atmosphereโ preferentiallyโฃ scatters blue light due to its shorter wavelength, resulting in a blue daytime sky. A similar, though less intense, effect occurs on Mars.
Conversely, planets or satellites lacking substantial atmospheres – like the Moon or Mercury – exhibit black skies even in direct sunlight, as documented by photographsโ from the Apolloโฃ missions.
(asj/fyk)