Most astronomers believe the Universe began with a ‘Big Bang’ 13.7 billion years ago. Before this, the entire Universe was squashed inside a bubble thousands of times smaller than a pinhead. Then, it suddenly exploded, and the Universe we know was born. The faint glow of light collected by Planck is called cosmic microwave background radiation. It fills the whole Universe, surrounding Earth in every direction. Some call it an ‘echo of the Big Bang’, because it was the first light to exist in the Universe after its explosive beginning.
Wanaastronomia wengi wanaamini Ulimwengu ulianza na ‘Big Bang’ miaka bilioni 13.7 iliyopita. Kabla ya hili, Ulimwengu mzima ulibanwa ndani ya mapovu maelfu ya mara ndogo kuliko kichwa cha pini. Kisha, ililipuka ghafla, na Ulimwengu tunaojua ukazaliwa. Mwangaza hafifu wa mwanga uliokusanywa na Planck unaitwa mionzi ya mandharinyuma ya microwave. Inajaza Ulimwengu wote, unaozunguka Dunia katika kila upande. Wengine huiita ‘mwangwi wa Mlipuko Mkubwa’, kwa sababu ulikuwa ni mwanga wa kwanza kuwepo katika Ulimwengu baada ya kuanza kwa mlipuko.