This month, we'll take a closer look at the cosmic microwave background. Sometimes called 'the afterglow of creation', this extremely faint microwave glow is considered one of the most convincing pieces of evidence for the Big Bang theory. But how is it that we are still observing this ancient light?
As we've seen in earlier parts of this series, space is expanding. Since the amount of matter in the Universe remains fairly constant, the increasing volume means that the average density of cosmic matter is decreasing over time. That means the density of the Universe must have been much higher in the distant past.
Right after the Big Bang, before there were any galaxies, stars or planets, elementary particles were packed almost shoulder to shoulder, and the corresponding temperature was unimaginably high. This hot, dense plasma produced energetic radiation. However, individual light particles - photons - have trouble traversing such plasma-filled environments, as they are continuously absorbed (and re-emitted) by charged particles like electrons. In other words: the hot, early Universe was opaque.
Cosmic treasure trove
Leftover radiation from the explosion is key to unlocking the Universe around us
هذه القصة مأخوذة من طبعة May 2023 من BBC Sky at Night Magazine.
ابدأ النسخة التجريبية المجانية من Magzter GOLD لمدة 7 أيام للوصول إلى آلاف القصص المتميزة المنسقة وأكثر من 8500 مجلة وصحيفة.
بالفعل مشترك ? تسجيل الدخول
هذه القصة مأخوذة من طبعة May 2023 من BBC Sky at Night Magazine.
ابدأ النسخة التجريبية المجانية من Magzter GOLD لمدة 7 أيام للوصول إلى آلاف القصص المتميزة المنسقة وأكثر من 8500 مجلة وصحيفة.
بالفعل مشترك? تسجيل الدخول
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Voyager 1 is back online and exploring the unknown
An interstellar rescue brings the venerable spacecraft back after months out of action
When Haydn met the Herschels
Jonathan Powell on how the astronomer siblings inspired the famous composer
A quicker way to colourise your narrowband frames
Create a bicolour image in Siril using data from just two narrowband filters
Manhattanhenge
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A very British eclipse
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The spirit of the eclipse
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Cosmic rays
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Stones of the SOLSTICE
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Surfing spacetime with LISA
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