Bounty Ended with 50 reputation awarded by PM 2Ring occurred May 25 at 7:04 7 added 156 characters in body edited May 21 at 11:04 pela 9,0012323 silver badges3939 bronze badges The figure below shows, in green, the brightness of the CMB as a function of time after the Big Bang. A secondary $$x$$ axis on top show the corresponding temperature of the Universe. The background color shows the color of the Universe as would be perceived by a human being, calculated by convolving the spectrum of the radiation with the response function of the human eye: The first few tens of thousands of years, the Universe is a pale sapphire blue, turning white as it reaches the temperature of the Sun ($$T_\odot \simeq 5\,778\,\mathrm{K}$$$$T_\odot \simeq 5\,780\,\mathrm{K}$$). At $$t\sim200\,\mathrm{Myr}$$, stars begin to form and the calculation of the spectrum becomes more complicated (so I've grayed it it out), but today the Universe has reached a cosmic latte (Bladry et al. 2001). Note that, as mentioned above, only between $$t\sim1\,\mathrm{Myr}$$ and $$t\sim6\,\mathrm{Myr}$$ — where the temperatures was $$1600\mathrm{K} \gtrsim T \gtrsim 500\mathrm{K}$$ — could you actually see anything; prior to this epoch you'd go blind, and after this epoch, it'd be too dim (but you could in principle still see the color using sunglasses/binoculars, respectively). The figure below shows, in green, the brightness of the CMB as a function of time after the Big Bang. A secondary $$x$$ axis on top show the corresponding temperature of the Universe. The background color shows the color of the Universe as would be perceived by a human being, calculated by convolving the spectrum of the radiation with the response function of the human eye: The first few tens of thousands of years, the Universe is a pale sapphire blue, turning white as it reaches the temperature of the Sun ($$T_\odot \simeq 5\,778\,\mathrm{K}$$). At $$t\sim200\,\mathrm{Myr}$$, stars begin to form and the calculation of the spectrum becomes more complicated (so I've grayed it it out), but today the Universe has reached a cosmic latte. Note that, as mentioned above, only between $$t\sim1\,\mathrm{Myr}$$ and $$t\sim6\,\mathrm{Myr}$$ could you actually see anything; prior to this epoch you'd go blind, and after this epoch, it'd be too dim (but you could still see the color using sunglasses/binoculars, respectively). The figure below shows, in green, the brightness of the CMB as a function of time after the Big Bang. A secondary $$x$$ axis on top show the corresponding temperature of the Universe. The background color shows the color of the Universe as would be perceived by a human being, calculated by convolving the spectrum of the radiation with the response function of the human eye: The first few tens of thousands of years, the Universe is a pale sapphire blue, turning white as it reaches the temperature of the Sun ($$T_\odot \simeq 5\,780\,\mathrm{K}$$). At $$t\sim200\,\mathrm{Myr}$$, stars begin to form and the calculation of the spectrum becomes more complicated (so I've grayed it it out), but today the Universe has reached a cosmic latte (Bladry et al. 2001). Note that, as mentioned above, only between $$t\sim1\,\mathrm{Myr}$$ and $$t\sim6\,\mathrm{Myr}$$ — where the temperatures was $$1600\mathrm{K} \gtrsim T \gtrsim 500\mathrm{K}$$ — could you actually see anything; prior to this epoch you'd go blind, and after this epoch, it'd be too dim (but you could in principle still see the color using sunglasses/binoculars, respectively). 6 added 27 characters in body edited May 21 at 8:20 pela 9,0012323 silver badges3939 bronze badges $$^\dagger$$I wrote a Python code called timeline to calculate $$\ell$$ and other quantities of the Universe as a function of time, available on GitHub here. $$^\dagger$$I wrote a Python code called timeline to calculate $$\ell$$ and other quantities of the Universe as a , available on GitHub here. $$^\dagger$$I wrote a Python code called timeline to calculate $$\ell$$ and other quantities of the Universe as a function of time, available on GitHub here. 5 Fixed typo edited May 21 at 8:06 PM 2Ring 4,24422 gold badges1414 silver badges2929 bronze badges The figure below shows, in green, the brightness of the CMB as a function of time after the Big Bang. A secondary $$y$$$$x$$ axis on top show the corresponding temperature of the Universe. The background color shows the color of the Universe as would be perceived by a human being, calculated by convolving the spectrum of the radiation with the response function of the human eye: The first few tens of thousands of years, the Universe is a pale sapphire blue, turning white as it reaches the temperature of the Sun ($$T_\odot \simeq 5\,778\,\mathrm{K}$$). At $$t\sim200\,\mathrm{Myr}$$, stars begin to form and the calculation of the spectrum becomes more complicated (so I've grayed it it out), but today the Universe has reached a cosmic latte. Note that, as mentioned above, only between $$t\sim1\,\mathrm{Myr}$$ and $$t\sim6\,\mathrm{Myr}$$ could you actually see anything; prior to this epoch you'd go blind, and after this epoch, it'd be too dim (but you could still see the color using sunglasses/binoculars, respectively). The figure below shows, in green, the brightness of the CMB as a function of time after the Big Bang. A secondary $$y$$ axis on top show the corresponding temperature of the Universe. The background color shows the color of the Universe as would be perceived by a human being, calculated by convolving the spectrum of the radiation with the response function of the human eye: The first few tens of thousands of years, the Universe is a pale sapphire blue, turning white as it reaches the temperature of the Sun ($$T_\odot \simeq 5\,778\,\mathrm{K}$$). At $$t\sim200\,\mathrm{Myr}$$, stars begin to form and the calculation of the spectrum becomes more complicated (so I've grayed it it out), but today the Universe has reached a cosmic latte. Note that, as mentioned above, only between $$t\sim1\,\mathrm{Myr}$$ and $$t\sim6\,\mathrm{Myr}$$ could you actually see anything; prior to this epoch you'd go blind, and after this epoch, it'd be too dim (but you could still see the color using sunglasses/binoculars, respectively). The figure below shows, in green, the brightness of the CMB as a function of time after the Big Bang. A secondary $$x$$ axis on top show the corresponding temperature of the Universe. The background color shows the color of the Universe as would be perceived by a human being, calculated by convolving the spectrum of the radiation with the response function of the human eye: The first few tens of thousands of years, the Universe is a pale sapphire blue, turning white as it reaches the temperature of the Sun ($$T_\odot \simeq 5\,778\,\mathrm{K}$$). At $$t\sim200\,\mathrm{Myr}$$, stars begin to form and the calculation of the spectrum becomes more complicated (so I've grayed it it out), but today the Universe has reached a cosmic latte. Note that, as mentioned above, only between $$t\sim1\,\mathrm{Myr}$$ and $$t\sim6\,\mathrm{Myr}$$ could you actually see anything; prior to this epoch you'd go blind, and after this epoch, it'd be too dim (but you could still see the color using sunglasses/binoculars, respectively). 4 edited body edited May 21 at 7:38 pela 9,0012323 silver badges3939 bronze badges 3 Plotted B(t) edited May 21 at 7:32 pela 9,0012323 silver badges3939 bronze badges 2 Discussed brightness today edited May 16 at 10:58 pela 9,0012323 silver badges3939 bronze badges 1 answered May 16 at 10:32 pela 9,0012323 silver badges3939 bronze badges