Why do we see so few stars in the sky?
What should we do about it?
Need to ionize these atoms? Or, more precisely, reionization, since they have already been ionized once before: even before they became neutral.
True, this process will take a lot of time and the participation of the billions of stars that form will emit ultraviolet ionizing radiation and fall on over 99% of the neutral atoms of the Universe. This is a gradual process, but it will take 550 million years to complete.
Until recently, we thought that reionization — this last phase of the Universe, which would make it transparent to visible light — occurred 450 million years after the Big Bang, but an additional factor in the form of 100 million years was determined by Planck’s latest observations.
This, in turn, does not mean that the oldest stars of the Universe were formed 100 million years later than we previously thought. This means that the first stars were formed much, much earlier than we can observe, and we did not have enough stars - and they did not live long enough - to reionize the Universe and make it transparent to light.In the universe, it was simply not enough to say “let there be light!” To see the first stars: this light must be able to pass freely through space.
There is no way to see them in the visible spectrum, no matter how good the Hubble Space Telescope, no matter how long it looks at these parts of the sky, it will never see the first stars, because the Universe is still opaque to visible light. .
But there is hope, and the James Webb space telescope has the potential to translate this hope into reality.
If you observe the long-wavelength light, these dusty structures of atoms and molecules may well be transparent for these wavelengths. Although Hubble may never see these stars, James Webb will peer into infrared (and rather long) waves and will be able to track their path to those eras when the Universe was transparent to visible light.
In other words, in just a few years we will be able to truly explore the first stars of the universe. Perhaps they are invisible to us, but it is the fault of our eyes, not the light.