Different Science
Over the next few hundred million years, as stars began to shine, their light ionised the hydrogen and helium, enabling photons to flow freely and making the universe transparent, though the exact timing of this is uncertain.
Contact me with news and offers from other Future brandsReceive email from us on behalf of our trusted partners or sponsorsBy submitting your information you agree to the Terms & Conditions and Privacy Policy and are aged 16 or over.
That haze, the researchers say, causes the planet's upper atmosphere to be hotter than the layers below, creating an environment where carbon dioxide emits light rather than absorbing it, which could explain the lack of an expected dip in previous observations.
The universe has expanded greatly since it was born about 13.8 billion years ago in the Big Bang, and that means the light from early galaxies appears reddened by the time it reaches Earth, much as how an ambulance siren sounds lower-pitched to people as the vehicle drives away.
Ray Jayawardhana at Johns Hopkins University in Maryland and his colleagues found these strange worlds in the NGC 1333 star cluster using the James Webb Space Telescope.