The European Space Agency’s Planck telescope has new information about the universe’s first stars. Scientists have thought star formation began 440 million years after the Big Bang. The Planck telescope revises that number to 550 million years after the birth of the universe.
“While these 100 million years may seem negligible compared to the Universe’s age of almost 14 billion years, they make a significant difference when it comes to the formation of the first stars,” said Marco Bersanelli of Universita degli Studi di Milano, Italy.
The period when stars first began to shine is known as the ‘epoch of reionization.’ Before this, the universe was in a ‘dark age’ for 550 million years.
Light from the first starts helped pull the universe out of this ‘dark age’ It helped clear the fog of hydrogen atoms that had filled the entire cosmos. This also led hydrogen atoms to turn back into electrons and protons.
With the ‘fog’ lifted, electrons and protons could combine and form neutral atoms. Before, they would have been ripped apart by incoming photons.
“The process of reionisation was complete by the time that the Universe was about 900 million years old,” according to George Efstathiou of the University of Cambridge. This 900 million years old figure comes from detailed observations by NASA’s Hubble Space Telescope.
According to the ESA, the new end date for the ‘dark ages’ could make it easier to detect the first galaxies. A new generation of telescopes should be able to detect these early galaxies, starting with the James Webb Space Telescope.
Planck scientists are still pouring over the vast collection of data. “The harvest of discoveries has just begun,” says Jan Tauber.
Image credits: ESA, top image is a visualization of the oldest light in the universe.