Scientists Observe Light Of "Cosmic Dawn" With Telescope On Earth For The First Time Ever

Astronomers have used Earth-based telescopes to observe "Cosmic Dawn", which is the early period in the universe's history, around 800 million years after the Big Bang, when the first stars and galaxies formed, emitting light that ended the cosmic dark ages.

This era was a significant milestone in the universe's evolution as massive stars and galaxies were formed and the universe's structure and composition were shaped.

Scientists have used James Webb Space Telescope (JWST) observations of distant galaxies to get insights into the cosmic dawn. Computational models also help understand galaxy formation and evolution.

"People thought this couldn't be done from the ground. Astronomy is a technology-limited field, and microwave signals from the Cosmic Dawn are famously difficult to measure," team leader and Johns Hopkins professor of physics and astronomy, Tobias Marriage, said in a statement.

"Ground-based observations face additional challenges compared to space. Overcoming those obstacles makes this measurement a significant achievement," Marriage added.

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Cosmic dawn insights shed light on the universe's early stages, providing an understanding of the universe's origins.

The scientists were able to get a new glimpse of Cosmic Dawn using the Cosmology Large Angular Scale Surveyor (CLASS), which is an array of telescopes located high in the Atacama Desert region of Northern Chile.

The main objective of CLASS is to observe the Cosmic Microwave Background (CMB), which is a cosmic fossil left over from an event just after the Big Bang.

The changes in the atmosphere, weather and temperature can distort the light, broadcast radio waves, radar, and satellites can access their signal on Earth.

The light from Cosmic Dawn is extremely faint as the wavelength is in millimetres, which is obvious as it has travelled to us for 13 billion years and more. The signal from polarised microwave light is about a million times fainter.

Polarisation means the orientation of oscillations or vibrations in a wave, such as light or electromagnetic waves. This can happen when light hits an object and scatters off it.

"When light hits the hood of your car and you see a glare, that's polarization. To see clearly, you can put on polarized glasses to take away glare," said team member Yunyang Li, who was a PhD student at Johns Hopkins.

"Using the new common signal, we can determine how much of what we're seeing is cosmic glare from light bouncing off the hood of the Cosmic Dawn, so to speak," added Yunyang, who was a fellow at the University of Chicago while this research was being conducte