Understanding Cosmic Dawn

In this 15-minute "mini podcast", NASA astrosphysicist Michelle Thaller talks about the early universe, the cosmic dark ages, cosmic dawn and why these different stages happened.

Credit: NASA's Goddard Space Flight Center

Complete transcript available.

This artist's concept shows how the universe might have looked when it was less than a billion years old, about 7 percent of its current age. Star formation voraciously consumed primordial hydrogen, churning out myriad stars at an unprecedented rate. NASA’s Nancy Grace Roman Space Telescope will peer back to the universe’s early stages to understand how it transitioned from being opaque to the brilliant starscape we see today.

Credit: NASA, ESA, and A. Schaller (for STScI)

Alt text: This illustration depicts a mesmerizing and chaotic cosmic scene, filled with misshapen clumps and twists of white and purplish material on a black background. Most of the clumps are small, but a particularly large conglomeration extends from the lower-right of the frame up to the middle and nearly all the way across to the left side, sort of like billowing clouds. It's full of bulbous shapes outlined with glowing lavender tendrils. Bright groups of stars are concentrated in the center of each lobe, and also scattered more sparsely throughout the surrounding area.

This view from the James Webb Space Telescope contains more than 20,000 galaxies. Researchers analyzed 117 galaxies that all existed approximately 900 million years after the big bang. They focused on 59 galaxies that lie in front of quasar J0100+2802, an active supermassive black hole that acts like a beacon, located at the center of the image above appearing tiny and pink with six prominent diffraction spikes. The team studied both the galaxies themselves and the illuminated gas surrounding them, which was lit up by the quasar’s bright light. The observation sheds light on how early galaxies cleared the “fog” around them, eventually leading to today’s clear and expansive views.

Credits: NASA, ESA, CSA, Simon Lilly (ETH Zürich), Daichi Kashino (Nagoya University), Jorryt Matthee (ETH Zürich), Christina Eilers (MIT), Rob Simcoe (MIT), Rongmon Bordoloi (NCSU), Ruari Mackenzie (ETH Zürich); Image Processing: Alyssa Pagan (STScI) Ruari Macken

Alt text: A black background with stars shining throughout that range in size and color from white to gold and almost orange.

This audio is a human-read copy of the story text.

Complete transcript available.