This image shows a portion of the sky as seen by COBE, a satellite launched 25 years ago. It measured the "afterglow" of the Big Bang, which fills the universe with microwaves. Tiny variations in the temperature of this glow, shown in red and blue, show regions of different density. The denser concentrations of matter gave birth to the first stars and galaxies. COBE's top scientists later won the Nobel Prize for the craft's observations. [NASA/GSFC]
You are here
In the days before remote controls and cable TV, changing the channel often took you through unused channels filled with static. Most of that static came from the afterglow of the Big Bang — a background energy that fills the universe. It was first studied in detail by a spacecraft that was launched 25 years ago today.
Big Bang theory says the early universe was incredibly hot and dense. As it expanded, it cooled. We can still see the energy produced by that early period, though, as a microwave glow that comes from every direction in the sky.
Scientists discovered that glow in 1964. Early observations found absolutely no variations in it — it looked exactly the same in every direction. But that was a problem. It was hard to explain how such a smooth early universe could give rise to the “lumpy” modern universe, which is filled with galaxies and clusters of galaxies.
COBE — the Cosmic Background Explorer — was designed to look for tiny variations in the microwave background. And it found them. They amounted to only about one part in 20,000. Yet they represented the first structure in the universe — filaments of hot gas that clumped around strands of “dark matter.” Much of the gas eventually coalesced to form stars and galaxies — the universe we see today.
COBE’s creators received the Nobel Prize for their work — studying the afterglow of the Big Bang. More about the Big Bang tomorrow.
Script by Damond Benningfield, Copyright 2014
- ‹ Previous
- Next ›
Get Premium Audio
Listen to today's episode of StarDate on the web the same day it airs in high-quality streaming audio without any extra ads or announcements. Choose a $8 one-month pass, or listen every day for a year for just $30.