![Big Flash Image source: NASA/WMAP Science Team Big Flash Image source: NASA/WMAP Science Team](http://www.timeone.ca/wp-content/uploads/2013/03/Big-Flash-e1403879213152.jpg)
Classification: measurement
Chapter: Preface
The Big Flash is the low-frequency (Cosmic Microwave Background) radiation emitted by all parts of the universe when space became transparent as the temperature fell below 3000 °C about 370,000 years after the Beginning. Since 1990 it has been imaged by three special satellites and by other methods.