The European Space Agency recently released the first detailed all-sky images taken from its Planck satellite mission, the latest satellite to probe the “afterglow” of the Big Bang.

This is the radiation coming toward us from all directions from a time when the universe was only 380,000 years old, just after it had cooled sufficiently so that the protons in the hot gas could capture electrons to form neutral hydrogen and the universe then became transparent, and the ambient thermal background of radiation could travel unimpeded to us today.

In the intervening 13.7 billion years or so this radiation has cooled to close to 3 degrees above absolute zero and comes to us in the form of microwaves. In fact for those of us old enough to remember television before cable, when the TV stations went off the air and the screen filled with static, about 1 percent of the static visible on the screen was due to this radiation from the Big Bang.

In spite of this, this signal actually remained hidden until it was accidentally found in 1965 by Robert Wilson and Arno Penzias, who later shared the Nobel Prize for its discovery, which confirmed the Big Bang origin of our universe.

Because this radiation is so cold, it took almost 30 years before a satellite was launched into space by NASA — to get away from the warm background coming from the Earth and the absorption of radiation in our atmosphere — with a sensitivity great enough to actually image this signal. George Smoot, who along with John Mather was awarded a Nobel Prize for this work, exclaimed that looking at this image was like staring at the “face of God.”

This hyperbole can perhaps be forgiven, given the excitement of discovery, but any structure Smoot may have claimed to see was not unlike searches for images of animals in the clouds. The sensitivity of the experiment at the time was barely enough to separate the signal from other random backgrounds in the detector.

Another 20 years and now Planck has produced an exquisite picture whose fine-grained detail displays “hotspots” and “coldspots” in this background over the whole sky that represent variations in temperature of less than 1/10,000th of a degree from place to place. These miniscule fluctuations nevertheless reflect small excesses of matter that would later grow due to gravity to form all the structures we observe today — galaxies, stars, planets, and everything they house.