StarDate: April 8, 2009

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[AUDIO: TV hiss]

If you remember the days before cable, satellite, and digital television, then you probably remember the snow -- the shimmering and hiss on "empty" channels. Some of that hiss was generated 13.7 billion years ago -- it's the "afterglow" of the Big Bang.

A new astronomy satellite will study this afterglow in the greatest detail to date. Its observations will tell us more about the Big Bang, the earliest structure in the universe, and the birth of the first stars and galaxies.

The satellite is called Planck. It's scheduled for launch this month aboard an Ariane rocket. It'll share the ride with another space observatory, called Herschel; more about its mission tomorrow.

The afterglow is known as the cosmic microwave background. It comes from almost 400,000 years after the Big Bang, when the universe became cool and thin enough for energy to pass through it. Over the eons it's cooled to just a few degrees above absolute zero.

This radiation forms a background glow that fills the entire sky. It's not quite smooth, though. Instead, there are tiny differences in temperature. Regions that are a little hotter were also denser -- "lumps" of matter that collapsed to form the first stars and galaxies.

Two earlier satellites mapped the background radiation. But Planck will provide a much sharper view, giving us a more detailed look at the very early universe. [AUDIO: more hiss]

Script by Damond Benningfield, Copyright 2009

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