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[Music throughout] Hi, I'm Tom Essinger-Hileman.

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I'm an astrophysicist at NASA's
Goddard Space Flight Center

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in the Observational Cosmology
Laboratory.

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I use sensitive microwave telescopes
to try to understand

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the composition, origins
and history of our universe.

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This image is our first baby
picture of the universe, taken

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by the Cosmic Background Explorer,
or COBE satellite.

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Really, I think what's so interesting about this
is it gives you an idea

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of what you would see if you looked out
of the sky with microwave eyes.

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We look out at the sky
and we see a bunch of stars.

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Maybe we see our galaxy.

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But if you had the ability to look out
at microwave wavelengths,

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this is the sort of image that you would see,
you’d see a very uniform sky

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with these slight bright and dim patches.

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You'd be looking back

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to some of the earliest moments
in the history of our universe.

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COBE operated from 1989 to 1993,

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and COBE revolutionized
our understanding of the universe by

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observing the cosmic microwave background
that you're seeing here — the CMB.

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The CMB is remnant

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light from just 380,000 years
after the Big Bang,

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when the universe was transitioning
from a hot, dense plasma

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to a cooler neutral gas
of predominantly hydrogen and helium.

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At this early time, galaxies and stars hadn't formed.

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What we're seeing in this image of the CMB

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is the seeds of future galaxies,

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the red and blue patches in this map of the sky

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represent more and less dense regions

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in that early universe, and the more dense
regions clumped together

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to form the galaxies that we see
in the universe today.

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This was a first of its kind measurement

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of tiny fluctuations in the microwave brightness
of the sky.

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The DMR instrument
very precisely measured

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these tiny differences at wavelengths from
3 to 10 millimeters.

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that's around where your cellphone operates.

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The CMB is remarkably uniform;

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these fluctuations are just one part in 100,000

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of the overall 2.7 Kelvin temperature of the CMB.

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And they're on very large angular scales,
on very large physical scales in our universe.

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Future measurements

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were able to look at this map of the sky

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in greater detail, and with greater angular resolution.

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The universe when this was emitted

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was about a thousand times smaller,
and about a thousand times hotter.

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So when the cosmic microwave
background was emitted,

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this light peaked up in the visible.

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The universe as a whole has been expanding
and cooling, and the cosmic

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microwave background
has been cooling along with it.

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the light has shifted to longer wavelengths:
into the microwave

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and closer to the radio part of the spectrum.

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The idea that you can answer
fundamental questions about the history

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of our universe with a map like this
that we're seeing here is just amazing.