Cosmic baby photo

The all-sky microwave image of the universe made by the Planck space telescope.

The all-sky microwave image of the universe made by the Planck space telescope.

  • Map of the entire sky at microwave wavelengths
  • Shows the afterglow of the Big Bang
  • Will lead to better understanding of cosmic evolution

Scientists operating Europe’s space telescope, Planck, have released the mission’s first image of the whole sky.

“This is the moment that Planck was conceived for,” says European Space Agency (ESA) Director of Science and Robotic Exploration, David Southwood.

Planck picks up microwave wavelengths. What it sees are microwaves coming from near and far in the universe.

In particular, it is studying the microwave “glow” left over from the Big Bang 13.7 billion years ago—the cosmic microwave background radiation (CMBR). When we look at the CMBR, we’re seeing the oldest view we’ve ever had of the universe.

The CMBR has cooled right down from its fireball days, and is now at a temperature of about –270 degrees Celsius (only 2.7 degrees above absolute zero).

The new image is a map of the microwaves picked up from all different directions in space.

The oval shape of the map is similar to an oval-projection map of Earth, where cartographers take a round object (the Earth) and spread it out onto a flat shape. With Planck, it is a microwave map of the sky that is spread onto a flat surface.

Artist's impression of Planck

An artist's impression of the Planck telescope in its near-Earth location in space.

Why is the universe clumpy?

Stretching across the middle of the map is a mess of microwaves that come from sources within our Milky Way galaxy.

Of more interest is the mottled, reddish areas above and below. This is where Planck can see past the Milky Way to the distant universe beyond. The mottling comes from tiny temperature differences from one point to another in the CMBR.

In 1992, a forerunner of Planck, the Cosmic Microwave Background Explorer (COBE) spacecraft made the first detailed map of the CMBR. It showed the mottling effect.

The mottling effect is thought to reflect the way the universe has become “clumpy”—a combination of huge voids of empty space, and vast clusters and superclusters of galaxies.

Astronomers want to know why matter in the universe tended to clump into the clusters and superclusters, leaving the huge voids behind. It’s thought that the Big Bang explosion was “non-uniform”, ie. stuff spread out unevenly.

The mottling effect in the CMBR is thought to reflect that unevenness.

The initial discovery of the CMBR with ground-based antennae in 1964 led to its discoverers winning the Nobel Prize for Physics. This was followed by up another Nobel Prize for Physics in 2006 for two of the leaders of the COBE mission.

A scientific Eldorado

Planck is only a quarter of the way through its four-year mission. In that time, it will make four complete scans of the cosmos, building a very detailed map of the CMBR.

“We’re not giving the answer. We are opening the door to an Eldorado where scientists can seek the nuggets that will lead to deeper understanding of how our Universe came to be and how it works now,” says Southwood.

“The image itself and its remarkable quality is a tribute to the engineers who built and have operated Planck. Now the scientific harvest must begin.”

Story by Jonathan Nally, Editor, SpaceInfo.com.au

Images courtesy ESA / LFI & HFI Consortia / C. Carreau

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