The Planck spacecraft has delivered quite a payload of preliminary data on the origins of our Universe, and now the European Space Agency (ESA) is letting us catch a glimpse of Planck’s bounty. Named for German physicist and Nobel laureate Max Planck, the ESA launched Planck in May 2009 from the Guiana Space Centre. The spacecraft settled into a stable orbit along Earth’s nightside in a few months later. Earth’s nightside is an ideal spot for space-bound observatories: permanently shielded from the sun, spacecraft have an unobstructed view of the visible cosmos.
At the end of last summer, Planck began its ambitious mission: a survey of the entire sky. But Planck’s mission isn’t a simple pictorial survey (we’ve done that before). Planck was launched to survey the sky for wavelengths of the electromagnetic spectrum that we can’t see. Microwaves and very far infrared have longer wavelengths than visible light (see figure below), and Planck is capturing those wavelengths in its survey of the visible Universe.
It took the Planck spacecraft a little over six months to complete its first microwave and very far infrared survey of the sky, and made use of instruments designed and built by both the ESA and NASA. The embedded videos below illustrated how Planck completed this survey.
The fruits of Planck’s labor are shown below, in the spacecraft’s first microwave and very far infrared image of the sky:
The quality of Planck’s image and density of data gathered were so high that the ESA immediately set Planck on a follow-up mission to collect three more full sky images. This extended mission will keep Planck busy for well over the next year, as the spacecraft continues its scans of the sky and transmits vast amounts of data back to Earth. ESA scientists won’t be able to release the full spectrum of Planck’s findings until the end of 2012 at the earliest, but an early analysis of Planck’s first full sky image can help us understand what they’re looking for.
Most of the above image is dominated by parts of the Milky Way Galaxy, the same galaxy in which our solar system resides. The core of the Milky Way, where many young stars are born these days, runs in a bright purple horizontal strip across the center of the image. This strip is called the galactic plane. We can’t see any actual stars since this image was created using microwave and very far infrared wavelengths. But, the sheer intensity of microwaves reveals the flurry of starbirth in those portions of our galaxy. Visit the Chromoscope website to compare full sky views with visible light, microwaves, and other electromagnetic spectrum wavelengths. There, you can see how the Milky Way arm in our skies is a huge source of the microwave radiation that Planck has picked up.
The lighter blue and white swirls emanating from the galactic plane are also echoes of our galaxy’s intense starbirth activity. This continuum of gas and dust flows thousands of light years above and below the galactic plane. While beautiful, the Milky Way and its echoes are actually not the parts of this image that get ESA scientists so excited. Instead, scientists are focusing most on the mottled deep fuchsia, red, and orange patterns at the poles of the full sky image. Those patterns depict cosmic microwave background radiation (CMBR). CMBR is literally an echo of the Big Bang, the singular event which created the Universe some 13.7 billion years ago. The Universe has expanded rapidly sense then and changed quite a bit in structure. For example, when the Universe was first created, temperatures were too hot for even atomic matter (like atoms and elements) to exist. Thus, over its 13.7 billion year history, the Universe has changed quite a lot. However, since microwaves (like visible light) only travel at a finite speed, the cosmic microwave background radiation picked up this year by Planck is a snapshot not just through space, but through time.
The ESA and other space agencies are fascinated by CMBR because of what it can tell us about the formation of the early Universe. The patterns of CMBR picked up by Planck show us what the Universe was like before there were any stars, galaxies, or galactic clusters. The mottled color patterns in the CMBR indicate slight variations in temperature and density of the material, which Planck’s sensitive instruments can pick up. Those subtle differences in temperature and density in CMBR probably reveal sections of the Universe that developed into very different structures: dense areas became fierce galactic clusters, while largely empty sections became more mysterious voids that we are still trying to understand. In addition, ESA scientists are hoping that Planck’s scans of CMBR will help answer questions about how the young Universe first expanded and how matter was partitioned into different clusters in the Universe. Scientists have predicted that, very shortly after the Big Bang event, the Universe expanded at an incredibly rapid rate, faster than the speed of light. They call this brief expansion event the “Inflation,” and ESA scientists are hoping that signatures of the Inflation are imprinted in CMBR.
In order to pick up signatures of the Inflation, however, ESA scientists will need to collect more images of the full sky (which Planck is doing right at this moment). Scientists will also regrettably have to get rid of the Milky Way Galaxy. Not literally (which is good, since we live in the Milky Way). However, those spectacular images of the galactic plane and the dust and gas swirling above and below it from Planck’s first full sky observations obstruct a lot of CMBR. The Milky Way is literally in the way. Thus, the ESA is working to digitally remove the Milky Way and its signatures from Planck’s scans to unearth the CMBR signatures beneath. They hope the full sky CMBR patterns will help address fundamental questions about the Inflation and the mysterious structure of our Universe. However, this complex analysis will likely take several years to complete. In the meantime, Planck is taking plenty of pictures, so enjoy the view.
Planck’s first image of the full sky provided courtesy of the ESA.