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The magnetic field emitted by our Galaxy has been revealed for the first time in a stunning new image.

Taken by  ESA's Planck satellite, it compiled from the first all-sky observations of 'polarised' light emitted by interstellar dust in the Milky Way.

The astronomical equivalent of looking through polarised sunglasses, it shows swirls, loops and arches that trace the structure of the magnetic field in our home galaxy, the Milky Way.

The Galaxy's magnetic field is revealed in a new image from ESA;s Planck satellite. This image was compiled from the first all-sky observations of polarised light emitted by interstellar dust in the Milky Way, and was obtained using detectors on Planck that act like polarised sunglasses.

Light is a very familiar form of energy and yet some of its properties are all but hidden to everyday human experience.

One of these – polarisation – carries a wealth of information about what happened along a light ray's path, and can be exploited by astronomers.

Light can be described as a series of waves of electric and magnetic fields that vibrate in directions that are at right angles to each other and to their direction of travel, according to ESA.

This can happen, for example, when light bounces off a reflective surface like a mirror or the sea. Special filters can be used to absorb this polarised light, which is how polarised sunglasses eliminate glare.

In space, the light emitted by stars, gas and dust can also be polarised in various ways.

'By measuring the amount of polarisation in this light, astronomers can study the physical processes that caused the polarisation,' the European Space Agency says.

'In particular, polarisation may reveal the existence and properties of magnetic fields in the medium light has travelled through.'

The new map was obtained using detectors on Planck that acted as the astronomical equivalent of polarised sunglasses.

In addition to its hundreds of billions of stars, our Galaxy is filled with a mixture of gas and dust, the raw material from which stars are born.

the European Space Agency's Planck satellite previously captured this microwave radiation image from the whole sky. In this image, the dust of the Milky Way is shown in blue, with a red band across the centre showing hot regions, while the mottled yellow area above and below represents relic radiation, otherwise known as the Cosmic Microwave Background, created in the fireball of the Big Bang 13.7 billion years ago, which is the oldest light in the Universe.

Even though the tiny dust grains are very cold, they do emit light but at very long wavelengths – from the infrared to the microwave domain.

If the grains are not symmetrical, more of that light comes out vibrating parallel to the longest axis of the grain, making the light polarised.

If the orientations of a whole cloud of dust grains were random, no net polarisation would be seen. However, cosmic dust grains are almost always spinning rapidly, tens of millions of times per second, due to collisions with photons and rapidly moving atoms.

Then, because interstellar clouds in the Milky Way are threaded by magnetic fields, the spinning dust grains become aligned preferentially with their long axis perpendicular to the direction of the magnetic field.

As a result, there is a net polarisation in the emitted light, which can then be measured.