The Milky Way's fingerprint reveals secrets

Do you think this picture is a frothy swirl in a coffee cup? Well, we don’t think the European Space Agency (ESA) was playing a prank on us when they said that this picture actually depicts the Milky Way’s magnetic lines and could help astronomers understand the history of the universe!

The image was from the Planck telescope which maps the sky using two state-of-the-art instruments. Although the mission was launched in 2009 and ended last year, scientists are still analysing the data Planck collected in its mission period. They hope it will enable them to understand how stars are formed completely.

Planck collects data by functioning like an astronomical pair of polarised sunglasses. Electromagnetic waves that make up light vibrate at right angles to each other and where they are travelling. If these vibrations are disturbed the light becomes “polarised”. You can see this happen even when light rays bounce off a reflective material like a mirror or the sea.

This image was created by compiling information from the first all-sky observation of polarised light emitted by interstellar dust in the Milky Way. The technique used is called integral convolution.

The finger-print-like swirls in the image trace the structure of the magnetic field in our galaxy. The dark line running horizontally through the centre corresponds to the Milky Way’s galactic plane – the area where majority of the galaxy’s mass lies.

The tangles in the image reveal the variations of polarisation patches which indicate strong polarised emissions. The furrows show the direction of the magnetic field projected on the plane of the sky.

Scientists hope the data will enable to them to understand the early history of the cosmos, from when the Universe was less than one second old to the period when stars were born, which is believed to be several hundred million years later.