The Herschel Space Observatory pictured the golden gaseous strands in the interstellar cloud IC5146, which is around 1,500 light years away from Earth.
It contains the dramatic blue Cocoon Nebula, seen on the left, which is connected to a network of filaments of dust and gas.

The cosmic filaments may be created by shockwaves from exploding stars. The region in the picture is around 15 light years across. Red shows colder gas and dust, while blue and green are warmer material which is being heated by stars which have already formed
Stars form along the densest parts of these filaments, but how the filaments form has been a mystery.
In optical light, the gas and dust look like opaque stripes and it is only in the infrared that they can be seen in detail.
The resolution of Herschel has allowed astronomers to measure the widths of the filaments. Surprisingly, they were all found to be almost the same width - 0.3 light years across or about 20,000 times the distance of Earth from the Sun.
Scientists had expected a wide range or widths so the fact they are the same gives a clue as to their formation.
By comparing them with computer simulations, the astronomers have concluded that the filaments may be formed when slow shockwaves dissipate in the interstellar clouds.
The shockwaves are the result of the energy produced by exploding stars, which cause a great deal of turbulence in the surrounding regions.


Network of interstellar filaments in Polaris as imaged by ESA's Herschel space observatory (seen before launch, right). These filaments are not yet forming stars
These waves travel through our Milky Way galaxy, sweeping up gas and dust and forming the dense filaments we see today.
Since the interstellar clouds are extremely cold, at around 10 degrees above absolute zero (or -263C), the speed of sound is relatively slow – at just 450 mph compared with 760 mph at sea level here on Earth.
This means that the slow shockwaves are the interstellar equivalent of sonic booms. As they lose energy in the clouds, they leave behind these filaments of compressed gas and dust.

This region is in the constellation of Cygnus, which is part of the Gould Belt, a ring of similar star forming regions around the sky.(dailymail.co.uk)

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