Stars and planets form in clouds of dust and gas called nebulae. One of the nearest is the Orion Nebula. This new image has been taken at infrared wavelengths and sees more deeply into the nebula than ever before.

Peering through the veils of dust and gas, it reveals not just stars but many more planetary mass objects than expected.



Lead scientist Holger Drass, Astronomisches Institut, Ruhr-Universität Bochum, Germany, says, “Our result feels to me like a glimpse into a new era of planet and star formation science.”



There are so many planet-sized objects revealed in the details of this image that he goes on to say that it gives him hope that the next generation of ground-based telescopes “will discover a wealth of smaller Earth-sized planets”.



The search for planets like the Earth is a current focus for astronomers. Although more than 3400 planets are known to exist beyond our solar system, none are so similar to Earth that they can be called Earth’s twin.



The planets found in this image are unlikely to be habitable because they do not orbit stars. Instead they are floating freely in space. They could have been pulled out of their home solar systems by the great gravitational forces at work in Orion, or they could have formed in isolation as the great nebula collapsed into the stars.

The collapse of a nebula into stars is similar to smashing a plate on the floor. There will be a small number of large pieces and a large number of small pieces. In Orion, there are a few large stars and – we now know from this image – a huge number of small, planet-size objects.

The name ‘planetars’ was once suggested for these celestial objects because they are the size of planets yet they follow orbits around the Galaxy like stars. The name didn’t catch on and astronomers now refer to them as free floating planets.

Also revealed in this image are a large number of objects larger that planets but smaller than stars. These are rather like larger versions of the gas planet Jupiter in our own solar system, but again they floating freely in space. Astronomers think of them as failed stars and call them brown dwarfs.

This image was taken by the HAWK-I infrared instrument on the European Southern Observatory’s Very Large Telescope.

In the northern hemisphere’s winter months, the nebula is visible to the naked eye as a faint smudge of light just beneath the three stars of Orion’s belt.

Stuart Clark’s new book is The Search for Earth’s Twin (Quercus). He spoke to Ian Sample about finding planets on Science Weekly.