Science Spin 48 September 2011 | Page 41

Orion Nebula The hubble Space Telescope has captured the most detailed image yet of the star forming Orion Nebula region. More than 3,000 stars are in this picture, a composite of 520 images obtained between 2004 and 2005. The Orion Nebula is 1,500 light years away from earth. Observations of this region from eSA’s herschel farinfrared instruments have shown the presence of molecular oxygen, the first time that these molecules have been detected in space. All the oxygen that had been detected before was in atomic form, single unattached atoms, rather than the molecular O2 form that we breathe. even in its atomic form, the low concentration of oxygen has perplexed scientists who calculate that its presence should be much greater. Oxygen is the third most abundant element in the Universe, yet herschel’s instruments recorded that every molecule of oxygen was outnumbered by a million of hydrogen. One possible explanation for this apparent shortage is that the oxygen atoms freeze into dust grains, and as water ice they are effectively hidden. Although this has not yet been proved, that ice could evaporate in warmer regions, allowing molecular oxygen to form.