Thackeray's Globules in IC 2944

Strangely glowing dark clouds float serenely in this remarkable and beautiful image taken with the NASA/ESA Hubble Space Telescope. These dense, opaque dust clouds - known as "globules" - are silhouetted against against the red glow of hydrogen gas and bright stars in the busy star forming region, IC 2944. These globules were first found in IC 2944 by astronomer A.D. Thackeray in 1950.

Although globules like these have been known since Dutch-American astronomer Bart Bok first drew attention to such objects in 1947, little is known about their origin and nature, except that they are generally associated with large areas of star-formation, called "HII regions" due to the presence of hydrogen gas.

Thanks to the remarkable resolution offered by the Hubble Space Telescope, astronomers can, for the first time, study the intricate structure of these globules. The globules appear to be fragmented, as if in the process of being torn apart. When radio astronomers observed the faint hiss from molecules within the globules, they realised that the globules are actually in constant, churning motion, moving supersonically among each other. This chaotic motion may be caused by the powerful ultraviolet radiation from the luminous, massive stars. These stars also heat the glowing hydrogen gas, causing it to expand against the globules, leading to their destruction. Despite their serene appearance, the globules may actually be likened to clumps of butter put onto a red-hot pan.