Hubble took the two composite images with its Advanced Camera for Surveys. They show the clusters in brilliant clarity, from a distance of about 200,000 light-years away. The clusters are roughly 65 light-years across.

Star clusters can be held together tightly by gravity, as is the case with densely packed crowds of hundreds of thousands of stars, called globular clusters. Or, they can be more loosely bound in irregularly shaped groupings of up to several thousands of stars, such as the open clusters captured in the Hubble images.

The stars in the clusters are all relatively young and born from the same cloud of interstellar gas, but they will remain together only for a limited time and gradually will disperse into space, pulled away by the gravitational tugs of other passing clusters and clouds of gas.

Most open clusters dissolve within a few hundred million years, while more tightly bound globular clusters can exist for billions of years.

Open star clusters make excellent astronomical laboratories. The stars may have different masses, but all are at about the same distance, move in the same general direction, and have approximately the same age and chemical composition. They can be studied and compared to find out more about stellar evolution, the ages of such clusters, and much more.

The Small Magellanic Cloud, which hosts the two star clusters, is the smaller of the two companion dwarf galaxies of the Milky Way named after the Portuguese seafarer Ferdinand Magellan (1480-1521). It can be seen with the unaided eye as a hazy patch in the constellation Tucana (the Toucan) in the Southern Hemisphere.

Both the Small and the Large Magellanic Clouds are rich in gas nebulae and star clusters. These irregular galaxies most likely have been disrupted through repeated interactions with the Milky Way, resulting in the vigorous star-forming activity seen throughout the clouds.

Astronomers think both NGC 265 and NGC 290 could owe their existence to such encounters with the Milky Way.

Hubble's ACS took the images in October and November 2004 through its F435W, F555W, and F814W (blue, green and red) filters.

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