Using mostly Hubble Space Telescope data, Mr. Bridges and Mr. Forbes examined old star clusters within the Milky Way galaxy. From the research they compiled the largest ever high-quality database to record the age and chemical properties of each of these clusters.

"We looked at all the data we could find. The best data are from the Hubble Telescope because it has the best imaging," Bridges says. "We looked at the ages and the amounts of heavy elements in these clusters, which can be measured from their stars."

The researchers' work also suggests that the Milky Way may have swallowed-up more dwarf galaxies than was previously thought. They found that many of the foreign clusters originally existed within dwarf galaxies -- 'mini' galaxies of up to 100 million stars that sit within our larger Milky Way.
The study suggests that there are more of these accreted dwarf galaxies in our Milky Way than was thought.

When the public will know more about it - it's the million dollar question.