Several studies have shown that just 4 percent of the universe is observable matter. Dark matter makes up 23 percent. The bulk of the universe's mass-energy budget is an even more mysterious thing called dark energy.

In the new study, which confirms these numbers, researchers examined the motion of about 3,000 small galaxies that each orbited a larger, brighter galaxy. Scientists know how a given amount of mass should orbit another object of a certain mass. The mechanics of this is well understood in our solar system, for example, where dark matter is not a factor in the travels of planets around the Sun.

On larger scales, however, concentrations of dark matter force gravitational alliances between galaxies that can be noted based on the distance between the galaxies and the speed with which they orbit each other.

"Our results imply the presence of dark matter," lead researcher Francisco Prada said in a statement.

Prada works at the Max Planck Institute for Astronomy in Germany and the Instituto de Astrofisica de Canarias in Spain. His team used data from the Sloan Digital Sky Survey.

The study "is important because it is a direct measurement of some of the properties predicted for dark matter," said one of Prada's colleagues, Anatoly Klypin of New Mexico State University.

The finding is not surprising. Other recent studies using different methods have reached the same conclusion. What's left now is for astronomers to figure out what dark matter actually is.

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