Led by Nicolas Nardetto of the Max Planck Institute for Radio Astronomy in Bonn, Germany, the team used observations by a spectrograph attached to a European Southern Observatory telescope in the mountains of Chile.

The scientists made high-precision observations of eight bright, pulsating stars known as Cepheids.

"The motion of Milky Way Cepheids is confusing," said Nardetto. "If the rotation of the galaxy is taken into account, the Cepheids appear to 'fall' toward the sun. " But he added, "If Cepheids truly move toward the sun, the Milky Way's rotational pattern would be more complex than currently predicted."

The scientists said their observations imply the rotation of the Milky Way is simpler than previously thought, and is symmetrical about an axis.

The complex research is to be published in the journal Astronomy and Astrophysics.