Do Galaxies Rotate at Different Speeds?

Although space still contains countless mysteries, researchers have recently discovered a remarkably universal truth about disk galaxies -- they all take about one billion years to complete a full rotation. According to the International Centre for Radio Astronomy Research (ICRAR), it doesn't matter how many stars or planets a galaxy contains. The recent ICRAR finding about the uniform nature of rotation will help cosmologists better understand how galaxies operate.

Universal truths:

• Everything in space spins -- even as we orbit around the Sun, it rotates around the center of our galaxy; it takes about 225 million years to complete a full circle.
• The largest known galaxy is IC 1101, which has about 100 trillion stars.
• The Milky Way Galaxy is estimated to contain between 100 and 400 billion stars, with a diameter between 100,000 and 150,000 light-years.