The mass of our Milky Way galaxy has been estimated to be about 700 billion times that of our Sun, say researchers who developed a new method to overcome the galactic challenge. The Sun has a mass of two nonillion (that is 2 followed by 30 zeroes) kilograms, or 330,000 times the mass of Earth. "And our galaxy is not even the biggest galaxy," said Gwendolyn Eadie from McMaster University in Canada. Measuring the mass of our home galaxy, or any galaxy, is particularly difficult, researchers said. A galaxy includes not only stars, planets, moons, gases, dust and other objects and material, but also a big helping of dark matter, a mysterious and invisible form of matter that is not yet fully understood and has not been directly detected in the lab. Astronomers and cosmologists, however, can infer the presence of dark matter through its gravitational influence on visible objects. Eadie, a PhD candidate in physics and astronomy at McMaster, used the velocities and positions of globular star clusters that orbit the Milky Way to study the mass of our galaxy and its dark matter component. The orbits of globular clusters are determined by the galaxy's gravity, which is dictated.