Our galaxy, the Milky Way, is of the massive spiral variety, which means that it features two arms (four by some accounts) filled with stars. Measuring the distance to these stars is something that may seem simple at first, but which is actually very complicated, mostly because of the inherent uncertainties that existing models bring to the table. All that is about to change, as the first results of the Sloan Digital Sky Survey are starting to be made available. For almost a decade, astronomers have been using the 2.5 meter telescope at Apache Point Observatory, in New Mexico, to scout the skies and create a new map of our galaxy, that would allow astronomers to study its formation and evolution.

According to Technology Review, the largest difficulty that we have is the fact that we cannot be certain that other stars are indeed as far from us as we think they are. Existing measuring methods have a high degree of accurate approximation, which means that the distance is correctly appreciated to some extent. But no expert can put his or her life on a bet that these are actually the correct distances. At this point, Hertzprung-Russel diagrams (also known as the color magnitude diagrams) are the most widely used in establishing where another star is located.

The method relies on calculating an object's position based on a trait known as absolute magnitude or its inherent brightness. The difference between this value and the one obtained from the same object's observed magnitude, here on Earth, gives you an approximation of the distance between our planet and the study target. The problem with these diagrams was the fact that no one had until now measured the colors of most stars in the galaxy. This is very important because each star belongs to a different group, each with its own luminosity and brightness characteristics, that needed to be taken into account.

The Sloan Extension for Galactic Understanding and Exploration (SEGUE), a part of the larger survey, measured the color properties of more than 240,000 stars in our galaxy. Though this number looks impressive, it's only a small fraction of all celestial bodies out there. Using the diagrams, Jelte De Jong and colleagues, all from the Max-Planck Institute for Astronomy, in Germany, have developed a new 3D map of the Milky Way, based on the Sloan measurements. Each of the individual maps making up the document is a section through the galaxy, centered on the Sun. Experts hope that this will give them enough data to compile an accurate history of the formation and evolution of our galactic home.