The form of our Milky Way galaxy

A New 'Hitchhiker's Guide' to the Milky Way

They should have just asked Ford Prefect. U.S. astronomers have discovered the Milky Way has just two major arms of stars, not the four arms of the current model. Led by Robert Benjamin of the University of Wisconsin-Whitewater, using the Spitzer Space Observatory infrared detectors the scientists based their conclusion on an evaluation of 800,000 images of an expansive swath of the Milky Way taken by NASA'a Spitzer telescope.

By means of new infrared imaging from Spitzer , NASA scientists declare our spiraled Milky Way galaxy is in reality made up of just two main arms. For decades, astronomers have mapped out the galaxy with four major arms. The two revised arms --Norma and Sagittarius--have been demoted to the humble status of minor arm, according to NASA.

Scientists have studied parts and divisions of the galaxy for many years, but they speak telescopes tuned to sense infrared light provide them the best picture of its outline since they can make a way through dust. Infrared images taken in the 1990s led them to determine the huge bar of creamy nougat stars in the center of the galaxy. Spitzer's new-fangled infrared shots, joined with software that calculates stellar density, designate that Norma and Sagittarius aren't as thick as astronomers had thought.

"They will keep revising the picture in the similar method that early explorers sailing in the region of the globe had to continue revising the maps," said Robert Benjamin of the University of Wisconsin at Whitewater, who presented the results at a press conference this week.

Casey Kazan via NASA