By Casey Frye, CCNN Writer
Our galaxy, the Milky Way, is a mega spinning spiral of 100-400 billion stars and planets. The disk portion of the galaxy is 100,000 lightyears wide, and since light travels 186,000 miles a second, you can just imagine how far light would travel in 100,000 years. However, the Milky Way goes way beyond its disk, and is surrounded by a halo of stars that’s at least 500,000 lightyears away. In this outermost region, astronomers recently located the farthest known stars in the galaxy!
The two burning orbs are known as ULAS J0744+25 and ULAS J0015+01, and are about 775,000 and 900,000 lightyears from our planet, respectively. “The distances to these two stars are almost too large to comprehend,” said the lead author of the study, John Bochanski of Haverford College in Pennsylvania. “To put it in perspective, when the light from ULAS J0015+01 left the star, our early human ancestors were just starting to make fires here on Earth.”
In order to find the furthest possible stars, scientists focused on locating cool red giants, which are stars that burn 10,000 times brighter than regular red giants. Even though about 70% of the Milky Way’s star population is made up of red giants, the cool ones are ultra-rare. Fortunately, their brightness makes them easy to spot! Bochanski explains, “It really is like looking for a needle in a haystack. Except our haystack is made up of millions of red dwarf stars.”
Featured image courtesy of NASA. Image of ULAS J0744+25 star courtesy of Visualization Software: Uniview by SCISS Data: SOHO (ESA & NASA), John Bochanski (Haverford College) and Jackie Faherty (American Museum of Natural History and Carnegie Institute’s Department of Terrestrial Magnetism).