Democritus was the first to claim that the Milky Way consisted of distant stars, but it was William Herschel in 1785 that made the first map of the Milky Way. Herschel was the first to study and measure the distribution of stars in space, and when he counted the stars he came to a conclusion that they were grouped in a huge disk formation. It is believed that this disk–our Milky Way Galaxy–is about 100,000 light years from tip to tip; however, recent evidence may suggest that it could be about 50 percent larger than we initially ever thought.
Research led by Rensselaer Polytechnic Institute Professor Heidi Jo Newberg suggests that the Milky Way disc is contoured into several concentric ripples. Newberg says, “[in] essence, what we found is that the disk of the Milky Way isn’t just a disk of stars in a flat plane–it’s
corrugated. As it radiates outward from the sun, we see at least four ripples in the disk of the Milky Way. While we can only look at part of the galaxy with this data, we assume that this pattern is going to be found throughout the disk.”
This study revisits data from the Sloan Digital Sky Survey–a 2002 survey that established a presence of bulging rings beyond the known plane of our galaxy. These bulging rings are now believed to be part of the galactic disk. If this is the case then it extends the known width of the Milky way from 100,000 light-years across to around 150,000 light-years across.
According to Yan Xu, a scientist at the National Astronomical Observatories of China and lead author of the paper, “[going] into the research, astronomers had observed that the number of Milky Way stars diminishes rapidly about 50,000 light years from the center of the galaxy, and then a ring of stars appears at about 60,000 light years from the center. What we see now is that this apparent ring is actually a ripple in the disk. And it may well be that there are more ripples further out which we have not yet seen.”
These findings were published in Astrophysical Journal under the title “Rings and Radial Waves in the Disk of the Milky way.” Here is a video of Professor Heidi Jo Newberg explaining the corrugated Milky Way galaxy.