Our Solar System‘s Milky Way neighborhood just went upscale. Astronomers using ultra-sharp radio vision determine, a more accurate position of our Planetary System, among 200 billion stars, in our Galaxy. The sun’s newly classified neighborhood — the Local Arm, as shown in this picture — is more prominent than previously supposed. Image © Robert Hurt, IPAC; Bill Saxton, NRAO/AUI/NSF
We reside between two major spiral arms of our home galaxy, in a structure called the Local Arm.
New research using the ultra-sharp radio vision of the National Science Foundation’s Very Long Baseline Array (VLBA) indicates that the Local Arm, previously thought to be only a small spur, instead is much more like the adjacent major arms, and is likely a significant branch of one of them.
Alberto Sanna, of the Max-Planck Institute for Radio Astronomy, said:
“Our new evidence suggests that the Local Arm should appear as a prominent feature of the Milky Way.”
Determining the structure of our own Galaxy has been a longstanding problem for astronomers because we are inside it. In order to map the Milky Way, scientists need to accurately measure the distances to objects within the Galaxy. Measuring cosmic distances, however, also has been a difficult task, leading to large uncertainties. The result is that, while astronomers agree that our Galaxy has a spiral structure, there are disagreements on how many arms it has and on their specific locations.
VLBA telescope locations. Image © NRAO/AUI
Trigonometric Parallax method determines distance to star or other object by measuring its slight shift in apparent position as seen from opposite ends of Earth’s orbit. Image © Bill Saxton, NRAO/AUI/NSF