The Largest Map of the Milky Way Yet

Neomi Lewis ‘21


Figure 1. The Milky Way and Andromeda Galaxies

The glaring image of the Milky Way is the rotating galaxy that usually comes to mind when individuals think about outer space. However, this typical image is no longer useful in studying bodies within the galaxy. Images of the Milky Way captured in visible light are obscured by dust and clouds. To remedy the situation, astronomers have used a 45 m radio telescope at the Nobeyama Radio Observatory to create the largest survey of the Milky Way to date.

The group worked for 1,100 hours from 2014 to 2017 to create an area as wide as 520 full moons with about three times the spatial resolution of previous maps. This is particularly difficult because good spatial resolution and wide-framed telescopes are generally mutually exclusive characteristics. Before maps like Nobeyama’s, it has been difficult to capture large-scale and small-scale data at the same time, leaving astronomers the task of filling in the gaps.

A map of this scale definitely gives astronomers insight into the larger structure of the Milky Way, including objects that we have little information about. At the same time, the telescope was able to obtain data on 3 different isotopes of carbon monoxide: 12CO, 13CO, and 18CO, which included details about the physical characteristics of the gas, such as temperature and density, as well as the distribution of the molecular gas and its motions. Studies of molecule gases like CO and molecular cloud cores provide further insight into star formation and the evolution of gases during processes like the birth of stars. Other analysis of data from galactic longitudes from 12 to 22 degrees led to the uncovering of giant molecular filaments, many of which were found around star-forming regions such as M17 and W51, suggesting an important role in star formation also.

The radio map obtained from this endeavor will be released in June 2018.  The map will provide valuable data for future studies of the Milky Way and act as a road map for other radio telescope and related objects perhaps even ultimately also for observations in infrared and other wavelengths, leading possibly to a variety of diverse, unique maps of the Milky Way in the future.


  1. The most detailed radio map of the milky way., (2018).
  2. Image retrieved from:

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