Credit: NASA\/Laine Havens; Music credit: Building Heroes by Enrico Cacace [BMI], Universal Production Music<\/figcaption><\/figure>\n
\u201cWith Roman, we\u2019ll be able to turn existing artist\u2019s conceptions of the Milky Way into more data-driven models using new constraints on the 3D distribution of interstellar dust,\u201d said Catherine Zucker, an astrophysicist at the Center for Astrophysics | Harvard & Smithsonian<\/a> in Cambridge, Massachusetts.<\/p>\n Scientists know how our galaxy likely<\/em> looks by combining observations of the Milky Way and other spiral galaxies. But dust clouds make it hard to work out the details on the opposite side of our galaxy. Imagine trying to map a neighborhood while looking through the windows of a house surrounded by a dense fog.<\/p>\n Roman will see through the \u201cfog\u201d of dust using a specialized camera<\/a> and filters<\/a> that observe infrared<\/a> light \u2014 light with longer wavelengths<\/a> than our eyes can detect. Infrared light is more likely to pass through dust clouds without scattering.<\/p>\n Light with shorter wavelengths, including blue light produced by stars, more easily scatters. That means stars shining through dust appear dimmer and redder than they actually are.<\/p>\n By comparing the observations with information on the source star\u2019s characteristics, astronomers can disentangle the star\u2019s distance from how much its colors have been reddened. Studying those effects reveals clues about the dust\u2019s properties.<\/p>\n \u201cI can ask, \u2018how much redder and dimmer is the starlight that Roman detects at different wavelengths?\u2019 Then, I can take that information and relate it back to the properties of the dust grains themselves, and in particular their size,\u201d said Brandon Hensley, a scientist who studies interstellar dust at NASA\u2019s Jet Propulsion Laboratory in Southern California.<\/p>\n Scientists will also learn about the dust\u2019s composition and probe clouds to investigate the physical processes behind changing dust properties.<\/p>\n Clues in dust-influenced starlight hint at the amount of dust between us and a star. Piecing together results from many stars allows astronomers to construct detailed 3D dust maps. That would enable scientists like Zucker to create a model of the Milky Way, which will show us how it looks from the outside. Then scientists can better compare the Milky Way with other galaxies that we only<\/em> observe from the outside, slotting it into a cosmological perspective of galaxy evolution.<\/p>\n \u201cRoman will add a whole new dimension to our understanding of the galaxy because we\u2019ll see billions and billions more stars,\u201d Zucker said. \u201cOnce we observe the stars, we\u2019ll have the dust data as well because its effects are encoded in every star Roman detects.\u201d<\/p>\n The interstellar medium does more than mill about the Milky Way \u2014 it fuels star and planet formation. Dense blobs of interstellar medium form molecular clouds<\/a>, which can gravitationally collapse and kick off the first stages of star development. Young stars eject hot winds that can cause surrounding dust to clump into planetary<\/a> building blocks.<\/p>\n \u201cDust carries a lot of information about our origins and how everything came to be,\u201d said Josh Peek, an associate astronomer and head of the data science mission office at the Space Telescope Science Institute in Baltimore, Maryland. \u201cRight now, we\u2019re basically standing on a really large dust grain \u2014 Earth was built out of lots and lots of really tiny grains that grew together into a giant ball.\u201d<\/p>\n Roman will identify young clusters of stars in new, distant star-forming regions as well as contribute data on \u201cstar factories\u201d previously identified by missions like NASA\u2019s retired Spitzer Space Telescope<\/a>.<\/p>\n \u201cIf you want to understand star formation in different environments, you have to understand the interstellar landscape that seeds it,\u201d Zucker said. \u201cRoman will allow us to link the 3D structure of the interstellar medium with the 3D distribution of young stars across the galaxy\u2019s disk.\u201d<\/p>\n Roman\u2019s new 3D dust maps will refine our understanding of the Milky Way\u2019s spiral structure, the pinwheel-like pattern where stars, gas, and dust bunch up like galactic traffic jams. By combining velocity data with dust maps, scientists will compare observations with predictions from models to help identify the cause of spiral structure\u2014currently unclear.<\/p>\n The role that this spiral pattern plays in star formation remains similarly uncertain. Some theories suggest that galactic congestion triggers star formation, while others contend that these traffic jams gather material but do not stimulate star birth.<\/p>\n Roman will help to solve mysteries like these by providing more data on dusty regions across the entire Milky Way. That will enable scientists to compare many galactic environments and study star birth in specific structures, like the galaxy\u2019s winding spiral arms or its central stellar bar.<\/p>\nSolving Milky Way mystery<\/strong><\/h3>\n
![\"Animation](\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2025\/09\/wavelength-extinction-3d-v1.gif?w=800\")
<\/a><\/figure>Galactic life cycles<\/strong><\/h3>\n