![\"Galactic](\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2026\/05\/milky-way-zones-mkv.jpg\")
<\/a><\/figure>Most known exoplanets are located within a couple thousand light-years of Earth. But one of Roman\u2019s core surveys<\/a> will peer all the way through the Milky Way\u2019s galactic bulge, the central hub where stars are packed more densely than anywhere else, to the fringes of the far side of the galaxy.<\/p>\n Roman will monitor stars scattered throughout a deep slice of the galaxy to watch for any that change in brightness<\/a>. Some stars periodically dim as orbiting planets cross in front of, or transit<\/a>, them. Others temporarily appear to brighten as the gravity of an intervening star and orbiting planets magnify a farther star\u2019s light, thanks to a phenomenon called microlensing<\/a>.<\/p>\n These two methods tend to reveal very different types of planets. The transit method, which Roman will use to reveal around 100,000 worlds<\/a>, is best at finding gigantic, scorching worlds since they block the most starlight and transit more frequently.<\/p>\n Microlensing, which Roman will use to find more than 1,000 worlds, is better suited to finding planets with larger orbits, like those in our solar system, whose gravity can be more easily separated from the gravity of their host stars. Microlensing can find planets as small as Earth and Mars and can find them within their star\u2019s habitable zone and even farther out. Such planets are almost undetectable by other methods and are virtually unknown outside of our own solar system. Pairing the two techniques will help astronomers explore planet formation throughout the galaxy, including Earth\u2019s birthplace and beyond.<\/p>\n Today, our solar system is located about 27,000 light-years from the center of the Milky Way. However, scientists think it formed about 10,000 light-years closer in and then migrated out to its current position.<\/p>\n The Sun\u2019s chemical makeup is the primary clue. Most stars that form in the outskirts of the galaxy are low in heavy elements, which is a blanket term for any elements other than hydrogen and helium, which formed with the birth of the universe. Heavy elements are forged by stars, so they\u2019re more common in places that have seen successive generations of stars.<\/p>\n Stars in the galactic bulge are much older than those in the disk of the Milky Way and thus have a slightly different chemical mixture that is richer in elements like silicon, oxygen, and magnesium.<\/p>\n Those differences matter because planets form out of the same material as their host stars. Stars with different compositions may host planets that are different too, perhaps rockier or larger. It could even influence whether planets form at all, or how many coalesce with each star.<\/p>\n Astronomers have already seen hints of such connections nearby.<\/p>\n \u201cStars with more heavy elements tend to host more planets, especially giant ones,\u201d said Robby Wilson, a postdoctoral fellow at NASA Goddard, who led a study<\/a> about Roman\u2019s expected transiting planet yield.<\/p>\n By sampling completely different populations of stars and planets, Roman will take these studies to a whole new level. Astronomers may soon uncover how common planetary systems like our own are throughout the Milky Way.<\/p>\n \u201cRoman will be especially powerful because it will observe hundreds of millions of distant stars, letting scientists compare faraway planet populations to those found nearby,\u201d said Wilson. \u201cAll of that data will give us a lot to comb through, so we\u2019re prepping by creating synthetic data, detecting simulated planets, and using machine learning to filter out false positives. That way we\u2019ll be ready to go right away when real data comes pouring in.\u201d And since all Roman data will be publicly available, anyone can join the hunt for other worlds.<\/p>\n Scientists also could study the atmospheres of perhaps a few thousand of the transiting planets Roman finds.<\/p>\n \u201cRoman won\u2019t analyze atmospheres in the same in-depth way as missions like NASA\u2019s James Webb Space Telescope, but it will gather different information on a much larger scale,\u201d Wilson said.<\/p>\n While telescopes like Webb search for detailed chemical fingerprints on individual targets, Roman will measure temperature patterns and climate behavior for thousands of planets. The mission will create a big-picture statistical view of exoplanet atmospheres, which Webb could follow-up on for further study.<\/p>\n Roman\u2019s infrared heat vision will detect glowing \u201chot Jupiters.\u201d About as large as Jupiter, which is around 11 times as wide as Earth, hot Jupiters orbit their stars in only a few days. These worlds are warm enough to radiate a detectable amount of infrared light.<\/p>\n Planetary systems with transiting hot Jupiters can have two dimming episodes: one when they cross in front of the star, and a second smaller one when they pass behind it and the star blocks the planet\u2019s light.<\/p>\n \u201cThat secondary dip tells us how bright, and therefore how hot, the planet is,\u201d said Wilson. \u201cBy tracking how the planet\u2019s brightness changes over its orbit, Roman can also see differences between the day side and night side, and even detect shifts in where the hottest region is on the planet. That tells us about atmospheric winds and heat circulation.\u201d<\/p>\n \u201cNASA\u2019s now-retired Kepler mission’s survey of 100,000 stars revolutionized the field of exoplanets over a decade ago, and taught us that planets are even more common than stars in our galaxy,\u201d said Jorge Mart\u00ednez-Palomera, an astronomer at NASA Goddard who is helping prepare for Roman\u2019s exoplanet data. \u201cRoman’s galactic bulge survey will observe around 100 million stars and probe underexplored areas of our galaxy, which will provide a foundational dataset that will likewise revolutionize what we know about other worlds and our place in the universe.\u201d<\/p>\n To learn more about NASA’s Roman mission, visit:<\/p>\n https:\/\/nasa.gov\/roman<\/strong><\/a><\/p>\n Download high-resolution video and images from NASA\u2019s Scientific Visualization Studio<\/a><\/p>\n By Ashley Balzer<\/strong> Media contact:<\/strong><\/p>\n Claire Andreoli<\/a>Exploring Earth\u2019s birthplace<\/strong><\/h3>\n
<\/a><\/figure><\/a><\/figure>Otherworldly climates<\/strong><\/h3>\n
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NASA\u2019s Goddard Space Flight Center<\/strong><\/a>, Greenbelt, Md.<\/strong><\/p>\n
NASA\u2019s Goddard Space Flight Center<\/a>, Greenbelt, Md.
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