\u201cHWO\u2019s primary mission is to search for signatures of life on planets orbiting other stars. To achieve this, HWO will need to observe many nearby star systems, sometimes for several days at a time,\u201d explained Mary Anne Limbach<\/a> of the University of Michigan.<\/p>\n During such events, starlight reflects off the star-facing side of the exoplanet. The researchers propose that if an Earth-sized moon passes behind the planet, effectively undergoing a lunar eclipse<\/a>, some of that reflected light could bounce off the moon\u2019s atmosphere and travel toward Earth.<\/p>\n Their simulations indicate that HWO could detect an Earth-like exomoon orbiting a Jupiter-sized exoplanet located 1 astronomical unit from its star. The signal, as explained in the study, would be observable from as far as 12 parsecs, or about 39 light-years away. The models also suggest sensitivity to moons as small as 0.5 times Earth\u2019s radius.<\/p>\n Why Giant Planets Remain Prime Targets<\/p>\n The researchers argue that habitable-zone gas giants should remain on HWO\u2019s target list. In the study, the authors wrote that:<\/p>\n \u201cExomoons are a place where we should think \u2018outside the box\u2019 about what HWO can find,\u201d emphasizing that the observatory\u2019s capabilities may extend beyond detecting Earth-sized exoplanets.<\/p>\n According to the study, lunar eclipses are highly sensitive events but may be time-inefficient for blind searches. Dedicated monitoring of large giant planets, the authors note, is likely to be scientifically productive. They also stress the need to plan how to characterize any candidate moons once detected.<\/p>\n This focus mirrors our own solar system, where the largest planets host the richest moon systems. Jupiter <\/a>and Saturn <\/a>alone account for dozens of satellites, including several considered potentially habitable.<\/p>\n The Unresolved Status of Exomoon Candidates<\/p>\n Despite multiple claims over the years, confirmed extrasolar satellite remain elusive. Several candidates continue to be studied, including Kepler-1625b I, Kepler-1708b I, the Kepler-90g moon candidate, the Kepler-80g moon candidate, and the WASP-49b moon candidate.<\/p>\n![\"Concept](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2026\/02\/Concept-of-NASAs-HWO-with-segmented-mirror-and-starshade-1200x793.jpg.webp.webp\")
Concept of NASA\u2019s HWO with segmented mirror and starshade. Credit: NASA Goddard Space Flight Center<\/p>\n![\"Simulated](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2026\/02\/Simulated-light-curve-of-an-Earth-like-exomoon-showing-the-dip-caused-by-a-lunar-eclipse-behind-a-Ju.webp\")
Simulated light curve of an Earth-like exomoon showing the dip caused by a lunar eclipse behind a Jupiter-sized planet. Credit: Researchgate<\/p>\n