We have counted roughly 6,000 worlds beyond our solar system, but the list begins and ends with caveats: most are unlike Earth, and very few orbit stars like our Sun. “We've found 6,000 planets, but none of them are like Earth,” said Aurora Kesseli, an astronomer at Caltech who helps maintain NASA’s Exoplanet Archive. The next three decades, she and many colleagues say, will be devoted to changing that.

The near term will see a mix of complementary approaches. In 2028, the China National Space Administration plans to launch the Earth 2.0 mission to the Sun-Earth Lagrange 2 point to look for planetary transits—tiny, periodic dips in starlight caused when planets cross in front of their host stars. The L2 vantage point offers thermal stability and uninterrupted viewing that are crucial for the ultra-precise photometry needed to detect Earth-sized planets around distant Sun-like stars.

Meanwhile, the James Webb Space Telescope, operating from the same general neighborhood, has opened a new era of atmospheric characterization. Webb can probe the atmospheres of some habitable-zone worlds, but those are predominantly planets orbiting red dwarf stars—cool, small stars that exaggerate transit signals and differ markedly from the Sun in temperature, activity and spectral energy. Those differences complicate efforts to extrapolate habitability, and Webb lacks the starlight suppression and long-wavelength sensitivity to image a true Earth analog around a Sun-like star.

To reach that goal, the community is pinning its hopes on a later-generation observatory. The Habitable Worlds Observatory, a NASA flagship concept now under development, is slated for the 2040s and is being designed specifically to directly image Earth-sized planets around Sun-like stars and take spectra of their atmospheres. Direct imaging—blocking or subtracting a star’s blinding light to reveal a faint planet—requires technological feats of starlight suppression and stability that exceed current capabilities, but it is the clearest path to detecting Earth-like reflected light and searching for biosignatures such as oxygen or methane in the right combinations.

The scientific stakes are high and the technical challenges stark. Detecting and confirming an Earth twin requires sensitivity to flux ratios of roughly one part in ten billion and long-term monitoring to establish orbital periods and atmospheric composition. False positives—abiotic processes that mimic biological signatures—will demand rigorous cross-checks and conservative interpretation. The financial and political dimensions are also significant: multi-decade, multi-billion-dollar projects require sustained funding and international coordination during periods of shifting priorities.

Experts emphasize measured expectations alongside excitement. The next decade of transit surveys and atmospheric studies will expand the catalog of candidate habitable-zone planets, informing target lists for direct imagers in the 2040s. “If we want to see an actual Earth-like planet around a sun-like star, the best thing is going to be the Habitable Worlds Observatory,” Kesseli said.

The hunt for an Earth twin is as much a technological race as a scientific quest. Success would reshape our understanding of life’s prevalence, the architecture of planetary systems and the place of Earth in the cosmos. Failure, or a long silence, would be equally consequential, forcing a reckoning about the uniqueness of our planet and the future of exploratory priorities. Either way, the next 30 years will test our instruments—and our imagination.