Could a New Home Be Hidden Among the Stars?
As scientists map distant worlds, a tantalizing question persists: could humanity someday call another planet home? NASA has identified several potentially habitable exoplanets—rocky worlds and temperate climates that sit within their stars’ habitable zones. These are places where liquid water might exist, a crucial ingredient for life as we know it. Here are seven of the most discussed candidates and what makes them intriguing for a possible future of human exploration and, in the distant future, habitation.
1) Kepler-186f — Earth’s Twin in the Cygnus Constellation
Discovered by NASA’s Kepler mission, Kepler-186f is often called Earth’s twin due to its size and position in its star’s habitable zone. About 490 light-years away, this world is roughly 2.4 times the size of Earth and is believed to be rocky. Orbiting a sun-like star, it holds the potential for surface temperatures that could allow liquid water—a key factor for habitability. Kepler-186f is a landmark reminder that Earth-sized planets in temperate zones are common in our galaxy.
2) Kepler-452b — The Earth-like Neighbor
Kepler-452b, located about 1,402 light-years away in the Cygnus constellation, is about 60% larger than Earth and resides in the habitable zone of a star similar to our Sun. Its orbital period of about 385 days echoes Earth’s year, making it a compelling “Earth-like” candidate for habitability studies and long-term human exploration planning, even though its greater distance makes direct study challenging with current technology.
3) Kepler-442b — A Solid Candidate for Liquid Water
Kepler-442b is a super-Earth discovered in 2015, orbiting a cooler, K-type star roughly 1,196 light-years away. With an estimated size about 1.3 times that of Earth, this world sits in its star’s habitable zone and is considered a strong candidate to host oceans or lakes, depending on atmospheric conditions. Its distance and stellar properties make it a frequent subject of speculation about future exploration.
4) Kepler-62f — A Budget-Friendly Super-Earth Option
Kepler-62f is another promising super-Earth, about 1.4 times Earth’s size. It orbits Kepler-62 in the constellation Lyra, with a distance that places it well within the habitable zone. The planet’s radius suggests a potentially thicker atmosphere or surface conditions that could support liquid water, positioning it as a long-shot but plausible target for future habitability studies.
5) Proxima Centauri b — Our Closest Known Candidate
Discovered in 2016, Proxima Centauri b orbits the red dwarf star Proxima Centauri, the nearest star to the Sun, about 4.24 light-years away. With a mass near Earth’s size and an orbital period of roughly 11.2 days, this world sits within its star’s habitable zone despite orbiting a highly active star. Proxima Centauri b represents humanity’s most immediate potential neighbor in the search for habitable exoplanets.
6) TOI-700 d — A Red Dwarf’s Promising World
TOI-700 d, identified by NASA’s TESS mission in 2020, orbits a red dwarf approximately 101.4 light-years away. This rocky planet is in the habitable zone of its star and receives about 86 percent of the energy Earth receives from the Sun. Its relative proximity makes it a focal point for assessments of atmospheric composition and surface conditions that could sustain liquid water.
7) TOI-700 e and Other Companions — A System Worth Watching
While TOI-700 d is the most studied in its system, additional planets in the same system contribute to our understanding of planet formation and habitability around red dwarfs. The TOI-700 system illustrates how multiple worlds can coexist in a single stellar neighborhood, expanding the types of environments scientists evaluate when considering future human outposts beyond Earth.
What Does “Habitability” Really Mean?
Habitability is a spectrum, not a guarantee. A world might sit in the habitable zone yet possess a thick, opaque atmosphere, a frozen surface, or intense stellar activity that challenges life as we know it. Conversely, a planet slightly outside the conventional habitable zone could harbor niches where liquid water persists. For space agencies and private partners, the key is understanding atmospheric composition, geological activity, and potential shielding from stellar radiation—critical factors for long-duration human missions.
Looking Ahead
These seven exoplanets illustrate the diversity of environments that could someday become humanity’s homes. Each planet offers lessons about climate, geology, and potential biosignatures. While current technology limits rapid travel to these distant worlds, the quest drives advancement in propulsion, life support, and planetary science. In the coming decades, research, telescopic observations, and possibly interstellar probes will deepen our understanding of where life could endure and how humans might adapt to new, far-flung homes.
