Confirmed exoplanet · Database record + computed analysis
Wolf 1061 c
A confirmed world orbiting Wolf 1061, 14.0 light-years away.
A super-Earth
1.66 Earth radii. Worlds between Earth and Neptune in size are the most common in the galaxy, yet our Solar System has none, which is why each one matters.
The orbit
Its year, one full orbit, takes just 17.9 Earth days. Orbiting this tightly around a cool star, it is very likely tidally locked: one hemisphere in permanent day, the other in permanent night.
Temperature and starlight
Its equilibrium temperature (the airless-world estimate) is about 26 °C. In the range where, with the right atmosphere, liquid water is conceivable; a real atmosphere could shift the true surface figure a lot (Earth's equilibrium value is −18 °C, yet we average +15 °C). It receives 1.30 times Earth's starlight, the same order as our own world.
Its sun
Its star is a red dwarf (3,342 K surface), type M3.5: small, dim, flare-prone, and destined to outlive the Sun many times over. It shares the system with 2 other known planets.
How far is that, really?
At 14 light-years, tonight's light from this system left it around the year 2011. That is close by galactic standards, which makes it a prime target for follow-up telescopes. A Voyager-speed probe would need roughly 248,475 years to get there.
How we found it
It was found by the radial-velocity method: the planet's gravity swings its star in a small circle, and that wobble shows up as a rhythmic Doppler shift in the starlight. The wobble's size gives the planet's minimum mass. The discovery was announced in 2015 from La Silla Observatory.
Everything above is computed from the archive’s measured values for this planet. Where a quantity is missing, the statement is omitted rather than guessed.
The deep dive
Researched for the Atlas from Wikipedia — Wolf 1061c (3,181 characters read) · updated Sep 20, 2026
01 A Super-Earth at the Inner Habitable Edge
Wolf 1061 c earns the label 'super-Earth' because its minimum mass is about 3.4 times that of Earth — too small to be a gas giant, yet substantially larger than our own world. Its radius has never been directly measured, but models predict a value of roughly 1.6 times Earth's radius. That combination of mass and size places it in a class of planets that simply does not exist in our own solar system, sitting somewhere between the rocky terrestrial planets and the ice giants like Neptune. What makes its location especially striking is that its orbital distance of 0.084 AU puts it right at the inner edge of Wolf 1061's habitable zone, the narrow band where liquid water could theoretically persist on a surface. Being at the inner edge is a double-edged situation: the planet receives enough warmth to avoid a global deep-freeze, but it also teeters close to the threshold where a runaway greenhouse effect could strip away any oceans entirely.
02 How Ten Years of Starlight Revealed a World
The discovery of Wolf 1061 c was announced on 17 December 2015, but the detective work behind it stretched back a full decade. Astronomers mined ten years of archival spectra collected by the HARPS spectrograph, an instrument attached to the ESO 3.6 m Telescope at the European Southern Observatory at La Silla, Chile. HARPS — the High Accuracy Radial velocity Planet Searcher — detects planets by measuring the tiny Doppler wobble they induce in their host star's light as they orbit. Because no single observation night could confirm such a subtle signal, the long baseline of archived data was essential. The planet was never seen directly; instead, its presence was inferred from the rhythmic tug it exerts on Wolf 1061 every 17.9 days. This archival approach demonstrates how patient, systematic data collection pays dividends years after the original observations were made, turning old starlight into new discoveries.
03 Wolf 1061: A Star That Burns for Eons
The host star, Wolf 1061, is a red dwarf with a mass of only 0.25 solar masses and a radius of just 0.26 solar radii — a faint, cool ember compared to our Sun. Its surface temperature is 3,380 K, less than 60 percent of the Sun's 5,778 K, which is why it glows in deep red rather than yellow-white. With an apparent magnitude of 10.1, it is far too faint to see with the naked eye; you would need at least binoculars to spot it in the constellation Ophiuchus. The star's age is poorly constrained, with estimates placing it somewhere in the range of a few billion years. Perhaps the most jaw-dropping characteristic of red dwarfs like Wolf 1061 is their longevity: because they burn fuel so slowly, they can remain on the main sequence for 400 to 500 billion years — 40 to 50 times longer than the Sun's total expected lifespan of roughly 10 billion years.
04 An Orbit Tighter Than Mercury's
Wolf 1061 c completes one full orbit every 17.9 days at a distance of just 0.09 astronomical units from its star — for context, Mercury, the innermost planet in our solar system, orbits at 0.38 AU, more than four times farther from the Sun. Despite this extreme closeness, the planet is not roasting, because its host star emits less than 1 percent of the Sun's total luminosity. That feeble energy output is precisely what defines where the habitable zone sits: much closer to the star than it would be around a solar-type star. The habitable zone of Wolf 1061 spans roughly 0.073 to 0.190 AU, a range that looks tiny compared to our own solar system's habitable zone, which astronomers approximate at 0.5 to 3.0 AU. Wolf 1061 c, sitting at 0.084 AU, occupies the warm inner portion of that zone.
05 Tidally Locked: A Planet of Eternal Day and Night
Because Wolf 1061 c orbits so close to its star, gravitational forces are thought to have long ago synchronized its rotation with its revolution — a condition called tidal locking. One hemisphere would be locked in permanent blazing daylight, the other in permanent freezing darkness. The equilibrium temperature of the planet is calculated at 223 K, which is negative 50 degrees Celsius, slightly warmer than Mars's equilibrium temperature but still deeply cold by Earth standards. That global average, however, masks potentially enormous regional extremes between the two locked hemispheres. The terminator line — the boundary separating the lit and dark sides — has been proposed as a zone where temperatures might be more moderate. Furthermore, if Wolf 1061 c possesses a sufficiently thick atmosphere, circulation could redistribute heat from the day side toward the night side, broadening the potentially livable region considerably beyond just the terminator.
06 The Runaway Greenhouse Question Deeper
A 2017 study cast serious doubt on the habitability picture for Wolf 1061 c, concluding that the planets in this system are unlikely to host any surface water. The researchers placed Wolf 1061 c within the Venus zone of its host star — the orbital region where a planet receives enough stellar radiation to trigger a runaway greenhouse effect, similar to what transformed Venus from a potentially habitable world into the scorching, cloud-choked planet it is today. In a runaway greenhouse, water vapor itself acts as a potent greenhouse gas; as the atmosphere warms, more water evaporates, which traps more heat, which evaporates more water, in an escalating cycle that eventually boils off any oceans. If this hypothesis is correct, Wolf 1061 c may be a rocky, desiccated world despite sitting technically within the habitable zone. The study highlights a recurring tension in exoplanet science: the habitable zone defines where liquid water is possible in principle, but it does not guarantee that a planet's actual atmospheric evolution led to that outcome.
07 A Triple-Planet System Around One Red Dwarf
Wolf 1061 c is the middle planet in a three-planet system, the second in order of distance from its host star. The existence of multiple planets orbiting the same red dwarf is scientifically significant because it suggests that planet formation around low-mass stars is common, not exceptional. The gravitational interactions among the three planets could influence the long-term orbital stability and even the climatic evolution of Wolf 1061 c over billions of years. While the article does not detail the other two planets, the multi-planet architecture means Wolf 1061 c does not orbit in isolation; it shares its stellar neighborhood with companions whose gravitational nudges may subtly reshape its orbit over geological timescales. Red dwarf systems like this one have become central targets in the search for life elsewhere, precisely because these stars are the most numerous in the galaxy and some of their planets orbit within the habitable zone.
08 The Closest Potentially Habitable World — For a While
When Wolf 1061 c was announced in December 2015, it held the title of the closest known potentially habitable exoplanet to Earth, at a distance of 14.1 light-years. That record has since been broken by several other discoveries, but the moment was significant: it demonstrated that habitable-zone planets were not rare anomalies confined to the distant reaches of the galaxy but could be found practically on our cosmic doorstep. At 14.1 light-years, Wolf 1061 c is close enough that it falls within the list of our nearest stellar neighbors, a region of space that has become increasingly populated with confirmed exoplanet discoveries as detection technology improves. The fact that such a planet exists this close raises the statistical probability that habitable-zone worlds are extraordinarily common throughout the Milky Way, even if Wolf 1061 c itself turns out to be inhospitable.
09 What the Equilibrium Temperature Really Tells Us Deeper
The equilibrium temperature of Wolf 1061 c is given as 223 K, equivalent to negative 50 degrees Celsius or negative 58 degrees Fahrenheit. This figure is calculated by balancing the stellar energy the planet absorbs against the energy it radiates back into space, assuming a certain reflectivity and no atmospheric greenhouse effect. The result is described as slightly higher than that of Mars, whose equilibrium temperature is similarly below freezing. However, equilibrium temperature is a simplified theoretical value. Earth's own equilibrium temperature would be well below freezing without its greenhouse atmosphere, yet the actual surface averages a life-friendly 288 K. A planet's true surface temperature depends critically on atmospheric composition, pressure, and dynamics — none of which are yet measured for Wolf 1061 c. The equilibrium temperature therefore functions as a baseline starting point rather than a prediction of real surface conditions, and real habitability could be either warmer or cooler depending on atmospheric factors that remain entirely unknown.
10 Why HARPS Was the Right Tool for This Search Deeper
The discovery relied on HARPS, the High Accuracy Radial velocity Planet Searcher, mounted on the ESO 3.6 m Telescope at La Silla, Chile. HARPS works by detecting the radial velocity signal of a planet — the tiny shift in a star's spectral lines caused by the gravitational tug of an orbiting world. For a planet the mass of Wolf 1061 c, these shifts are extraordinarily small, requiring an instrument capable of measuring velocities to within a meter per second or better. The fact that ten full years of archival spectra were needed underscores both the subtlety of the signal and the cumulative power of long-term monitoring programs. La Silla's dry, high-altitude site in the Atacama Desert region of Chile provides the stable atmospheric conditions that precision radial velocity work demands. The Wolf 1061 system's relative closeness at 14.1 light-years also helped: nearer stars appear brighter and produce higher signal-to-noise spectra, making the radial velocity wobbles slightly easier to extract from the data.
11 Open Questions About This Nearby World Deeper
Despite being one of our nearest planetary neighbors, Wolf 1061 c leaves many of its most fundamental properties uncertain or entirely unknown. Its radius has never been measured — the predicted value of about 1.6 Earth radii is a model estimate, not an observation. Without a measured radius, the planet's density and therefore its bulk composition remain unconstrained: it could be predominantly rocky, water-rich, or something else entirely. The host star's age is described as poorly constrained, which matters enormously for habitability since stellar flare activity tends to be higher in younger red dwarfs and could erode planetary atmospheres. Whether Wolf 1061 c has any atmosphere at all is unknown, and without atmospheric data the question of surface habitability cannot be resolved. The 2017 Venus-zone hypothesis and the tidal-locking scenario each represent plausible but not confirmed outcomes. Resolving these questions will likely require next-generation telescopes capable of characterizing the atmospheres of planets around nearby red dwarf stars.
About this record
The measured values come from the NASA Exoplanet Archive, and any missing value has not been determined yet; the Atlas never fills gaps with guesses. More standout worlds: Proxima b, TRAPPIST-1e, K2-18 b, 55 Cancri e, and the detection methods that found them all.