One of the most profound and enduring mysteries in scientific exploration remains unanswered: does extraterrestrial life exist, and if so, where might it be concealed? Now, a groundbreaking discovery by NASA has reignited the tantalising possibility that humanity is not alone in the cosmos.
A Distant World with Earth-Like Characteristics
The United States space agency has identified an exoplanet located approximately 146 light-years from Earth, designated HD 137010 b, which exhibits characteristics remarkably similar to our own planet. This rocky world might reside just within the outer boundaries of its star's 'habitable zone', a region where conditions could allow for the presence of liquid water on the surface and a suitable atmosphere to support life.
Challenges of a Cold Climate
However, any potential alien organisms inhabiting this distant planet would likely need to be exceptionally well-adapted to frigid conditions. NASA explains that although the star, HD 137010, shares a stellar type similar to our Sun, it is notably cooler and dimmer. This could result in a planetary surface temperature no higher than –90°F (–68°C). For context, the average surface temperature on Mars is approximately –85°F (–65°C), making HD 137010 b a potentially icy world.
Discovery Through Kepler Telescope Data
NASA's scientists made this significant finding using data collected by the Kepler Space Telescope. The detection stems from a single 'transit' event, where the planet was observed crossing the face of its host star, captured during Kepler's second mission, known as K2. While one transit might seem insufficient, it provided enough information for researchers to estimate the exoplanet's orbital period.
By analysing the time taken for the planet's shadow to traverse its star, the team calculated an orbital period of about 10 hours, compared to Earth's 24-hour day. Their models also indicate that the planet is probably freezing, though there remains a possibility that HD 137010 b could be a temperate or even a watery world. As NASA notes, this would require an atmosphere richer in carbon dioxide than Earth's.
Statistical Probabilities of Habitability
Based on atmospheric modelling, NASA estimates there is a 40 per cent chance the planet falls within the 'conservative' habitable zone and a 51 per cent chance it lies within the broader 'optimistic' habitable zone. Conversely, experts caution that the planet has roughly a 50–50 probability of being located entirely beyond the habitable zone.
The Path to Confirmation
To determine whether HD 137010 b is truly habitable, researchers plan to conduct follow-up observations, though they acknowledge this will be 'tricky'. The planet's orbital distance, similar to Earth's, means transits occur less frequently than for planets with tighter orbits, making such exoplanets particularly challenging to detect.
Confirmation may come from further observations by NASA's TESS (Transiting Exoplanet Survey Satellite), the successor to Kepler/K2, or from the European Space Agency's CHEOPS (CHaracterising ExOPlanets Satellite). Otherwise, gathering additional data might await the next generation of space telescopes.
Key Milestones in the Search for Extraterrestrial Life
Discovery of Pulsars (1967)
British astronomer Dame Jocelyn Bell Burnell first discovered a pulsar in 1967, detecting a radio pulsar. Initially, these rotating, highly magnetised neutron stars were thought to potentially originate from alien sources.
The 'Wow!' Radio Signal (1977)
In 1977, Dr Jerry Ehman observed a powerful 72-second radio signal from Sagittarius, writing 'Wow!' next to his data. This signal, 30 times stronger than background radiation, has fueled speculation about intelligent extraterrestrial origins.
Fossilised Martian Microbes (1996)
NASA and the White House announced that meteorite ALH 84001 contained traces of Martian microbes. However, subsequent debate questioned contamination and whether mineral structures mimicked microfossils.
Tabby's Star Behaviour (2005)
KIC 8462852, located 1,400 light-years away, dims unusually fast, once prompting theories of alien megastructures. Recent studies suggest a dust ring may explain the signals.
Exoplanets in the Goldilocks Zone (2017)
Astronomers discovered seven Earth-like planets orbiting dwarf star Trappist-1, 39 light-years away, with three potentially having conditions suitable for evolved life.
