Scientists caution against labeling exoplanets as “Earth-like” without solid evidence

Since the first exoplanet detections, astronomers have identified more than 6,300 alien worlds, ranging from scorching lava planets to frozen gas giants. Public fascination with finding a true Earth twin has led media outlets to repeatedly brand new discoveries as “Earth-like,” even when only size or orbital distance is known. The author highlights LHS 1140b, a planet orbiting a dim red dwarf about 49 light-years away, as an example of this trend.

Discovered by the MEarth project in 2017, the planet is roughly 1.73 × Earth’s diameter and 5.6 × its mass, giving it a density similar to Earth’s but a surface gravity about 1.8 g. Although it lies within the star’s habitable zone, its proximity to the star and likely lack of a strong greenhouse effect suggest it would be much colder than Earth, possibly a frozen water world with a thick atmosphere. The James Webb Space Telescope recently detected helium leaking from LHS 1140b, marking the first atmospheric detection for a rocky exoplanet, yet the data do not clarify the overall atmospheric makeup or surface conditions. The author concludes that overstating “Earth-like” qualities can mislead the public and recommends emphasizing both what is known and what remains uncertain about these diverse worlds.