In 2025, we may detect the first signs of life outside our solar system.
This potential breakthrough is crucial The James Webb Space Telescope, 6.5 meters in diameter (JWST). Launched aboard an Ariane-5 rocket from Kourou, a coastal city in French Guiana, in 2021, JWST is our largest space telescope to date. Since it began collecting data, the telescope has enabled astronomers to observe some of the darkest objects in space, such as historic galaxies and black holes.
Perhaps more importantly, in 2022 the telescope also gave us the first glimpses of rocky exoplanets found in what astronomers call the habitable zone. This is the region around the star where temperatures are suitable for liquid water – one of the key ingredients of life as we know it – to exist on the planet’s rocky surface. These Earth-sized planets were discovered orbiting a diminutive red star called TRAPPIST-1a star 40 light-years away and one-tenth the mass of the Sun. Red stars are cooler and smaller than our yellow Sun, making it easier to detect Earth-sized planets orbiting them. However, the signal detected from exoplanets is usually weaker than the signal emitted by the much brighter host star. The discovery of these planets was an extremely challenging technical achievement.
The next step – detecting particles in planetary atmospheres – will be an even greater astronomical challenge. Every time a planet passes between us and its star – during a transit – the star’s airy is filtered through the planet’s atmosphere and hits molecules in its path, creating the spectral absorption features we can look for. These features are very challenging to identify. To do this, JWST will need to collect enough data from several planetary transits to suppress the signal from the host star and enhance molecular features in the incredibly slim atmospheres of rocky exoplanets (if you shrink these planets to the size of, say, an apple, at that scale its atmosphere would be thinner than the fruit peel). But with a space telescope as powerful as JWST, 2025 could be the year we can finally detect these molecular signatures.
However, detecting water on exoplanets TRAPPIST-1 is not our only chance to find life on distant exoplanets. For example, in 2024, JWST also revealed potential signs of the presence of carbon dioxide and methane in the atmosphere K2-18ba planet located 124 airy years from Earth. However, K2-18b is not a rocky Earth-like planet orbiting its star in the habitable zone. Instead, it is more likely to be a giant ball of gas with a water ocean similar to Neptune (albeit smaller in size). This means that if there is life on K2-18b, it may exist in a form completely different from life as we know it on Earth.
In 2025, JWST will likely shed more airy on these tantalizing discoveries and hopefully, for the first time in history, confirm whether life exists on alien worlds light-years away from our own.