An alien world seven times the size of Jupiter has been found in a distant star system.
Astronomers detected clouds of carbon monoxide and water vapour around the huge gassy planet, orbiting a star 130 light years away.
The study is the most detailed yet of the atmosphere of an "exoplanet".
In future, scientists hope to use similar techniques to uncover signatures of life in the atmospheres of Earth-like worlds.
The planet, known as HR 8799c, has seven times the mass of Jupiter and is one of four similar planets distantly orbiting the star.
Observations suggest the solar system was created in a similar way to our own, with gas giants forming far away from their parent star and smaller, rocky planets closer in.
If this model is correct, there could be as-yet undetected Earth-like planets waiting to be found.
"The results suggest the HR 8799 system is like a scaled-up Solar System," said Dr Quinn Kanopacky, one of the astronomers from the University of Toronto in Canada.
Light wavelength "colours" act like fingerprints for different elements. By studying the light from a distant planet, scientists can make assumptions about what elements are contained in its atmosphere.
The presence of oxygen's cousin ozone or carbon dioxide, for instance, could indicate that a world harbours life.
Because HR 8799c is so big and far out - about the same distance from its star as Pluto is from the Sun - astronomers were able to image it directly rather than infer its presence.
The observations were made using the Keck II 10-metre telescope in Hawaii, one of the two largest optical telescopes in the world.
Dr Bruce Macintosh, from the Lawrence Livermore National Laboratory in California, US, one of the co-authors of the research published in the journal Science, said: "This is the sharpest spectrum ever obtained of an extrasolar planet. This shows the power of directly imaging a planetary system. It is the exquisite resolution afforded by these new observations that has allowed us to really begin to probe planet formation."