how we detect water in the atmosphere of a planet 110 light years away.
In: Technology
A star produces all colors of light (in different brightnesses depending on temperature). If you put this light through a prism you get a rainbow.
But this rainbow has dips in how bright it is depending on what it is made of. Hydrogen has dips at red (656nm), aqua (486nm), blue (434nm), and violet (410nm) for instance.
Every element or molecule has these kinds of spectral lines and they are unique. When it is hot and by itself these lines are bright (emmision spectra). When these molecules are blocking something brighter (like a star) they appear dark (absorption spectra).
When the planet is not in front on the star you measure the brightness of each color to establish a baseline. You then do this when the planet is in front of the star. Any new dark lines tell you what gasses are present on the planet.
Latest Answers