JWST Has Shown It Can Detect Signs of Exoplanet Life

EPA

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Illustration of the James Webb Space Telescope, folded in an Ariane 5 rocket at launch.

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Nationalgeographic.co.id—In this universe, Earth is the only place known to have life. Until now, scientists are still trying to find out if there is life on other planets in this universe.

To detect life on distant planets, astrobiologists will study starlight that has interacted with the planet’s surface or atmosphere. If the atmosphere or surface is altered by life, the light may carry clues, called “biosignatures.”

For the first half of its existence, Earth had an atmosphere without oxygen, despite having simple single-celled life. Earth’s biosignature was very faint during this early era.

Earth’s biosignature changed abruptly 2.4 billion years ago when a new family of algae evolved. Algae use the process of photosynthesis to produce free oxygen – oxygen that is not chemically bound to other elements. Since then, Earth’s oxygen-filled atmosphere has left a strong biosignature that is easily detectable in light passing through it.

When light bounces off the surface of a material or passes through a gas, certain wavelengths of light are more likely to remain trapped on the surface of the gas or material than others. This selective trapping of wavelengths of light is what causes objects to have different colors.

Leaves are green because chlorophyll is very good at absorbing light in the red and blue wavelengths. When light hits a leaf, the red and blue wavelengths are absorbed, leaving most of the green light to bounce back into your eyes.

The pattern of light loss is determined by the specific composition of the material with which the light interacts. Because of this, astronomers can learn something about the composition of an exoplanet’s atmosphere or surface by, in effect, measuring the specific color of light emanating from a planet.

This method can be used to identify the presence of certain atmospheric gases associated with life, such as oxygen or methane, because these gases leave very specific signatures in light. This method can also be used to detect strange colors on the surface of planets.

On Earth, for example, chlorophyll and other pigments that plants and algae use for photosynthesis capture certain wavelengths of light. This pigment produces a distinctive color that can be detected using a sensitive infrared camera. If you see this color reflected off the surface of a distant planet, it could potentially indicate the presence of chlorophyll.

Telescope in outer space and on Earth

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