Inverse by Chris Impey, Daniel Apai 7/25/2022
The best ways to find life using the Webb telescope, according to two astronomers
The ingredients for life are spread throughout the universe. While Earth is the only known place in the universe with life, detecting life beyond Earth is a major goal of modern astronomy and planetary science.
We are two scientists who study exoplanets and astrobiology. Thanks in large part to next-generation telescopes like Webb, researchers like us will soon be able to measure the chemical makeup of atmospheres of planets around other stars. The hope is that one or more of these planets will have a chemical signature of life.
Looking for biosignaturesTo detect life on a distant planet, astrobiologists will study starlight that has interacted with a planet’s surface or atmosphere. If the atmosphere or surface was transformed by life, the light might carry a clue called a “biosignature.”
For the first half of its existence, Earth sported an atmosphere without oxygen, even though it hosted simple, single-celled life. Earth’s biosignature was very faint during this early era.
That changed abruptly 2.4 billion years ago when a new family of algae evolved. The algae used a process of photosynthesis that produces free oxygen — oxygen that isn’t chemically bonded to any other element. From that time on, Earth’s oxygen-filled atmosphere has left a strong and easily detectable biosignature on the light that passes through it.
When light bounces off the surface of a material or passes through a gas, certain wavelengths of the light are more likely to remain trapped in the gas or material’s surface than others. This selective trapping of wavelengths of light is why objects are different colors. Leaves are green because chlorophyll is particularly good at absorbing light in the red and blue wavelengths. As light hits a leaf, the red and blue wavelengths are absorbed, leaving mostly green light to bounce back into your eyes.
More:
https://www.inverse.com/science/webb-and-aliens
