We all read about the new exoplanet K2-18 b seemingly having molecules associated with life. I know it has to do with the local star’s light passing through the planet but that’s the extent of my knowledge.
We all read about the new exoplanet K2-18 b seemingly having molecules associated with life. I know it has to do with the local star’s light passing through the planet but that’s the extent of my knowledge.
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Life can produce a change in the gases in the atmosphere, light passing through the atmosphere will be impacted and so can potentially be detected on Earth.
Elements absorb certain frequencies of light, and these frequencies are always the same, and different for each element. By looking at which frequencies are missing, we can see what molecules, and in what proportions, the atmosphere is composed off.
They use spectroscopy. Light from the star is partially absorbed by the gasses in the atmosphere of a planet that travels in front of the start. By splitting up all the frequencies of light, they can see which frequencies are absorbed. Different molecules absorb different specific wavelengths of light, so you can determine which molecules must be present. If those molecules are things that are primarily or only made by living things, then you have evidence for life on that planet
Our telescopes like Hubble and JWST ‘see’ by absorbing light emitted/reflected from objects in the universe. They are extremely sensitive, and can detect even miniscule adjustments in light levels.
When we look at distant stars, the light coming from those stars will change slightly when one of that star’s planets passes in front of it. (Because the planet blocks some of the light, like a mini eclipse.) Our telescopes are able to detect that drop in light.
At the same time, light behaves differently when it passes through different gasses. By analyzing the change in light when a distant planet passes in front of a distant star, we can make a pretty good guess as to what gasses make up the atmosphere of that planet.
Some gasses only exist on Earth as a byproduct of life. Dimethyl sulfide is one such gas, and is produced by various algae in the ocean.
We just found a planet that seems to have an atmosphere with an enormous amount of dimethyl sulfide in it, and it was already theorized that this planet has an enormous hydrogen ocean.
Basically, we found a planet that we think has an ocean, and it also has light signatures indicating tons of ‘ocean life gasses’ in the atmosphere.
That doesn’t mean there is an ocean with life on the planet, but if there WAS an ocean with life on the planet, this is exactly what we would expect to see.
While others are explaining the methodology as requested, it’s important to note that exoplanet K2-18 b may not harbor life. The molecule dimethyl sulfide has been discovered on a lifeless comet, so there are non-biological ways to create this molecule. Such is science, despite media’s attempt to push the narrative.
afaik we can’t detect life…we can detect “signs of life”. things that might signify that life could be there.
in this particular case, they used light passing thru the atmosphere to detect a compound that on earth is only produced by life.
this does not mean there is life there. it means there may be life there. or there may be something humans haven’t discovered yet that produces the same compounds.
It’s basically a good guess based on what we can observe vs what we know to be true about Earth
Sadly today it’s 5 year trip to Jupiter and that’s only a few thousandths of a light year away – this find is 120 whole light years away that’s so many thousands of years travelling!