Scientists believe there is only one other planet in our galaxy that could be Earth-like.

It’s you and I, Kepler-442b.

What is it like for an alien exoplanet host to life as we know? It turns out, a lot.

A paper published last year claimed that there might be 300,000,000 planets in our galaxy that could be “potentially inhabitable.” However, new research published Monthly Notices contradicts this view.

This new analysis of exoplanets suggests that Earth-like conditions may not be possible on potentially habitable planets. It focuses on photosynthesis.

Although 4,422 exoplanets were discovered so far , only a few are believed to be habitable.

Photosynthesis is the process by which plants use sunlight, water, and carbon dioxide to produce oxygen and energy.

Because photosynthesis is crucial in creating complex biospheres like the one found on Earth, an exoplanet must develop an oxygen-based atmosphere to be habitable.

Launched later in the year, the James Webb Space Telescope will allow us to observe exoplanets’ atmospheres while they transit their stars. Their atmospheres will be revealed by the light that passes through them.

Photosynthesis, however, requires liquid water. Exoplanets must be at the right temperature to allow photosynthesis.

How many exoplanets of Earth-sized rocky size are there in the so-called “Goldilock’s Zone”?

This research suggests that there are not many.

Even among the few rocky exoplanets that are potentially habitable, none of them have the theoretical conditions for sustaining a photosynthesis-powered biosphere Earth-like.

Not all bad news is bad.

The study that measured the radiation (sunshine), each promising exoplanet received from its star revealed one planet that receives enough sunlight to support a large biosphere, as could be detected using JWST– Kepler-442b.


What do we know about Kepler-442b

Kepler-442b, a rocky planet with twice the mass as Earth, orbits a moderately bright orange dwarf star about 1,120 light-years away in the constellation Lyra.

The telescope’s existence was first announced in 2015, after it was discovered by the Kepler Space Telescope while transiting its parent star. In 2018, the telescope was retired.

This exoplanet, also known as KOI-4742.01 is approximately half the distance to its star than the Earth. It takes 112 days for the star Kepler-442 to orbit.

It is a “super Earth,” that, despite its name , aren’t Earth-like.

According to the study, stars with half the Sun’s temperature cannot support Earth-like biospheres. This is because they don’t provide enough energy within the right wavelength range.

This doesn’t necessarily mean that photosynthesis is impossible. However, there wouldn’t be enough plant species to support an Earth-like biosphere.

This is a setback for the search for life elsewhere in the galaxy, as 70% of the Milky Way’s stars are dim red dwarfs (also known M-dwarfs), which suggests that none of these stars–suggests the study–provide enough sunlight to allow significant photosynthesis to take place.

The study suggests that stars brighter and hotter than the Sun could power photosynthesis. However, these stars are not long enough to support complex life.

Professor Giovanni Covone, University of Naples lead author, said that red dwarfs are the most common star in our galaxy. This result suggests that Earth-like conditions may not be as common on other planets than we might think. “This study places strong constraints on the parameters space for complex life. It appears that the “sweet spot”, for hosting a rich Earth-like biosphere, is not as wide as it could be.

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