08/06/2023
🪐You’ve heard of Neptune. Now get ready for mini-Neptunes🪐
True to their names, mini-Neptunes are kind of like Neptune, but fun-sized. These exoplanets have thick, hazy (Neptune-like) atmospheres that can be difficult to peer through. Now Webb has lifted the curtain with the closest look yet at mini-Neptune GJ 1214 b.
Webb tracked its full orbit, allowing scientists to create a “heat map." This map showed a big change in temperature between the mini-Neptune’s day and night sides — only possible if its atmosphere is made of heavier molecules, such as water or methane. One theory is that GJ 1214 b’s atmosphere lost a lot of hydrogen over time, while another is that the planet may have started out as a “water world” farther away from its star.
There are no mini-Neptunes in our solar system. That has largely shrouded them in mystery, even though they are a common exoplanet type in our galaxy. Further observations will help us learn more about this planet and other mini-Neptunes!
Credit: Science - Eliza M.R.-Kempton et al.; Animation - Thomas Müller (HdA/MPIA)
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