Though no more than several times the mass of Earth, their hydrogen/helium atmospheres are so bloated they are nearly the size of Jupiter.
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To the amazement of the Hubble team, they found the spectra of both planets not to have any telltale chemical signatures.
The good news is that all is not lost for determining the atmospheric composition of these two planets.
HUH?
Apparently these planets have just helium and hydrogen, in a slushie-like mixture, no other chemical elements to make stuff, at least not enough to detect. No carbon, no hydrocarbons, no methane, no ammonia, etc.................