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AlphaDrac t1_jdwfp7n wrote

Reply to comment by nmfpriv in James Webb Space Telescope finds no atmosphere on Earth-like TRAPPIST-1 exoplanet by locus_towers

In order to measure a planet’s atmosphere Webb needs to watch the planet transit it’s star (which provides light that filters through its atmosphere). The wavelengths of filtered light then tell us about the atmosphere (or lack thereof in this case).

This planet just happened to be transiting first, I’m sure they’ll look back and observe the others in the system when it’s their turn.

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karlou1984 t1_jdx07ok wrote

Shouldn't be that long hopefully. I thought the orbital time is like 21 days max for these planets, some a lot shorter.

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AlphaDrac t1_jdy6mhv wrote

You may also have to consider the orbital planes of the planets. Now I really haven’t looked up anything deep about the Trappist system, but it may be like ours where planets orbit on similar planes, but not the same one. So while each orbital period is relatively short, it might take longer to get ones with good alignment between us and their star. Again, that’s just me guessing. I don’t have time to google it right now

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remchien t1_jdya4ce wrote

While usually true, in this case they used MIRI to measure the amount of missing heat when the planet was behind the star as opposed to next to it. A secondary eclipse instead of a transit. They can then make assumptions about the atmosphere with that measured temperature and the fact that it is a tidally locked planet.

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