Exoplanets in 3D: Interpreting 3D planets using 1D spectra

太阳系中行星的卫星图像揭示了动态变化的世界。木星的两极现在被认为是出人意料的蓝色，与赤道形成鲜明对比，而且这个大红斑正在逐渐缩小。最近，我们也开始更多地了解围绕其他恒星运行的行星--系外行星。研究系外行星是令人兴奋的，因为它为太阳系行星的演化提供了背景，但也涉及几个挑战。我们很少能直接观察到系外行星，因为恒星要大得多，也更亮。相反，当行星从前面经过时，我们测量来自母星的光量的下降。气体和云层粒子吸收和散射特定颜色或波长的光，因此通过精确测量行星在每个波长上阻挡的光量，我们可以识别行星大气中物质的独特指纹--所有这些都不需要看到行星！然而，有一个问题：我们只能获得整个地球可见大气的平均测量结果，这并不均匀，而且随着时间的推移而变化。为了真正将系外行星与太阳系世界进行比较，我们需要了解这个平均测量值实际上代表了什么。我的目标是利用光穿过大气层的计算模型，研究如何利用这些测量来最好地研究3D、时变、多云的系外行星大气。我将把模型与新的詹姆斯·韦伯太空望远镜的数据进行比较，该望远镜将于2021年发射，将提供迄今最详细、最精确的系外行星观测。

Satellite images of the planets in our Solar System reveal dynamic, changing worlds. Jupiter's poles are now known to be unexpectedly blue, contrasting with the equator, and the great red spot is gradually shrinking. Recently, we have also started to find out more about planets orbiting other stars - exoplanets. Studying exoplanets is exciting because it provides context for the evolution of Solar System planets, but also involves several challenges.Only rarely can we directly observe an exoplanet, because stars are so much larger and brighter. Instead, we measure the dip in the amount of light coming from the parent star when the planet passes in front. Gases and cloud particles absorb and scatter particular colours - or wavelengths - of light, so by measuring precisely the amount of light blocked by the planet at each wavelength, we can identify the unique fingerprints of substances in the planet's atmosphere - all without seeing the planet!However, there's a catch: we only get a single measurement averaged over the whole of the planet's visible atmosphere, which is not uniform and changes with time. To truly compare exoplanets with Solar System worlds, we need to understand what this average measurement actually represents. I aim to investigate, using computational models of light passing through an atmosphere, how a 3D, time-varying, cloudy exoplanet atmosphere can best be studied using these measurements. I will compare models with data from the new James Webb Space Telescope, due to be launched in 2021, which is set to provide the most detailed and precise observations of exoplanets yet.