Abstract

By measuring transiting planets, we can now “see” the atmospheres of hot gas giants, and measure spectroscopic features from the UV to the near infrared. The atmosphere of these planets are quite different from anything in the solar system, with supersonic winds, rock and iron rains, and titanium oxide sunblock to name but a few exotic features.

A large observational effort has been invested in measuring molecules in these atmospheres with the Spitzer satellite. Our group has concentrated on transmission spectroscopy in the visible, which is more sensitive to the physical conditions in the atmosphere, and the presence of dust, haze and clouds.

The main result – “as usual”, one is tempted to say – is that the spectra sketched by the observations bear little resemblance with model expectations. In this talk I will evoke the results of our Hubble and ground-based observations, propose some possible interpretation, and sketch the coming observations, including our on-going 200-orbit programme with the Hubble Space Telescope.