WIDEMANN , Thomas

Measuring the atmospheric circulation of Venus at different altitudes is important for understanding its complex dynamics, in particular the mechanisms driving super-rotation. Observationally, Doppler imaging spectroscopy is in principle the most reliable way to measure wind speeds of planetary atmospheres because it directly provides the...

Solar light gets scattered at cloud top level in Venus' atmosphere, in the visible range, which corresponds to the altitude of 67 km. We present Doppler velocity measurements performed with the high resolution spectrometer MTR of the Solar telescope THEMIS (Teide Observatory, Canary Island) on the sodium D2 solar line (5890A˚). Observations...

We exploit the solar transits of Venus in 2004 and 2012, to derive useful constraints on the mesosphere of the planet by the observation of the so-called "aureole" resulting from direct sunlight refraction. In 2012 we organized an extensive campaign, involving observations through both space- and ground- based telescopes. A specific design...

On 5-6 June 2012, Venus will be transiting the Sun for the last time in this century. This unique opportunity, besides offering the opportunity of investigating the mesosphere of the planet, also provides a significant nearby analog of exoplanet transits. Several studies using the transmission spectroscopy technique have provided significant...

During the Venus transit in 2004 several observers collected data useful to the characterization of the mesosphere of the planet, by observing the solar light refracted at the corresponding altitude range. The "aureole" thus formed, is observable during the ingress and egress phases of the transit, when Venus is crossing the solar limb. For the...