The He I and He II chromospheric shells and the Transition Region

Total eclipse observations were performed in 2008 and 2009 to study the He I and He II shells near the 1 Mm heights above the solar limb. They suggest that the corona penetrates deep into the chromosphere following magnetic chanels. Thanks to the use of a fast CCD camera, the observation of a second ionized helium shell is evidenced for the first time. The transition region is then seen at very low altitude where spicules are emerging. Spicule feet are also discussed, using the best resolution SOT/Hinode HCaII images processed with the non linear operator Madmax to look at details of this ubiquitous part of the solar atmosphere.