Atmosphere of Mars slowly decreased to very low concentrations, with no layer detectable above 35 km. The reporting scientists think that the observed polar ozone layers are the result of the same atmospheric circulation pattern that creates a distinct oxygen emission identified in the polar night and also present in Earth's atmosphere. This circulation takes the form of a huge Hadley cell in which warmer air rises and travels toward the south pole before cooling and sinking at higher latitudes. Mars is on a quite elliptical orbit and has a large axial tilt, which causes extreme seasonal variations in temperature amongst the northern
Atmosphere of Mercury pushes neutral atoms away from Mercury, creating a comet-like tail behind it. The main component in the tail is sodium, which has been detected beyond 24 million km (1000 R) from the planet. This sodium tail expands rapidly to a diameter of about 20,000 km at a distance of 17,500 km. In 2009, "MESSENGER" also detected calcium and magnesium in the tail, although these elements were only observed at distances less than 8 R. Atmosphere of Mercury Mercury has a very tenuous and highly variable atmosphere (surface-bound exosphere) containing hydrogen, helium, oxygen, sodium, calcium, potassium and water vapor, with a