In many cases astronomical phenomena viewed from the planet Mars are the same or similar to those seen from Earth but sometimes (as with the view of Earth as an evening/morning star) they can be quite different. For example, because the atmosphere of Mars does not contain an ozone layer, it is also possible to make UV observations from the surface of Mars. Seasons Mars has an axial tilt of 25.19°, quite close to the value of 23.44° for Earth, and thus Mars has seasons of spring, summer, autumn, winter as Earth does. As on Earth, the southern and northern hemispheres have summer and winter at opposing times. However, the orbit of Mars has significantly greater eccentricity than that of Earth. Therefore, the seasons are of unequal length, much more so than on Earth: In practical terms, this means that summers and winters have different lengths and intensities in the northern and southern hemispheres. Winters in the north are warm and short (because Mars is moving fast near its perihelion), while winters in the south are long and cold (Mars is moving slowly near aphelion). Similarly, summers in the north are long and cool, while summers in the south are short and hot. Therefore, extremes of temperature are considerably wider in the southern hemisphere than in the north. The seasonal lag on Mars is no more than a couple of days, due to its lack of large bodies of water and similar factors that would provide a buffering effect. Thus, for temperatures on Mars, "spring" is approximately the mirror image of "summer" and "autumn" is approximately the mirror image of "winter" (if you consider the solstices and equinoxes to be the beginnings of their respective seasons), and if Mars had a circular orbit the maximum and minimum temperatures would occur a couple of days after the summer and winter solstices rather than about one month after as on Earth. The only difference between spring temperatures and summer temperatures is due to the relatively high eccentricity of Mars's orbit: in northern spring Mars is farther from the Sun than during northern summer, and therefore by coincidence spring is slightly cooler than summer and autumn is slightly warmer than winter. However, in the southern hemisphere the opposite is true. The temperature variations between spring and summer are much less than the very sharp variations that occur within a single Martian sol (solar