Interesting;
(I am translating some pure numbers into literaturehttp://nssdc.gsfc.nasa.gov/planetary/factsheet/)
Mars winter and summer would have a wider variation due to Sun’s relative distance being a 17%; variation in radiation is 34% (2 x 17%)
For earth since distance of earth and sun varies from maximum to minimum within 3.4% the variation in sun’s radiation energy is 2×3.4 = 6.8%
Also Venus is far more closer to Earth in most of its actual parameters. (eg inclinations don’t matter, mass and gravity and pressure etc do) But Venus is 31 times hotter than earth on an average and a person would feel 100 times more pressure from the atmosphere above his head. He would burn and crack like a f** fish.
But look at Mars. Its not as similar to us as Venus. Most parameters are markedly different. 5 times as cold. Pressure is almost 1% of earth and gravity is 62% less. So we would fly off and hit ice bergs. (just for imagination) And as mentioned above there is a 34% variation in energy from sun during winter and summer compared to 7% on earth. Everything is off by significantly large differences. (only day size is ~24 hrs and year is about 2 earth-years, but the surface conditions are not optimal compared to earth)
No other planet except earth has all the right qualities in earth-standards.
Life might not have survived on mars due to large variations in solar radiation from winter to summer. (that difference for Venus is fine compared to earth, almost everything about Venus is close to earth except its temperature and pressure)
Also see that 34.2% is 5.03 times 6.8% and average temperatures are down by that factor (-65+15)/15 = 5.33 !
M Dash Foundation: C Cube Learning 