عنوان مقاله [English]
It was previously thought that the probability of existence of life on Mars is more than other places in the space. Although Mars is half the size of Earth, it is similar to our planet in other aspects. Days in Mars are half an hour longer than our days, and it has a cloudy atmosphere. There are ice caps there that melt during summer and expand over winter. There are also plains in there. Most interesting of all are the signs that change every year in terms of size and shape and look almost like plants that are growing. Some of astronomers have even thought that they could see canals dug by Mars residents to transfer water from poles to plains.
Space explorations have revealed many facts on Mars, but no sign of life has been discovered there. First, it is very cold there; even in a summer day the temperature will not rise above the freezing point of water. Second, the thickness of air layer on this planet is similar to thickness of air layer at an elevation of about 35 kilometers (22 miles) from Earth’s surface, so it is not possible to breathe in there. Ultraviolet radiations of the Sun reaching the surface of Mars are so strong that they would destroy every living being.
There is water on Mars’s surface, but it is not in liquid form. This water lies in frozen state under the surface and within ice caps. However, water has probably existed in liquid form in the past. Some of the signs over the planet look like dried-up rivers. Maybe Mars have been warmer in the past, so that water could have been melted.
River beds are not like canals on Mars. They are apparently illusions that deceived astronomers when looking through their telescopes. The dark points that once were supposed to be plants are in fact areas of dark rocks and dust. They change every year in terms of size, because dusts are dispersed by winds.