Mars

Mars is smaller than Earth and Venus. It possesses an atmosphere of mostly carbon dioxide with a surface pressure of 6.1 millibars (roughly 0.6percent that of the Earth’s). Its surface, peppered whit vast volcanoes such as Olympus Mons and rift valleys such as Valles Marineris, shows geological activity that may have persisted until as recently as 2 milion years ago. Its red colour comes from iron oxide (rust) in its soil. Mars has two tiny natural satellites (Deimos and Phobos) thought to be captured asteroids.
The planet probably got this name due to its red color, Mars is sometimes referred to as the Red Planet. The name of the month March derives from Mars. Mars has been known since prehistoric times.
Though Mars is much smaller than Earth, its surface area is about the same as the land surface area of Earth.
Mars crust is about 80 km. thick in the southern hemisphere but only about 35 km. thick in the north. Mars relatively low density compared to the other terrestrial planets
indicates that its core probably contains a relatively large fraction of sulfur in addition to iron.
Scientists have long speculated about the possibility of life on Mars owing to the planet’s proximity and similarity to Earth. Although fictional Martians have been a recurring feature of popular entertainment, it remains an open question whether life currently exists on Mars, or has existed there in the past. The first spacecraft to visit Mars was Mariner 4 in 1965.
Is there life on Mars?
… maybe!

Bianca Manta,Alexandra Moldovan,Alina Bosa, cls. a VII-a A




Mars


Mars is the fourth planet from the Sun in the Solar System. The planet is named after Mars, the Roman god of war. It is also referred to as the "Red Planet" because of its reddish appearance, due to iron oxide prevalent on its surface. Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the volcanoes, valleys, deserts and polar ice caps of Earth. Unlike the Earth, Mars is now a geologically inactive planet with no known tectonic activity. It is the site of Olympus Mons, the highest known mountain in the Solar System, and of Valles Marineris, the largest canyon. The smooth Borealis basin in the northern hemisphere may be a giant impact feature covering 40% of the planet. Mars’ rotational period and seasonal cycles are likewise similar to those of Earth.
Mars has two moons, Phobos and Deimos, which are small and irregularly shaped. These may be captured asteroids, similar to 5261 Eureka, a MartianTrojan asteroid. Mars can be seen from Earth with the naked eye.

Mars is currently host to three functional orbiting spacecraft: Mars Odyssey, Mars Express, and the Mars Reconnaissance Orbiter. On the surface are the two Mars Exploration Rovers (Spirit and Opportunity) and several inert landers and rovers, both successful and unsuccessful. The Phoenix lander completed its mission on the surface in 2008. Observations by NASA's now-defunct Mars Global Surveyor show evidence that parts of the southern polar ice cap have been receding.
~Soil
In June 2008, scientists compared the soil near Mars's north pole to that of backyard gardens on Earth, and concluded that it could be suitable for growth of plants such as asparagus. In August 2008, the Phoenix Lander conducted simple chemistry experiments, mixing water from Earth with Martian soil in an attempt to test its pH, and discovered traces of the salt perchlorate, while also confirming many scientists' theories that the Martian surface is considerably basic. The presence of the perchlorate, if confirmed, would make Martian soil more exotic than previously believed.
~Geography
Today, features on Mars are named from a number of sources. Large albedo features retain many of the older names, but are often updated to reflect new knowledge of the nature of the features. For example, Nix Olympica (the snows of Olympus) has become Olympus Mons (Mount Olympus). The surface of Mars as seen from Earth is divided into two kinds of areas, with differing albedo. Mars’ equator is defined by its rotation, but the location of its Prime Meridian was specified, as was Earth's (at Greenwich), by choice of an arbitrary point. Since Mars has no oceans and hence no 'sea level', a zero-elevation surface or mean gravity surface also had to be selected. Zero altitude is defined by the height at which there is 610.5 Pa of atmospheric pressure. This pressure corresponds to the triple point of water, and is about 0.6% of the sea level surface pressure on Earth.
~Climate
Of all the planets in the Solar System, Mars's seasons are the most Earth-like, due to the similar tilts of the two planets' rotational axes. However, the lengths of the Martian seasons are about twice those of Earth's, as Mars’ greater distance from the Sun leads to the Martian year being about two Earth years long. Martian surface temperatures vary from lows of about −140 °C (−220 °F) during the polar winters to highs of up to 20 °C (68 °F) in summers. The wide range in temperatures is due to the thin atmosphere which cannot store much solar heat, the low atmospheric pressure, and the low thermal inertia of Martian soil. The planet is also 1.52 times as far from the sun as Earth, resulting in just 43 percent of the amount of sunlight.
~Life
The current understanding of planetary habitability—the ability of a world to develop and sustain life—favors planets that have liquid water on their surface. During perihelion Mars dips inside this region, but the planet's thin (low-pressure) atmosphere prevents liquid water from existing over large regions for extended periods. The past flow of liquid water, however, demonstrates the planet's potential for habitability. Recent evidence has suggested that any water on the Martian surface would have been too salty and acidic to support terrestrial life. The lack of a magnetosphere and extremely thin atmosphere of Mars are a greater challenge: the planet has little heat transfer across its surface, poor insulation against bombardment and the solar wind, and insufficient atmospheric pressure to retain water in a liquid form . Mars is also nearly, or perhaps totally, geologically dead; the end of volcanic activity has stopped the recycling of chemicals and minerals between the surface and interior of the planet. Evidence suggests that the planet was once significantly more habitable than it is today, but whether living organisms ever existed there is still unclear.
Andreea Nacu,Roxana Lepadatu,Roxana Naznean,Cristiana Salagean,cls a VII-a A