MARS

Mars, the "Red Planet", is named after the Roman god of war because it commonly appears with a reddish tinge when viewed in our sky

Mars was the Roman war god; his shield and spear form the planet’s symbol.

We still call the third month of the year, March, in his honor

The month was so named because Mars, the patron god of the Romans, was a war-god, and spring campaigns usually began about that time.

The word martial, pertaining to war, came from Mars, the god of war.

Mars is the fourth planet from the Sun and the seventh largest:

orbit: 227,940,000 km (1.52 AU) from Sun diameter: 6,794 km mass: 6.4219e23 kg

What is the typical temperature on Mars?

The daytime SURFACE temperature is about 80 F during rare summer days, to -200 F at the poles in winter. The AIR temperature, however, rarely gets much above 32 F.

In 2004, the Spirit rover recorded the warmest temperature around +5 C and the coldest is -15 Celsius in the Guisev Crater.

The wide range of temperatures are the cause of extremely high winds across the planet, producing fearsome dust storms which can be seen with telescopes from the Earth. Coupled with seasonal changes at the poles, the surface appearance is constantly changing.

A vast storm, nearly four times the size of Texas, is seen in this 1999 image of Mars. The storm is made up of swirling arms that rotate counterclockwise around a 200-mile-wide eye, very similar to an earthly cyclone. IMAGE: NASA

The wind that formed these dunes was blowing from the bottom left to the top right of the image.

Firstly, there is the steadily increasing atmospheric pressure due to vaporization of the CO2 frost-cap. Higher atmospheric pressure means that more dust can be suspended in the atmosphere for longer periods, and therefore conditions are more suitable for dust storms.

Basically, when the Martian rocky surface is exposed it can become heated by the sun, unlike the polar frost cap which instead vaporizes. Gas above the exposed surface will become heated and convectively rise, resulting in cooler air sweeping down off the polar frost-cap to essentially "replace" the rising warm air. The result is a strong air flow sweeping onto the exposed Martian surface, disturbing surface dust.

Whispy Atmosphere

The martian atmosphere is mainly CO2 (95%), the rest being nitrogen and argon. The very low surface pressure, at around 10 mbar (200 Pa), is due to the lack of depth of atmosphere

95.3% carbon dioxide (CO2),2.7% nitrogen (N2),1.6% argon (Ar),0.15% oxygen (O2),0.03% water vapor (H2O)

The average surface pressure is only about 7 millibars (less than 1% of the Earth's), though it varies greatly with altitude from about 9 millibars in the deepest basins to about 1 millibar at the top of Olympus Mons.

1 psi = 69 millibarsPressure:

Liquid Water on Surface?

Reportedly, liquid water has been discovered running on the surface of Mars in low canyons

Most of its atmosphere was stripped away by the Sun's solar wind. Under these conditions, liquid water cannot exist on the surface. However there is plenty locked up in the polar caps, and probably underground

The Martian atmosphere results in only a weak greenhouse effect that raises the surface temperature by about 5°C. Consequently, most of Mars is well below the freezing point of water for most of the year. Moreover, even when the daytime temperature at low latitudes does climb significantly above freezing, the atmospheric pressure is so low that water ice turns directly into water vapor without first becoming liquid

Phobos and Deimos the Moons of Mars:

It wasn’t until 1877 that the planet Mars was found to have any satellites; but, in that year, the American astronomer Asaph Hall discovered two of them.

Hall named them “Phobos” and “Deimos” so that in the heavens, as in

the myths and in reality, war is accompanied by fear and terror.

Mars's moons are so small that their gravity is not enough to have pulled them into a spherical shape. The first photograph of Phobos was taken by Mariner 9

It is likely that they did not form with the planet, but are captured asteroids. This is believed because they are both small, and Mars is reasonably close to the asteroid belt.

Phobos:Phobos orbits Mars roughly once every 7 hours - much faster than Mars's rotation. From Mars, Phobos is seen to rise then set in only 4 hours.

Due to its great speed, Phobos regularly eclipses the Sun. However, unlike Earth's Moon, Phobos is too small to completely cover the solar disc. Instead it cuts off about a quarter of its light. This happens about 1,300 times a year, each lasting a maximum of 19 seconds!

Phobos is the larger of the two, but would appear from the surface to be about 1/3 of the size of our Moon.

orbit: 9378 km from the center of Mars diameter: 22.2 km (27 x 21.6 x 18.8) mass: 1.08e16 kg

"phobos" is Greek for "fear" (the root of "phobia").

Deimos:

Deimos, on the other hand, is nearly three times further away than Phobos, and orbits Mars in about 30 hours. This is just a little longer than the martian day, so Deimos would hardly move in the night sky

orbit: 23,459 km from Mars diameter: 12.6 km (15 x 12.2 x 11) mass: 1.8e15 kg

In Greek mythology, Deimos is one of the sons of Ares (Mars) and Aphrodite (Venus); "deimos" is Greek for "panic".

Phobos and Deimos may be composed of carbon-rich rock like C-type asteroids. But their densities are so low that they cannot be pure rock. They are more likely composed of a mixture of rock and ice. Both are heavily cratered. New images from Mars Global Surveyor indicate that Phobos is covered with a layer of fine dust about a meter thick, similar to the regolith on the Earth's Moon.

Martian Features:

Tharsis Bulge

This animation was digitized by Calvin J. Hamilton.

Mission: Mars!

http://www-k12.atmos.washington.edu/k12/mars/graphics/Mars_Earth.gif

http://www.nineplanets.org/mars.html

http://csep10.phys.utk.edu/astr161/lect/mars/mars.html

http://www.wordsources.info/mars.html

http://tes.asu.edu/SOLAR_SYST_TOUR/Mars.html

http://dutch.phys.strath.ac.uk/CommPhys2001Exam/David_Speirs/climateandweather.htm