# Images of planet Mars and related input

It was by studying the orbit of planet Mars and the obesrvational data collected by Tycho Brahe that
Johannes Kepler was able to formulate his laws of planetary motion in the early 1600s ,
concluding that the orbits of the planets are ellipses, with the Sun at one focus of the ellipse.
The Martian atmosphere is very thin , composed mainly of carbon dioxide (between 95% and
96%) ,and  contains nitrogen , oxygen ,argon and traces of water vapor.
Mars appears to have a red or red-orange color.Its surface , rocks and soil contain dust composed
mainly of iron which reacted with oxygen , giving iron oxide or rust.This red colored dust has been
carried by storms into the atmosphere and has covered most of the Martian surface and  landscape.

The following images of Mars were made with Redshift and Starry Night.

We begin with an image of Mars from a position behind the moon Deimos.The date for the image is February 2015.

Phobos and Deimos were discovered in 1877 by Asaph Hall.Both have irregular shapes.Phobos (with a diameter of 22.2 km across or 13.8 miles) is larger than Deimos (with a diameter of 12.6 km or 7.8 miles) and is closest to Mars.

Next is an image of Mars showing also Phobos , Deimos and some planets of the solar system.

The third image features Phobos and Mars with Planum Boreum , the North polar cap of Mars , consisting mostly of water ice.

Below is a detailed image of Planum Boreum and its surroundings , including Vastitas Borealis , the largest lowland region of Mars.

Click here to view an enlarged and more detailed image of Planum Boreum.

Here is a simple way to find the surface gravity g for Mars.The same equation used to determine
the value of g on Earth’s surface can also be used to determine the acceleration of gravity or
surface gravity on the surface of other planets.
We equate the force of gravity at the surface of a planet,or the force on an object in a gravitational
field F=mg (also called weight) with the force of gravity between objects in space given by the
Universal Law of gravitation $F =\frac {G M m} {r^2}$ .
Hence:

The value of g obtained here may be very slightly different from values cited in textbooks because
we used specific  and more detailed or accurate values of the constants.
The ratio of the surface gravity of Mars compared to Earth is 3.72761/9.80665 or 0.38011,which
means the surface gravity of Mars is about 38% that of Earth.

Mars is close to Earth and the fourth planet from the Sun , and it has become famous in the past
decades or years  because people and humans have been planning and wanting to go and set foot on the
red planet , some people intending to go there in an unprepared  and unrealistic way.
I think it must be taken into account that a manned mission to Mars and the first mission/trip ( or even trips) to
Mars should be undertaken as part of an international enterprise with international cooperation and an international crew , consisting of people very well prepared ,well trained ,well versed in science ,engineering , technology , astronautics and aviation (preferably having pilot skills) , and having planned everything to the tiniest detail in order
for the crew to go land on Mars , stay there for a short determined period of time , conduct
experiments , establish a base for future trips , and come back to Earth safely.
Not to offend anyone ,but this is not a game or a one-way voyage with uncertain or harmful results and consequences.This will be a very important event in the history of humankind , and not everyone is ready,
prepared or able to make the journey to Mars .