Mars

Mars is the fourth planet in terms of position with respect to the Sun. Its density is lower than that of Earth.

In the cover image you can see the best Earth-based view of Mars ever.  Credit: web “spacetelescope.org”

Characteristics of the planet mars

A body transported to Mars would weigh 1/3 of its weight on Earth, due to the low gravitational force.

Planets
Eight planets of the solar system Credit: Wikipedia

The Martian magnetic field is very weak, about 2 thousandths of Earth’s and with an inverted polarity with respect to Earth.

Mars is rocky in nature, it has a flattening three times that of Earth.

Its equatorial diameter is 6,794 km. and the polar of 6,750 km. The Martian year lasts 687 Earth days.

planets
Planets size Credit: web “universetoday.com”

Current data indicate that its polar axis has an inclination of 25º 11 ‘with respect to the ecliptic orbit. (The obliquity of the terrestrial ecliptic is 23º 27 ’).

Therefore, Mars has seasonal periods similar to those of Earth, although its seasons are longer, given that a Martian year is 687 days, almost twice as long as an Earth year.

Martian surface

On March 4, 2020, the press announced that NASA’s Curiosity robot took a 1.8 billion pixel panorama of Mars.

Mars
Magnificent image of the surface of Mars. Credit: web de la NASA.
solarsystem.nasa.gov/planets/mars/in-depth/

The spots that are observed on its surface are excellent reference points to observe the rotation of this planet.

The Grand Canyon of the Colorado is like a mere scratch, compared to the Marineris Valley on the planet Mars.

As early as 1666, Giovanni Cassini calculated it at 24 hours 40 minutes.

Planets orbit
Seasons in the Martian Year as the Red Planet Orbits the Sun  Credit: web “mars.nasa.gov”

Current, more accurate measurements establish that the solar day on Mars lasts 24 hours 39 minutes 35.3 seconds.

Christian Huygens made the first observations of dark areas on the surface of Mars in 1659, and he was also one of the first to detect the polar caps.

Mars Earth
Approximately every two years, Earth and Mars are at the closest point to each other in their orbits (opposition). Credit: web “phys.org”

The orbit of Mars is very eccentric: between its aphelion and its perihelion, the planet’s distance from the Sun differs by about 42.4 million kilometers.

Thanks to the excellent observations of Tycho Brahe, Kepler came to discover the elliptical nature of planetary orbits previously considered circular.

William Herschel discovered the obliquity of the axis of rotation of Mars.

If the orbit of the Earth is drawn within that of Mars, whose ellipse is much more elongated, it can also be seen that the distance from Earth to Mars is subject to great variations.

Mars opposicion
Mars at Opposition 2012-2025 Credit: web “skymarvels.com”
skymarvels.com/infopages/vids/MarsOpposition.htm

At the time of conjunction, that is, when the Sun is located between the two planets, the distance between Mars and Earth can be 399 million kilometers.

In opposition, that distance is reduced to less than 56 million kilometers and Mars is seen from Earth as the brightest planet after Venus.

Mars distances
Distances between Mars and Earth in the year 2003. Credit: web “esa.int”

Planet Mars may have supported life.

The data sent by the robot Curiosity indicates that in the Yellowknife Bay area, where Curiosity was exploring, there was a river or a small lake that could have harbored the chemical components necessary to create favorable conditions for the life of microbes.

The mission scientists are analyzing the images of the rocks sent by the robot. Their sizes and shapes offer clues to the speed at which the water was flowing across its surface and also to its depth.

As explained by NASA, the keys to this habitable environment come from the data from the analysis of samples carried out by the Chemistry and Mineralogy instruments that Curiosity has.

Mars sunset
Sunset on Mars. Photograph taken from the Spirit robot probe. Credit: NASA/JPL/Texas A&M/Cornell

In the year 2020, NASA send another robot to Mars. The new mission includes the participation of Curiosity and Opportunity, two NASA spacecraft, as well as Stipendi, a European spacecraft currently in orbit of Mars.

The website Google Mars works similar to Google Earth, but refers to the planet Mars: regions, mountains, plains, dunes, canyons, craters, landing zones for the Mars Rovers.

To those who are interested in science fiction, I recommend reading two magnificent books published by Ben Bova, a writer with a good pen and remarkable scientific knowledge: “Mars” and “Return to Mars.”

Both books are read with relish and you learn a lot about what we know about this mysterious planet, so similar to our Earth, and about the difficulties involved in exploring it by human beings. There is intrigue, science and suspense.