Mars, Nine Planets in Universe
Mars is the fourth planet from the Sun and the second-smallest planet with a thin atmosphere, having the surface features reminiscent both of the impact craters of the Moon, and the valleys, deserts and polar ice caps of Earth. It is the most widely searched planet for life.
Mars has been observed by many different cultures from around the world for hundreds of years. Because of this, it is impossible to credit anyone with its discovery, Mars being easily visible with the naked eye.
Observations dating back to ancient Egyptian astronomers in the 2nd millennium BCE while Chinese records about the motions of Mars appeared before the founding of the Zhou Dynasty in 1045 BCE.
Detailed observations were made even by the Babylonians who developed arithmetic techniques to predict the future position of the planet while the ancient Greeks developed a geocentric model to explain the motions of the planets.
To the ancient Romans, the planet Mars was symbolic of blood and war, the equivalent of the Greek god of war Aries. In the 16th century, Nicolaus Copernicus proposed a heliocentric model for the Solar System in which the planets follow circular orbits around the Sun.
Johannes Kepler revised this creation, yielding an elliptic orbit for Mars that more accurately fitted the observational data. In 1610, Galileo Galilei first observed Mars with a telescope and within a century, astronomers discovered several features of Mars and determined the planet’s rotational period and axial tilt.
It is hypothesized that the Solar System formed from a giant rotating ball of gas and dust known as the pre-solar nebula. Much of it formed the Sun while more of its dust went on and merged to create the first proto-planets. Mars was one of these planets and after the gravity pulled enough swirling gas and dust, it became the fourth planet from the Sun.
Distance, Size, and Mass
Mars is about 227.9 million km / 141.6 million mi or 1.5 AU away from the Sun. It takes sunlight about 13 minutes to reach Mars. The diameter of Mars is 6.779 km or 4.212 mi, slightly more than half the size of Earth.
In a way, its diameter is about the width of the continent of Africa. Mars’s mass is 6.42 x 1023 kilograms, about 10 times less than Earth, and a volume of 1.6318 x 10¹¹ km³ (163 billion cubic kilometers) which is the equivalent of 0.151 Earths. Its entire surface area is similar to that of all the Earth’s continents combined.
Orbit and Rotation
One rotation/day on Mars is completed within 24.6 hours while a whole trip around the Sun or year, is completed within 669.6 days.
Mars has a relatively pronounced orbital eccentricity of about 0.09. Of the seven other planets in the Solar System, only Mercury has a larger orbital eccentricity. It is known that in the past, Mars had a much more circular orbit. At one point, 1.35 million Earth years ago, Mars had an eccentricity of roughly 0.002, much less than that of Earth today.
It is believed that the closest distance between Earth and Mars will continue to mildly decrease for the next 25.000 years.
To know about Earth https://www.knowledgebeach.com/earth-nine-planets-in-universe/