4th planet from the sun
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Mars: The Fourth Planet from the Sun
Introduction to Mars
Mars, often referred to as the "Red Planet," is the fourth planet from the Sun and the outermost of the rocky, terrestrial planets in our solar system. It is known for its distinctive red color, which is due to iron oxide (rust) on its surface. Mars is the second smallest planet in the solar system, with only Mercury being smaller2.
Physical Characteristics of Mars
Size and Gravity
Mars has a surface gravity of 3.71 m/s², which is about 37.6% that of Earth's gravity. This means that objects on Mars weigh significantly less than they do on Earth2.
Atmosphere
The Martian atmosphere is thin, with a pressure of approximately 0.6 kPa, compared to Earth's 101 kPa. It is composed mostly of carbon dioxide (95%), with traces of nitrogen and argon2.
Rotation and Orbit
Mars has a rotational period (sidereal day) of 24 hours and 37 minutes, making its day slightly longer than Earth's. The Martian solar day, or sol, is 24 hours and 40 minutes. Mars' orbit around the Sun is more elliptical than Earth's, with an eccentricity of 0.093, leading to more significant variations in its seasons. The sidereal period of Mars is 687 Earth days, while the synodic period, or the interval between oppositions of Mars, averages 780 days2.
Axial Tilt and Seasons
Mars has an axial tilt of 25 degrees, which is similar to Earth's tilt. This tilt causes Mars to experience seasons, although they are longer due to its longer orbital period. The progress of the seasons on Mars is commonly given by Ls, the orbital longitude measured from the northern hemisphere's spring equinox2.
Mars in the Context of the Solar System
Position and Composition
Mars is the fourth planet from the Sun, following Mercury, Venus, and Earth. It is part of the inner solar system, which consists of the rocky, terrestrial planets. Mars' surface is characterized by its red color, large volcanoes, deep canyons, and evidence of ancient riverbeds2.
Exploration and Study
Mars has been a primary target for exploration due to its potential for past or present life and its similarities to Earth. Numerous missions have been sent to Mars, including orbiters, landers, and rovers, to study its surface, atmosphere, and potential for habitability.
Conclusion
Mars, the fourth planet from the Sun, is a fascinating world with many similarities and differences compared to Earth. Its thin atmosphere, longer days, and significant seasonal changes make it a unique subject of study in our solar system. Understanding Mars helps scientists learn more about the history and evolution of our planetary neighborhood.
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Most relevant research papers on this topic
Images of a fourth planet orbiting HR 8799
The presence of a fourth planet in the HR 8799 system challenges current planet formation models, offering a unique laboratory for studying the formation and evolution of giant planets at wide distances.
Highly CitedA fourth planet orbiting υ Andromedae
The discovery of a fourth planet in Andromedae's system, similar to Jupiter, makes this system the fifth to contain four planets, with strong interactions between them.
The HARPS search for southern extra-solar planets. VIII. μ Arae , a system with four planets
The HARPS spectrograph confirms the presence of a fourth planet in the Arae planetary system, confirming the existence of Arae c, Arae d, and Arae e.
Highly CitedThe HARPS-N Rocky Planet Search. I. HD 219134 b: A transiting rocky planet in a multi-planet system at 6.5 pc from the Sun
HD219134b, the nearest known transiting planet, is a rocky planet in a multi-planet system at 6.5 pc from the Sun, with a mean density of 5.89 g/cc.
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