Fourth planet from the sun
Pro Research Analysisby 
Searched over 200M research papers
Mars: The Fourth Planet from the Sun
Introduction to Mars
Mars, the fourth planet from the Sun, is a fascinating world that has captivated human curiosity for centuries. Known as the "Red Planet" due to its reddish appearance, Mars is the outermost of the rocky, terrestrial planets in our solar system6. It is the second smallest planet, with only Mercury being smaller6.
Physical Characteristics of Mars
Mars has a surface gravity of 3.71 m/s², which is about 37.6% that of Earth6. The planet's atmosphere is thin, with a pressure of approximately 0.6 kPa, and is composed mostly of carbon dioxide (95%)6. Mars has an obliquity (tilt of the axis) of 25 degrees, which has varied significantly over millions of years6. The rotational period of Mars is slightly longer than Earth's, with a sidereal day lasting 24 hours and 37 minutes6. The Martian year, or sidereal period, is 687 Earth days, while the synodic period relative to Earth averages 780 days6.
Mars' Orbit and Seasons
Mars has a more elliptical orbit compared to Earth, with an eccentricity of 0.0936. This results in varying lengths of seasons, with northern spring being the longest6. The progress of the seasons on Mars is often measured by the orbital longitude (Ls), with Ls = 90 marking the summer solstice in the northern hemisphere and the winter solstice in the southern hemisphere6.
Mars Exploration and Research
Mars has been the subject of extensive exploration and research. Various missions and instruments have significantly advanced our understanding of the Martian environment, geography, and geology8. These missions aim to provide a broad overview of Mars, rather than an exhaustive summary of every aspect of the planet's evolution8.
Conclusion
Mars, the fourth planet from the Sun, continues to be a focal point of scientific research and exploration. Its unique characteristics, such as its thin atmosphere, varying obliquity, and elliptical orbit, make it a compelling subject for study. As we continue to explore Mars, we gain valuable insights into the history and evolution of our solar system.
Sources and full results
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 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.
Highly CitedThe 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 Cited