Sunsets and sunrises on mars are blue due to a large number of dust particles in the atmosphere. Blue light penetrates this type of atmosphere more effectively compared to the longer wavelengths of yellow and red light. For the same reason, during the day the sky appears orange due to the scattering of yellow and red light. ¹⁾

The fourth planet of the solar system is named after the Roman god of war, Mars, because of its red hue visible even with the naked eye. ²⁾

Mars has two small moons, Phobos (22.2 km, 13.8 mi) and Deimos (12.6 km, 7.8 mi). ³⁾

Olympus Mons is the tallest volcano on Mars, and the highest known mountain in the solar system, with a height of 16 miles (25 km). ⁴⁾

The length of the year on Earth is 365.25 days. The year on Mars is almost twice as long! It lasts for 687 Earth days. ⁵⁾

As of December 2020, there are eight missions from around the world actively orbiting Mars or exploring its surface. The missions are from the U.S., European Union, Russia, and India.⁶⁾

On Jan 12, 2021, NASA's Curiosity rover passed 3,000 Martian days of work on the surface of Mars. It managed to travel over 23km (as of Jul 2020). It's powered by a nuclear battery and a radioisotope thermoelectric generator (RTG), which produces energy from the decay of 11 lb (4.8 kg) of plutonium-238 dioxide. ⁷⁾

Opportunity was a robotic rover that was exploring the surface of Mars surface for 15 years between 2004 and 2018. Its mission was planned for 90 sols (Martian days), but it managed to work 5,352 sols (5,498 Earth days). Opportunity drove 45.16 km, took over 224,000 photographs, and made many important findings, including evidence of salty water deep enough to alter rocks. ⁸⁾

According to the study, in about 50 million years, Phobos will come so close to the surface of Mars that it will either fall to its surface or be torn apart by the planet's tidal forces. ⁹⁾

Gravity on Mars is 62.5% of Earth's gravity. ¹⁰⁾

The atmosphere of Mars is more than 100 times thinner than Earth's. It consists of 95.32% carbon dioxide, 2.7% nitrogen, 1.6% argon, 0.13% oxygen, and 0.08% carbon monoxide. In addition, the Martian atmosphere consists of water, nitrogen oxide, neon, krypton, and xenon. ¹¹⁾

According to the study, the surface of Mars is composed mainly of tholeiites and basalt.¹²⁾

The Martian nucleus is composed mainly of iron and about 14-17% sulfur. The Martian nucleus is partially liquid. ¹³⁾

The Noachian Period is the oldest in the geologic history of Mars. ¹⁴⁾

During the Hesperian period, when the Great Bombardment was underway, an ocean may have existed on Mars. ¹⁵⁾

During the Amazonian period, which is the youngest in Mars' geologic history, volcanic activity decreased tenfold compared to the Hesperian period. ¹⁶⁾

Mars has 2 permanent polar ice caps. ¹⁷⁾