Mars represents a conundrum for astronomers and scientists. It is both similar and different from our planet in several ways. Mars is cold, dry, has a fragile atmosphere, receives little precipitation, and nothing grows on its surface. At the same time, its internal structure consists of a silicate mantle and crust, and a metallic core just like the Earth. It also holds plenty of water in the form of polar ice caps. The most striking similarity between the two planets is the length of their respective days. A day on Mars is 40 minutes longer than a day on Earth.
Length of a Day
The difference of a day on Mars and Earth is incredibly small compared to other planets in the solar system where a day is either much longer or much shorter short compared to Earth. For example, a day on Jupiter is 9 hours, 53 minutes, and 29.69 seconds which is less than half a day on Earth whereas a day on Venus is 113 days and 18 hours.
Determining the Length of a Day
There are two ways of determining the length of a complete rotation of celestial objects: sidereal and solar. A sidereal day is the length of time it takes a planet to make a full rotation on its axis so that the stars appear in the same position as the previous day. This takes about 23 hours, 26 minutes, and 4.1 seconds on Earth and 24 hours, 37 minutes, and 22 seconds on Mars. In contrast, a solar day is the duration it takes a planet to make a complete rotation so that the sun appears in the same position as the previous day. This duration is 24 hours on Earth and 24 hours, 39 minutes, and 35 seconds on Mars, but it is occasionally rounded up to 24 hours 40 minutes.
Mars has a seasonal cycle just like Earth. This is attributed to the fact that the planet has a 25.19° tilt compared to Earth’s 23.44°. The seasonal cycle is also attributed to the planet’s orbital eccentricity that ranges between 128.4 million miles and 154.8 million miles from the sun. The change in distance results in variations in temperature. Although Mars’ average temperature is 51°F (-46°C), the temperature can drop to as low as -225.4°F during the winter and rise to 95°F during the summer. In 2008, the Phoenix Lander discovered water ice caps in the polar regions of mass, and in 2012, the Mars Reconnaissance Orbiter found that carbon-dioxide snowfalls were frequent in Mars' South Pole. Large and wild dust storms are frequent and can last for several days.