Mars is often considered Earth’s twin, sharing many similar qualities such as its long Martian days referred to as sols.
Mars shares Earth’s axial tilt and spin period, giving rise to similar seasons like spring, summer, autumn and winter. However, its orbital eccentricity is larger.
Daytime
Mars is often referred to as Earth’s “Twin.” It shares many characteristics with Earth, such as polar ice caps and seasons; yet there are distinct distinctions that set Mars apart compared with our home planet – one being its day length; Mars takes longer to rotate on its axis than does Earth. An average Martian day lasts 24 hours and 37 minutes!
Mars lies closer to the Sun than Earth, which drastically alters its climate. Temperatures on both air and ground surfaces vary considerably between very cold polar regions and hotter equatorial zones, as does sunlight hitting surface area based on season; maximum sunlight occurs around noon every day on Mars.
Mars boasts two natural satellites, or moons. Both moons are small and irregularly-shaped, suggesting they were captured asteroids. Phobos is close to Mars while Deimos lies farther away; both moons possess relatively minor masses so their gravitational pull on Mars is minimal.
Martian months differ significantly from Earth in that there is no moon to mark time as we know it; instead, scientists use the time of year when the Sun passes closest or farthest away as a marker of sols – this phenomenon is known as solar longitude (Ls). Ls is zero at vernal equinox (beginning of northern spring), 90 at summer solstice, 180 at autumnal equinox and 270deg at winter solstice.
At Mars perihelion, it is summer in the northern hemisphere and winter in the southern. Northern spring/southern autumn lasts 194 sols; winter/southern spring and summer each last 142 sols; while northern fall/southern winter lasts 178 sols. Furthermore, seasonal variations and latitude effects also play a role; at 40deg north latitude sunrise times vary between 04:10 on 9 Mina to 08:01 on Kanya 28, representing an impressive change of 2h 54m!
Nighttime
Mars is the fourth planet from the Sun and half as big as Earth; however, its distance is nearly twice that of our home world. Yet despite these differences, many features on Mars resemble our own in many respects – its day lasts exactly as long, its orbit follows an orbit similar to our own and there are seasonal weather variations and polar ice caps just like here on Earth. Mars contains water, though most of it is frozen. When seen at night, all its major features can be observed by anyone. To do so safely requires at least four-inch telescope with clear skies; for optimal viewing during opposition (December 8), which occurs when Mars and Sun align directly opposite one another – setting in the West while rising in the East respectively and making for the brightest viewing conditions possible.
Mars rotates once every 24 hours and 37 minutes, and this period is known as one Martian day (Ls). A solar day begins where the sun sets at vernal equinox and ends where it rises on summer solstice – which equates to 24 hours 37 minutes on Martian time.
Mars experiences variable length days due to its tilt toward the sun. This causes some areas of its surface to be exposed more intense sunlight than others and thus creating seasons – the winter solstice sees larger polar ice caps while summer solstice brings their receding.
Mars days are almost 40 minutes longer than those on Earth; therefore, inhabitants would need their own way to track time on this distant world. Julian dates may be used to mark special dates while also developing their own calendar that marked solstice, perihelion and aphelion events.
One way of measuring the length of a Martian day is through Doppler-shifted radio signals. This phenomenon creates the same effect as emergency vehicle sirens: rising pitch nearer arrival and lower pitch when departing. Spirit and Opportunity rovers were doppler-shifted when near the equator or tropical circle, giving an accurate reading.
Temperature
Mars follows an Earth-style day-night cycle; each 24-hour day lasts 24 hours, 39 minutes and 35 seconds on Mars and is known as a sol (short for solar day). Furthermore, two natural satellites orbit it three times each sol.
Mars is covered by a thin atmosphere that allows solar heat to escape the planet and has caused its temperatures to vary widely, from nearer the equator being warmest, while poles may experience drastic temperature shifts, leading to their respective polar caps to grow and shrink accordingly.
Mars’ axis is also tilted, creating seasons on its surface; summer heat causes its polar ice caps to melt while freezing temperatures cause them to freeze solid in winter and expand in summertime. Polar caps also change shape throughout their orbital journey by expanding or contracting depending on season and climate change, shifting across space-time in response.
Mars is approximately half the size and farther from the Sun than Earth, which explains why its orbit around our star takes longer. This period, known as a Martian year, takes approximately 687 days or two Earth years before reaching perihelion – its closest approach to Sun.
As Mars progresses through its year, it moves closer to the Sun and experiences more sunshine. By mid-July it has reached its aphelion distance from Sun; these are both major landmarks where solar activity peaks most strongly during each Martian year.
As Mars does not possess a moon to provide months, scientists find it impractical to use a civil calendar as a method of keeping track of events over long periods. Instead, Julian days count provides an easier method of keeping tabs on events spanning decades – the length of each year differs depending on its distance from either its perihelion or aphelion – those close to either end tending to be shorter than years between either extreme.
Atmosphere
An atmosphere is the mixture of gases surrounding any celestial body, such as the Earth or Moon, that surrounds and protects them from radiation and gives them their distinct colors and aroma. Furthermore, an atmosphere can retain heat and moisture for life to survive on planets. Scientists use numerous techniques to study Mars’ atmosphere including radio telescopes, ground radar, spacecraft data analysis, radio telescopes and ground-based radar. Such measurements provide insights into both its structure and history.
Mars’ atmosphere can change drastically from day to day. Temperatures near the equator tend to be warmer while those at higher latitudes experience cooler conditions. Large dust storms often form in summer when strong winds pick up particles from its surface and deposit them around Mars; such storms prevent scientists from accessing any parts of its surface using cameras and instruments.
Mars is often referred to as Earth’s “twin.” The planet shares similar features to our own such as polar ice caps and seasonal changes, and has similar rotation rates as Earth. On average, Martian days last 24 hours 39 minutes and 37 seconds while solar days may extend longer due to faster rotation at farthest distance from Sun.
Scientists need to fully comprehend what’s going on with Mars’ rotation in order to accurately measure its day length, which they do by employing a method known as solar longitude. This measurement takes into account where the Sun was during various times during a year such as vernal equinox or winter solstice; then converted into Mars time called sols.
Due to Mars’ rotation, light travels a different path when reaching its surface than on Earth; therefore, sunrise and sunset times vary slightly between locations on Mars due to tilt of its axis and orbit around Sun.
Mars’ atmosphere is much thinner than that found here on Earth due to millions of years’ of magnetic field erosion, leaving its atmosphere vulnerable to solar wind pressure and stripping away lighter molecules from its atmosphere, eventually leading to it thinning out over time. NASA is studying this phenomenon with their MAVEN mission.