The Mars: notes and MCQs for State PSC prelims

The Mars is part of World and Physical Geography. Below are notes on 2 sub-topics, followed by practice MCQs from State PSC and UPSC papers.

Basic Planetary Characteristics (Orbit, Size, Mass, Axial Tilt)

Known as the 'Red Planet' and the 'God of War'.
Fourth planet from the Sun.
Axial Tilt: Approximately 25.19 degrees (similar to Earth's ~23.5 degrees, causing distinct seasons).
Orbital Period: Approximately 687 Earth days.
Size (Diameter): About half the diameter of Earth (~6,779 km).
Mass: Approximately 0.107 times (about 11%) Earth's mass.

Mars is considered the most promising planet in our our solar system (apart from Earth) for past or present life.
Past Habitability: Strong geological evidence suggests abundant liquid water (rivers, lakes, possibly oceans) existed on Mars billions of years ago.
Current Habitability Factors:

The IDL zigs and zags to avoid cutting through countries or island groups, ensuring areas have a consistent date.
When traveling eastward across the IDL (towards the Americas), one subtracts a day (e.g., Sunday becomes Saturday).
When traveling westward across the IDL (towards Asia), one adds a day (e.g., Sunday becomes Monday).
Daylight Saving Time (DST) is the practice of advancing clocks, usually by one hour, during warmer months to make better use of natural daylight.
The Moon rotates on its axis and revolves around the Earth in the same counter-clockwise direction, consistent with the Earth's revolution around the Sun.

Evidence of seasonal, briny liquid water flows (Recurrent Slope Lineae) in some areas.
Subsurface environments offer potential refuge from harsh surface radiation, extreme temperatures, and low atmospheric pressure.
Detection of methane in the Martian atmosphere, which can be a biosignature (though geological origins are also possible).

Extremely thin atmosphere (primarily CO2) offering little protection from solar and cosmic radiation.
Low atmospheric pressure causing liquid water to quickly boil or freeze on the surface.
Very cold average surface temperatures, though some equatorial areas can reach above freezing.
Presence of perchlorates in the soil, which can be toxic to known Earth life forms.

Biosignatures: Scientists search for direct evidence of life (e.g., microfossils) or indirect indicators such as complex organic molecules, specific atmospheric gas compositions (e.g., disequilibrium of gases), and characteristic isotopic fractionation patterns.