Which of the following pairs is not correctly matched? Month Position of Sun

1. Earth's Axial Tilt and Orbital Plane (basic)

To understand how time and seasons work, we must first look at how Earth sits in space. Imagine the Earth traveling around the Sun on a flat, invisible sheet; this flat surface is called the Orbital Plane or the Ecliptic Plane. If Earth were perfectly "upright," its axis (the imaginary line it spins on) would be exactly 90° to this plane. However, Earth is tilted.

There are two key ways to measure this tilt, and it is vital not to confuse them. First, Earth's rotational axis is tilted 23.5° away from the "normal" (a vertical line perpendicular to the orbital plane). Because of this, the axis makes an angle of 66.5° with the orbital plane itself (90° - 23.5° = 66.5°). Physical Geography by PMF IAS, The Motions of The Earth and Their Effects, p.251. This fixed tilt is the fundamental reason why different parts of the Earth receive varying amounts of sunlight throughout the year.

It is also important for UPSC aspirants to distinguish the Geographic Axis from the Magnetic Axis. While the geographic axis is what determines our seasons and rotation, the Earth's magnetic field is actually tilted at a different angle—approximately 11° relative to the rotational axis. Physical Geography by PMF IAS, Earths Magnetic Field (Geomagnetic Field), p.72. In geography and time-keeping, we primarily focus on the 23.5° geographic tilt.

Sources: Physical Geography by PMF IAS, The Motions of The Earth and Their Effects, p.251; Physical Geography by PMF IAS, Earths Magnetic Field (Geomagnetic Field), p.72

2. Rotation vs. Revolution: The Periodic Cycle (basic)

To understand the Earth's rhythm, we must distinguish between its two primary movements: Rotation and Revolution. Think of the Earth like a spinning top that is also racing around a giant track. The Rotation is the Earth spinning on its own imaginary line called the axis, which connects the North and South Poles. This daily spin takes approximately 24 hours and is the reason we experience the cycle of day and night Physical Geography by PMF IAS, The Motions of The Earth and Their Effects, p.267. Beyond just light and dark, this rotation creates the Coriolis force, which deflects winds and ocean currents, and contributes to the daily rise and fall of tides Physical Geography by PMF IAS, The Motions of The Earth and Their Effects, p.268.

While spinning, the Earth also travels in a massive loop around the Sun; this is Revolution. It takes about 365¼ days to complete one full orbit. We usually simplify a year to 365 days, but those extra six hours aren't ignored—they are bundled together every four years to create a Leap Year of 366 days, where February gets an extra day Physical Geography by PMF IAS, The Motions of The Earth and Their Effects, p.252. The path the Earth takes is not a perfect circle but an ellipse (an oval shape). The flat surface on which this orbit happens is known as the orbital plane or the ecliptic.

Because the orbit is elliptical, the Earth's distance from the Sun changes throughout the year. When the Earth is at its closest point to the Sun (about 147 million km), we call it Perihelion, which usually occurs around January 3rd. Conversely, when it is farthest away (about 152 million km), it is at Aphelion, occurring around July 4th Physical Geography by PMF IAS, Ocean Movements Ocean Currents And Tides, p.506. Interestingly, these distances affect the intensity of tides, with greater tidal ranges occurring during Perihelion Physical Geography by PMF IAS, The Motions of The Earth and Their Effects, p.255.

Sources: Physical Geography by PMF IAS, The Motions of The Earth and Their Effects, p.252, 255, 267, 268; Physical Geography by PMF IAS, Ocean Movements Ocean Currents And Tides, p.506

3. Defining Important Latitudes (basic)

When we look at a globe, the lines of latitude seem like simple markers, but they are actually profound indicators of how our planet interacts with the Sun. Because the Earth is tilted on its axis by about 23.5°, the Sun’s direct rays don't always hit the same spot. This tilt defines four critical parallels beyond the Equator (0°) and the Poles (90°) that every UPSC aspirant must memorize.

The first set of markers are the Tropics. The Tropic of Cancer (23½° N) and the Tropic of Capricorn (23½° S) represent the absolute northernmost and southernmost limits where the midday Sun can ever be seen directly overhead Physical Geography by PMF IAS, Latitudes and Longitudes, p.240. The region between these two lines is known as the Torrid Zone. In this zone, the Sun hits the Earth at a very direct angle at least twice a year (and once at the Tropics themselves), making it the hottest part of the planet Physical Geography by PMF IAS, Latitudes and Longitudes, p.242.

Moving further toward the poles, we encounter the Arctic Circle (66½° N) and the Antarctic Circle (66½° S). These lines are special because they mark the boundaries of 24-hour day and night. Beyond these circles, there are periods in the year when the sun never sets in summer (the "Midnight Sun") and never rises in winter Certificate Physical and Human Geography, GC Leong, The Arctic or Polar Climate, p.233. The areas between the Tropics and these Circles are the Temperate Zones, where the sun is never directly overhead, leading to moderate temperatures.

Sources: Physical Geography by PMF IAS, Latitudes and Longitudes, p.240; Physical Geography by PMF IAS, Latitudes and Longitudes, p.242; Certificate Physical and Human Geography, GC Leong, The Arctic or Polar Climate, p.233

4. Latitudinal Heat Zones of the Earth (intermediate)

To understand why different parts of the Earth have vastly different climates, we must look at how the Earth receives solar energy. Because the Earth is a sphere and its axis is tilted at an angle of 66½° to its orbital plane, the angle of the sun’s rays varies significantly as we move from the Equator toward the poles. This variation creates distinct Latitudinal Heat Zones.

The intensity of heat depends primarily on the angle of incidence. When the sun is directly overhead, its rays are vertical. These vertical rays are concentrated over a small surface area and travel a shorter distance through the atmosphere, losing less energy to scattering or absorption. Conversely, as the latitude increases, the rays become more slant. These slant rays spread the same amount of solar energy over a much larger area and must pass through a thicker layer of the atmosphere, which significantly reduces the net energy reaching the surface FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.), Solar Radiation, Heat Balance and Temperature, p.68.

Based on this heat distribution, the Earth is divided into three primary zones:

It is a common misconception that the sun can be overhead anywhere on Earth. In reality, the limit of the overhead sun is strictly defined by the Tropics. During the Equinoxes (March and September), the sun is overhead at the Equator; during the June Solstice, it reaches the Tropic of Cancer; and during the December Solstice, it reaches the Tropic of Capricorn. Beyond these boundaries, the sun always appears at an angle, never directly at the zenith.

Sources: FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.), Solar Radiation, Heat Balance and Temperature, p.68; Exploring Society: India and Beyond, Social Science-Class VI, NCERT (Revised ed 2025), Locating Places on the Earth, p.14; Physical Geography by PMF IAS, Manjunath Thamminidi, Chapter 18: Latitudes and Longitudes, p.242

5. The Circle of Illumination and Polar Day/Night (intermediate)

To understand why some parts of our planet experience months of sunlight while others remain in darkness, we must first visualize the Circle of Illumination. Imagine the Earth as a giant sphere in space; because the Sun is our only major light source, it can only ever light up exactly one-half of the globe at any given moment. The imaginary line that separates the lighted half (day) from the dark half (night) is what we call the Circle of Illumination. This line is a Great Circle, much like the Equator, because it divides the sphere into two equal halves Certificate Physical and Human Geography, Chapter 2, p.14.

If the Earth’s axis were perfectly vertical, this circle would always pass through the North and South Poles, giving every place on Earth exactly 12 hours of day and 12 hours of night. However, because the Earth is tilted at 23.5°, the Circle of Illumination rarely passes through the poles. Instead, it "swings" back and forth throughout the year. On the Equinoxes (March 21 and September 23), the circle does pass through the poles, resulting in equal day and night worldwide Science-Class VII, Earth, Moon, and the Sun, p.179. But as the Earth moves toward the solstices, one pole begins to lean into the light while the other retreats into the shadow.

This tilt creates the phenomenon of Polar Day and Polar Night. During the Summer Solstice (around June 21), the Northern Hemisphere is tilted toward the Sun. The Circle of Illumination shifts beyond the North Pole to reach the Arctic Circle (66.5°N). Consequently, the entire region from the Arctic Circle to the North Pole remains in the lighted half even as the Earth rotates. This is the famous Midnight Sun, where the sun stays visible for 24 hours at the Arctic Circle and for up to six continuous months at the North Pole Physical Geography by PMF IAS, Chapter 19, p.253. Conversely, the South Pole is hidden in the dark half, experiencing a six-month night.

It is crucial to remember that while the sun may be visible for 24 hours at the Arctic Circle, it is never directly overhead there. The vertical or midday sun only ever migrates between the Tropic of Cancer and the Tropic of Capricorn. Beyond these tropics, the sun always appears at an angle, hanging low near the horizon even during the peak of the polar summer.

Sources: Certificate Physical and Human Geography, The Earth's Crust, p.14; Science-Class VII, Earth, Moon, and the Sun, p.179; Physical Geography by PMF IAS, The Motions of The Earth and Their Effects, p.253

6. The Apparent Movement of the Sun: Solstices and Equinoxes (exam-level)

To understand why seasons change and why day lengths vary, we must look at the apparent movement of the Sun. This phenomenon is not caused by the Sun moving up and down, but by the Earth's axial tilt of 23.5° combined with its revolution around the Sun. This tilt ensures that the direct, vertical rays of the midday Sun appear to "migrate" throughout the year. However, this migration is strictly confined to the Torrid Zone—the region between the Tropic of Cancer (23.5°N) and the Tropic of Capricorn (23.5°S). The Sun never shines vertically overhead at any latitude beyond these limits, such as the Arctic Circle or the temperate zones Certificate Physical and Human Geography, Chapter 2, p.7.

Twice a year, we experience the Solstices, which mark the Sun's northernmost and southernmost limits. On the June Solstice (around June 21st), the Northern Hemisphere is tilted toward the Sun, and the midday rays fall vertically on the Tropic of Cancer. This is the longest day of the year for the Northern Hemisphere Physical Geography by PMF IAS, Chapter 19, p.252. Conversely, on the December Solstice (around December 22nd), the Sun is directly overhead at the Tropic of Capricorn, bringing summer to the Southern Hemisphere and the shortest day of the year to the Northern Hemisphere Science-Class VII . NCERT(Revised ed 2025), Earth, Moon, and the Sun, p.179.

Between these extremes are the Equinoxes (meaning "equal nights"), occurring around March 21st and September 23rd. During an equinox, neither pole is tilted toward the Sun; the Earth’s axis is at right angles to the Sun's rays. Consequently, the midday Sun is vertically overhead at the Equator. On these two days, almost every place on Earth experiences exactly 12 hours of daylight and 12 hours of darkness Physical Geography by PMF IAS, Chapter 19, p.254.

Comparison of Solar Positions

Sources: Certificate Physical and Human Geography, GC Leong, Chapter 2: The Earth's Crust, p.7; Physical Geography by PMF IAS, Chapter 19: The Motions of The Earth and Their Effects, p.252; Physical Geography by PMF IAS, Chapter 19: The Motions of The Earth and Their Effects, p.254; Science-Class VII . NCERT(Revised ed 2025), Earth, Moon, and the Sun, p.179

7. Solving the Original PYQ (exam-level)

This question brings together your understanding of the Earth's axial tilt and its annual revolution. You have learned that because the Earth is tilted at 23.5°, the midday sun's vertical rays migrate in a cycle throughout the year. The most critical building block here is the concept of the Torrid Zone; as explained in Physical Geography by PMF IAS, the sun can only ever be vertically overhead between the Tropic of Cancer (23.5°N) and the Tropic of Capricorn (23.5°S). If you remember this geographical limit, you can immediately identify that any latitude beyond these tropics—such as the Arctic Circle—is a physical impossibility for a 90-degree solar angle.

To arrive at the correct answer, simply walk through the solar calendar. In June, the Northern Hemisphere tilts most toward the sun, placing it over the Tropic of Cancer. By December, the tilt favors the Southern Hemisphere, placing it over the Tropic of Capricorn. The Equinoxes in March and September represent the "balance points" where the sun is directly over the Equator. Therefore, Option (D) is the correct answer because it is not correctly matched; the sun is overhead at the Equator in September, not the Arctic Circle. As Certificate Physical and Human Geography by GC Leong emphasizes, the altitude of the midday sun decreases as we move poleward, meaning it can never reach the zenith at the Arctic Circle.

UPSC often uses Option (D) as a trap to exploit confusion between "daylight duration" and "solar zenith." Students often remember that the Arctic Circle experiences 24 hours of daylight during the summer, but they mistakenly equate constant light with overhead sun. Options (A), (B), and (C) are the three "pivotal" correct matches that define our seasons. Always remember: the sun's overhead path is strictly confined to the tropics; it never ventures into the temperate or frigid zones, making any option involving the Arctic Circle an immediate red flag.