Geodesy and Celestial Mechanics

Perihelion is the point in Earth's orbit where it is closest to the Sun, occurring around January 3rd each year. Aphelion is the opposite point when Earth is farthest from the Sun.

Meridians are imaginary lines on the Earth's surface that run from the North Pole to the South Pole. They are perpendicular to the equator and are also known as lines of longitude. Latitudes run parallel to the equator (east-west), while meridians run north-south.

When a stone is thrown horizontally (parallel to Earth's surface), it follows projectile motion under gravity. The horizontal component of velocity remains constant (ignoring air resistance), while the vertical component follows accelerated motion due to gravity. The combination of these two perpendicular motions produces a parabolic trajectory.

Nautical mile is a unit of distance equal to 1.852 km, specifically used in maritime and aviation navigation. It is NOT used in astronomy (parsecs and light years are used), not for road distances (km or miles are used), and not specifically for measuring national boundaries.

The Mercator projection is a cylindrical map projection where all meridians (longitude) and parallels (latitude) are represented as straight lines intersecting at right angles. This preserves angles and shapes but distorts size, especially near the poles.

Approximately 71% of Earth's surface is covered by oceans, with the Pacific Ocean alone covering about 46% of water surface and 30% of Earth's total surface. The remaining 29% is land (continents and islands). This percentage is relatively stable over geological time scales.

A light year is a unit of distance used in astronomy to measure vast distances between stars and galaxies. It represents the distance light travels in one year (about 9.46 trillion kilometers or 5.88 trillion miles). This unit is impractical for Earth-bound distances due to its enormous scale.

One light year equals approximately 9.46 trillion km (9.46 × 10^12 km), which is the distance light travels in vacuum in one year at 299,792 km/s. A parsec is about 3.26 light years.

Option (3) is the correct answer. A globe is a 3-D model of Earth.

The inclination of the earth's axis to plane of the orbit is 23½°.

  At 22 ½o North and South Latitude heat gain through insulation approximately equals heat loss through terrestrial radiation.

Statement 1: Crossing eastward across the International Date Line means you go into the previous day (repeat a day). TRUE. Statement 2: The IDL roughly divides the Pacific Ocean into two equal parts along the 180° meridian. TRUE. Statement 3: The IDL follows the 180° meridian with deviations for political boundaries. TRUE. Statement 4: Crossing westward does NOT repeat a day - you advance to the next day. FALSE. Therefore, statements 1, 2, and 3 are correct.

Earth's circumference is approximately 40,075 km at the equator. Dividing by 360 degrees gives about 111 km per degree. This is a standard approximation used in geography and navigation. 105 km (B) and 101 km (C) are too small, while 120 km (D) is too large.

This is the correct option.

This is the correct option. The Earth is not called a red planet, but is called a blue planet.