Geography Quiz: Solar system & the Earth & basics of Latitude and Longitude | 21 June, 2021

A large number of hypotheses were put forth by different philosophers and scientists regarding the origin of the earth.

• One of the earlier and popular arguments was by German philosopher Immanuel Kant.

• Mathematician Laplace revised it in 1796. It is known as Nebular Hypothesis.

Source: Fundamental of Physical Geography, Chapter – 2

One of the earlier and popular arguments was by German philosopher Immanuel Kant. Mathematician Laplace revised it in 1796. It is known as Nebular Hypothesis.

• The hypothesis considered that the planets were formed out of a cloud of material associated with a youthful sun, which was slowly rotating.

• Later in 1900, Chamberlain and Moulton considered that a wandering star approached the sun. As a result, a cigar-shaped extension of material was separated from the solar surface.
• As the passing star moved away, the material separated from the solar surface continued to revolve around the sun and it slowly condensed into planets.

Source: Fundamental of Physical Geography, Chapter – 2

Henrietta Leavitt discovered the relationship between the intrinsic brightness of a variable star and the time it took to vary in brightness, making it possible for others to estimate the distance of these faraway stars, conclude that additional galaxies exist, and begin mapping the Universe.

Source: https://www.khanacademy.org/humanities/big-history-project/big-bang/how-did-big-bang-change/a/henrietta-leavitt.

Out of the eight planets, mercury, Venus, earth and mars are called as the inner planets as they lie between the sun and the belt of asteroids the other four planets are called the outer planets.

• Alternatively, the first four are called Terrestrial, meaning earth-like as they are made up of rock and metals, and have relatively high densities.
• The rest four are called Jovian or Gas Giant planets. Jovian means Jupiter-like.

Source: Fundamental of Physical Geography, Chapter – 2

The difference between terrestrial and Jovian planets can be attributed to the following conditions:

• The terrestrial planets were formed in the close vicinity of the parent star where it was too warm for gases to condense to solid particles. Jovian planets were formed at quite a distant location.

• The solar wind was most intense nearer the sun; so, it blew off lots of gas and dust from the terrestrial planets. The solar winds were not all that intense to cause similar removal of gases from the Jovian planets.
• The terrestrial planets are smaller and their lower gravity could not hold the escaping gases.

Source: Fundamental of Physical Geography, Chapter – 2

Source: Fundamental of Physical Geography, Chapter – 2  

Source: Fundamental of Physical Geography, Chapter – 2

The Ekman spiral, named after Swedish scientist Vagn Walfrid Ekman (1874-1954) who first theorized it in 1902, is a consequence of the Coriolis Effect.

• When surface water molecules move by the force of the wind, they, in turn, drag deeper layers of water molecules below them.
• Each layer of water molecules is moved by friction from the shallower layer, and each deeper layer moves more slowly than the layer above it, until the movement ceases at a depth of about 100 meters (330 feet).

• Like the surface water, however, the deeper water is deflected by the Coriolis Effect-to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.
• As a result, each successively deeper layer of water moves more slowly to the right or left, creating a spiral effect.
• Because the deeper layers of water move more slowly than the shallower layers, they tend to “twist around” and flow opposite to the surface current.

Source: G C Leong

The International Date Line, established in 1884, passes through the mid-Pacific Ocean and roughly follows a 180 degrees longitude north-south line on the Earth.

• It is located halfway round the world from the prime meridian—the zero degrees longitude established in Greenwich, England, in 1852.
• The International Date Line functions as a “line of demarcation” separating two consecutive calendar dates.
• When you cross the date line, you become a time traveler of sorts! Cross to the west and its one day later; cross back and you’ve “gone back in time.”
• Despite its name, the International Date Line has no legal international status and countries are free to choose the dates that they observe.
• While the date line generally runs north to south from pole to pole, it zigzags around political borders such as eastern Russia and Alaska’s Aleutian Islands.

Source: G C Leong

Since the earth makes one complete rotation of 360° in one day or 24 hours, it passes through 15° in one hour or 1° in 4 minutes.

• The earth rotates from west to east, so every 15° we go eastwards, local time is advanced by 1 hour.
• If we know G.M.T, to find local time, we merely have to add or subtract the difference in the number of hours from the given longitude, as illustrated below.

• A simple memory aid for this will be East-Gain-Add (E.G.A.) and West-Lose-Subtract (W.L. S.).

Source: G C Leong