Question

Earth and Moon Questions

1. What does the term moon mean? How big is the moon (diameter, volume, comparison to earth)?

2. Describe the main surface features of the moon?

3. What are some of the more important discoveries of the Apollo program? Does the flag fly on the moon?

4. What is the theory of the origin of the moon?

5. What are the major effects of the moon on the earth?

6. What is an eclipse? Describe the 2 kinds.

7. What are time zones?   How do they relate to the earth’s structure? What function does the International Date Line serve in relation to time?

8. What are the major plates of the earth? What are types of plate boundaries?

9. What are the parts of the structure of the earth’s atmosphere? Describe each layer.

Answer 1

A moon is defined to be a celestial body that makes an orbit around a planet, including the eight major planets, dwarf planets, and minor planets.

The diameter of moon is 3474.2 km whereas the diameter of Earth is 12,742 km. Therefore, moon is approximately one fourth the size of our planet.

The volume of the Moon is 21.9 billion cubic km , but the volume of the Earth is more like 1 trillion cubic kilometers. So the volume of the Moon is only 2% compared to the volume of the Earth.

Main features of moon surface :

​​​​​​​​​​1) Impact craters : are found on the surfaces of all the terrestrial planets and satellites.Because of the Moon's lack of water, atmosphere, and tectonic plates, there is little erosion, and craters are found that exceed two billion years in age. When a solid object strikes a planetary surface at high speed an extremely powerful shockwave spreads out from the impact site. This compresses the rocks and make it deform so that it flows like a liquid. As the shockwave radiates outwards , decompressed material behind it is thrown upward and outward excavating a volume of material much larger than that of the impactor. The lartest craters with diameter over 200 km are known as BASINS.The South Pole-Aitken (SPA) basin is the largest and oldest recognized impact basin on the moon

2) Highland : Most of the crust of the Moon (83%) consists of silicate rocks called anorthosites; these regions are known as the lunar highlands. They are made of relatively low-density rock that solidified on the cooling Moon like slag floating on the top of a smelter.

3) maria : The lunar maria are large, dark, basaltic plains on Earth's Moon, formed by ancient volcanic eruptions. They are less reflective than the "highlands" as a result of their iron-rich composition, and hence appear dark to the naked eye. The maria cover about 16% of the lunar surface, mostly on the side visible from Earth. The few maria on the far side are much smaller, residing mostly in very large craters.

The Apollo 11 mission showed that the Moon differentiated early and was magmatically active at least until 3.7 billion years ago. (Additional Apollo samples and lunar meteorites indicate igneous activity as recently as about a billion years ago.) Planets did not form cold. The magma ocean idea has been routinely extended to other terrestrial planets and even large asteroids.

No the flag will not fly on the moon since there is no atmosphere , so there would be no wind to blow.

The standard giant-impact hypothesis suggests that the Mars-sized body, called Theia, impacted the proto-Earth, creating a large debris ring around Earth, which then accreted to form the Moon. This collision also resulted in the 23.5° tilted axis of the Earth, thus causing the seasons.

The moon's gravitational pull causes two bulges of water on the Earth's oceans—one where ocean waters face the moon and the pull is strongest and one where ocean waters face away from the moon and the pull is weakest ; TIDES . The pull of the moon is also slowing the Earth's rotation, an effect known as tidal braking, which increases the length of our day by 2.3 milliseconds per century.

An eclipse is an astronomical event that occurs when one celestial object moves into the shadow of another. The two kinds of eclipse are :-

1. SOLAR ECLIPSEB : A solar eclipse occurs when a portion of the Earth is engulfed in a shadow cast by the Moon which fully or partially blocks sunlight. This occurs when the Sun, Moon and Earth are aligned.

2. LUNAR ECLIPSE : Lunar eclipses occur when Earth's shadow blocks the sun's light, which otherwise reflects off the moon. There are three types — total, partial and penumbral — with the most dramatic being a total lunar eclipse, in which Earth's shadow completely covers the moon.

A time zone is a region of the globe that observes a uniform standard time for legal, commercial, and social purposes. As the Earth rotates on its axis, it moves about 15 degrees every 60 minutes. After 24 hours, it has completed a full circle rotation of 360 degrees. The scientists used this information to divide the planet into 24 sections or time zones. Each time zone is 15 degrees of longitude wide.

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.

The outer shell of the earth, the lithosphere, is broken up into tectonic plates. The seven major plates are the African plate, Antarctic plate, Eurasian plate, Indo-Australian plate, North American plate, Pacific plate and South American plate.

There are three main types of plate boundaries:

• Convergent boundaries: where two plates are colliding. Subduction zones occur when one or both of the tectonic plates are composed of oceanic crust.
• Divergent boundaries – where two plates are moving apart.
• Transform boundaries – where plates slide passed each other.

The Earth's atmosphere is comprised of layers based on temperature. These layers are the troposphere, stratosphere, mesosphere and thermosphere. A further region at about 500 km above the Earth's surface is called the exosphere.

Troposphere : This is the lowest part of the atmosphere - the part we live in. It contains most of our weather - clouds, rain, snow.

The lowest part of the troposphere is called the boundary layer. This is where the air motion is determined by the properties of the Earth's surface. Turbulence is generated as the wind blows over the Earth's surface, and by thermals rising from the land as it is heated by the sun. This turbulence redistributes heat and moisture within the boundary layer, as well as pollutants and other constituents of the atmosphere.

The top of the troposphere is called the tropopause. This is lowest at the poles, where it is about 7 - 10 km above the Earth's surface. It is highest (about 17 - 18 km) near the equator.

2) the stratosphere : This extends upwards from the tropopause to about 50 km. It contains much of the ozone in the atmosphere. The increase in temperature with height occurs because of absorption of ultraviolet (UV) radiation from the sun by this ozone. Temperatures in the stratosphere are highest over the summer pole, and lowest over the winter pole.

3) the mesosphere : The region above the stratosphere is called the mesosphere. Here the temperature again decreases with height, reaching a minimum of about -90°C at the "mesopause".

4) The Thermosphere and Ionosphere :

The thermosphere lies above the mesopause, and is a region in which temperatures again increase with height. This temperature increase is caused by the absorption of energetic ultraviolet and X-Ray radiation from the sun.

The region of the atmosphere above about 80 km is also caused the "ionosphere", since the energetic solar radiation knocks electrons off molecules and atoms, turning them into "ions" with a positive charge.

5) The Exosphere:

The region above about 500 km is called the exosphere. It contains mainly oxygen and hydrogen atoms, but there are so few of them that they rarely collide - they follow "ballistic" trajectories under the influence of gravity, and some of them escape right out into space.