Questions on the moon?

Question

What is the size of the moon compared to Earth?
How was the moon formed?
Why does the moon not have an Atmosphere?
Does it not having an atmosphere affect high and low temperatures there?


One about Earth

Why cant the Earths craters be seen anymore?

Answer 1

Info below retrieved from Wikipedia

moon equatorial diameter = 3,476 km
earth equatorial diameter = 12,756 km
Then, the size of the moon compared to earth = 0.27

The inclination of the Moon's orbit makes it implausible that the Moon formed along with the Earth or was captured later; its origin is the subject of some scientific debate.The current theory on the moon's origin is that a very large object hit the earth some
4,527 ± 10 million years ago, causing a large amount of dust to orbit the earth. Eventually the dust accumulated to form the moon. The moon has many minerals which are similar to earth, and the moon lacks an molten iron core.

The gravity on the moon is very small, about 0.1654 that of earth. This would account for the lack of atmosphere.

The earth receives about 1,370 watts per square meter of solar energy, of which only about 1,000 watts per square meter reach the surface due to the adsorbtion of heat by the atmosphere.
Since the moon has no atmosphere, the temperatures on the moon swing higher/lower than the temperatures on the earth.
The min, mean and max temperatures on the surface of the moon (in Kelvin) are 40 K, 250 K, and 396 K respectively. The min, mean and max temperatures on the surface of earth are 185 K (-88 °C), 287 K (14 °C), and 331 K (58 °C) max respectively.

The apparent lack of craters on the earth is due to "plate tectonics", or the movement of the surfaces of the earth. Many craters were swallowed up when, say, the India plate moved underneath the plate which contains the Himalaya mountains.

Hope this helps!

Answer 2

The Moon, is more than one quarter the size of Earth itself (3,474 km diameter). Because of its smaller size, the Moon's gravity is one-sixth of the Earth's gravity.

At the time Earth formed 4.5 billion years ago, other smaller planetary bodies were also growing. One of these hit earth late in Earth's growth process, blowing out rocky debris. A fraction of that debris went into orbit around the Earth and aggregated into the moon

The Moon has no atmosphere because it did not have enough mass to keep an atmosphere from quickly escaping into space, and because it is geologically dead so the lost gases are not replenished.

Because there is no atmosphere to trap heat, the temperatures on the Moon are extreme, ranging from 100° C at noon to -173° C at night.

Since Earth has a atmosphere, Erosion is one of the major cause as to why craters cannot be seen. Also being geologically and ecologically active has caused craters to disappear ....
eg :- where there were plains the continental shift has created mountains as well as forests are known to exist in areas where we deserts right now

Answer 3

I'm not sure of the moon's size, but I think it is about 1/5 the size of earth.. They think the moon was formed by something hitting the earth. The "explosion" put a lot of stuff in orbit around earth, which eventually pulled together to form the moon. The moons gravity is such that (so small) it can't hold gases around it, which accounts for the wide temperature changes. There is a crater on earth, I think there is one in Arizona. With the climate being what it is on earth, erosion from wind and rain, earthquakes, and storms would have smoothed the craters down.

Answer 4

moon size =151720498.2857km
how?
diameter=3474 km
Calculationwill be the area of a sphere=surface area = 4pr2

so to get the area: =4*3.1428571428571428571428571428571*3474^2
=151720498.28571428571428571428571kilometers
0r =151720498.2857km

you dont have to retrive this anywhere just think. of the factors that caused this.
How was it formed.
three things hapened!
1.
you see when our solar system was created due to the explosion of a very massive star very large ammounts of rocks resedue were created. those since this rocks and planetary material were freely roaming around the solar radius some gravity (or you may call it the magnetic attraction of material of the same nature) of the residue caused them to come together and condence into one solid object. other materials that were far away to be pulled by the force of attraction just attracted their smaller resedue to from small planetary objects.

2. since there is alot of gravitational pull towards the center of our solar system (the sun) and its the bodies motion caused during the explosion. This created a centrifigual force on the bodies in whis their momentum together with the gravitational pull of the sun equaled thus causing the planets(all bodies within the reach of the suns and plannets gravitational pull otherwise the rest had floated away in space). to move in a fixed geosyncronious position away from the sun in a constant motion. thus creating the planets revolution round the sun leading to the invention of the idea of time in years.

3. objects too small and too far away to be attracted to the other bigger bodies(planets) came together to form other smaller planetary objects (moons) as they formed. They became larger thus were able to be atracted to the other larger bodies but due to their momentum and ernergy (kinetic) they could not combine with the other bodies but instead revolved round the planets also in a geogyncronious position due to the equality of the centripetal and centrifigual force.

But this was not supposed to hapen in galaxies. They were supposed to rotate away but there was something keeping them in a fixed path round. and it was descovered by a Physicist
called Fritz Zwicky aka crazy fritz ar refered to by his workmates.
and it is called the dark matter. But enough with that.

Why does the moon not have an atmosphere?
Reason!
The moon is soo small that it cannot sustain enough gravity to sustain air or other atmospheric particles within its surface thus when air is realised on the moon it just floats way to outerspace.

Does not having an atmosphere affect the surface temps?

It does infact the moon is soo cold you would freeze in an instant when exposed to the moon. That is one of the reasons why the astronuts have space suits (in order to regulate normal temps and pressue)

EARTH

Why cant the earths craters be seen anymore
Reason is simple. The atmosphere. since there is wind and moving fluid constantly the earths surface changes its form thus eralier evidence is completley wiped out. also due to the atmosphere commets1km diameter will have only a 50% chance of reaching the earth surface the smaller the commets the lesser the chanses. otherwise it will be disintergrated by the atmospheric molecues(air perticled) due to friction. unlike the moon which has no atmosphere thus the friction is reduced to almost 0 thus the commets bombard it like crazy.

Answer 5

Because of erosion on the earth, many of its craters have been rubbed out. Also, the atmopshere makes impact more dofficult, as most burn up during entry, so those few that make it were of adewuate size to survive

Answer 6

Moon
The Earth's natural satellite. United States and Soviet spacecraft have obtained lunar data and samples, and American astronauts have orbited, landed upon, and roved upon the Moon.

The Earth and Moon now make one revolution about their barycenter, or common center of mass (a point about 4670 km from the Earth's center), in 27d 7h 43m 11.6s. This sidereal period is slowly lengthening, and the distance (now about 60.27 earth radii) between centers of mass is increasing, because of tidal friction in the oceans of the Earth.

The Moon's present orbit is inclined about 5° to the plane of the ecliptic. As a result of differential attraction by the Sun on the Earth-Moon system, the Moon's orbital plane rotates slowly relative to the ecliptic (the line of nodes regresses in an average period of 18.60 years) and the Moon's apogee and perigee rotate slowly in the plane of the orbit (the line of apsides advances in a period of 8.850 years). Looking down on the system from the north, the Moon moves counterclockwise. It travels along its orbit at an average speed of nearly 0.6 mi/s (1 km/s) or about 1 lunar diameter per hour.

As a result of the Earth's annual motion around the Sun, the direction of solar illumination changes about 1° per day, so that lunar phases do not repeat in the sidereal period given above but in the synodic period, which averages 29d 12h 44m.

When the lunar line of nodes coincides with the direction to the Sun and the Moon happens to be near a node, eclipses can occur. See also Eclipse.

The relation between the Moon's shape and its mass distribution is very important to theories of lunar origin and the history of the Earth-Moon system. By radio altimetry, Apollo confirmed that the Moon's surface on the far side is higher on the average than the near side; that is, the center of mass is offset from the center of figure. The offset is about 2 km (1.2 mi) toward the Earth. These observations suggest that the Moon's crust is thicker on the far side than on the near side. The Clementine mission in 1994 extended measurements to nearly the whole Moon and revealed the depth of a huge basin on the southern far side.

The Moon's small size and low mean density result in surface gravity too low to hold a permanent atmosphere, and therefore it was to be expected that lunar surface characteristics would be very different from those of Earth. However, the bulk properties of the Moon are also quite different—the density alone is evidence of that. The Moon is too small to have compressed its silicates into a metallic phase by gravity; therefore, if it has a dense core at all, the core should be of nickel-iron. Available data suggest that the Moon's iron core may have a diameter of at most a few hundred kilometers.

As can be seen from the Earth with the unaided eye, the Moon has two major types of surface: the dark, smooth maria and the lighter, rougher highlands. Photography by spacecraft shows that, for some unknown reason, the Moon's far side consists mainly of highlands. Both maria and highlands are covered with craters of all sizes. Numerous different types of craters can be recognized. Most prominent at full moon are the bright ray craters whose grayish ejecta appear to have traveled for hundreds of miles across the lunar surface. Observers have long recognized that some erosive process has been and may still be active on the Moon. Bombardment of the airless Moon by meteoritic matter and solar particles, and extreme temperature cycling, are now considered the most likely erosive agents, but local internal activity is also a possibility.

The lunar mountains, though very high (26,000 ft or 8000 m), are not extremely steep, and lunar explorers see rolling rather than jagged scenery. Though a widespread network of fault traces is visible, there is no evidence on the Moon of the great mountain-building processes seen on the Earth.

Basins on the Moon's near side, namely, Imbrium, Serenitatis, and Crisium, appear fully flooded. These were maria created by giant impacts, followed by subsidence of the ejecta and (probably much later) upwelling of lava from inside the Moon. Examination of small variations in Lunar Orbiter motions has revealed that each of the great circular maria is the site of a positive gravity anomaly (excess mass). The old argument about impact versus vulcanism as the primary agent in forming the lunar relief appears to be entering a new, more complicated phase with the confirmation of extensive flooding of impact craters by lava on the Moon's near side, while on the far side, where the crust is thicker, the great basins remain mostly empty.

In some of the Moon's mountainous regions bordering on the maria are found sinuous rilles (see illustration). These winding valleys were shown in Lunar Orbiter pictures to have an exquisite fineness of detail. No explanation for them yet offered has proved entirely convincing

Answer 7

http://en.wikipedia.org/wiki/Moon
This should answer all your moon questions.

And your Earth question... Erosion.

Answer 8

It is held that more than 4.5 billion years ago, the surface of the Moon was a liquid magma ocean. Scientists think that one component of lunar rocks, called KREEP (potassium, rare earth elements, and phosphorus), represents the last chemical remnant of that magma ocean. KREEP is actually a composite of what scientists term incompatible elements: those that cannot fit into a crystal structure and thus were concentrated in the remaining magma. For the researchers, KREEP is a convenient tracer, useful for reporting the story of the volcanic history of the lunar crust and chronicling the frequency of impacts by comets and other celestial bodies.

The lunar crust is composed of a variety of major elements, such as oxygen, silicon, magnesium, iron, calcium, aluminium, but also contains important quantities of secondary elements, including titanium, uranium, thorium, potassium, and hydrogen. The Moon has a mean density of 3,346.2 kg/m³, making it the second densest moon in the solar system, after Io.

A complete global mapping of the Moon for the abundance of major and minor elements has not yet been performed. However, some spacecraft have done so for portions of the Moon, or for certain elements. In particular, a gamma-ray spectrometer onboard the spacecraft Lunar Prospector has determined near-global abundances of iron, calcium, aluminum, magnesium, titanium, potassium, thorium, uranium, and hydrogen. The Clementine spacecraft has obtained near-global abundances for iron and titanium, but at a much higher spatial resolution.


Landscape

Lunar crater Daedalus. NASA photo.
Tycho crater on the Moon. It is about 85 kilometres across.When observed with Earth based telescopes, the Moon can be seen to have some 30,000 craters having a diameter of at least 1 km, but close up observation from lunar orbit reveals a multitude of ever smaller craters. Most are hundreds of millions or billions of years old, and the lack of an atmosphere, weather and recent geological processes ensures that many of them have remained relatively well preserved in comparison to their terrestrial counterparts. In the lunar terrae, it is indeed impossible to add a crater of any size without obliterating another. The largest crater on the Moon, and indeed the largest known crater within the solar system, is the South Pole-Aitken basin. This crater is located on the far side, between the South Pole and equator, and is some 2,240 kilometres in diameter, and 13 kilometres in depth.[5]

The dark and relatively featureless lunar plains are called maria, Latin for seas, since they were believed by ancient astronomers to be water-filled seas. They are actually vast ancient basaltic lava flows, many of which filled the topographic depressions associated with large impact basins (Oceanus Procellarum is a major exception in that it does not correspond to any known impact basin). The lighter-colored highlands are called terrae. Maria are found almost exclusively on the lunar nearside, with the lunar far side having only a few scattered patches.

Blanketed atop the Moon's crust is a highly comminuted and "impact gardened" surficial layer called regolith. Both the crust and regolith are unevenly distributed over the Moon. The crust is on average about 50 km thick (though this is uncertain by about ±15 km), and it is widely believed that the far-side crust is on average thicker than the near side by about 15 km. [6]. The regolith varies from 3 to 5 metres (10 to 16 ft) deep in the maria to 10 to 20 metres (33 to 66 ft) deep in the highlands.

Using images taken by the Clementine mission, it appears that four mountainous regions on the rim of the 73 km-wide Peary crater at the Moon's north pole remain illuminated for the entire lunar day. These unnamed mountains of eternal light are possible due to the Moon's extremely small axial tilt, which also gives rise to permanent shadow at the bottoms of many polar craters. No similar regions of eternal light exist at the less mountainous south pole, although the rim of Shackleton crater is illuminated for 80% of the lunar day. Clementine's images were taken during the northern lunar hemisphere's summer season, and it remains unknown whether these four mountains are shaded at any point during their local winter season.


Presence of water
Over time, comets and meteoroids continuously bombard the Moon. Many of these objects are water-rich. Energy from sunlight splits much of this water into its constituent elements hydrogen and oxygen, both of which usually fly off into space immediately. However, it has been hypothesized that significant traces of water remain on the Moon, either on the surface, or embedded within the crust. The results of the Clementine mission suggested that small, frozen pockets of water ice (remnants of water-rich comet impacts) may be embedded unmelted in the permanently shadowed regions of the lunar crust. Although the pockets are thought to be small, the overall amount of water was suggested to be quite significant — 1 km³.

Some water molecules, however, may have literally hopped along the surface and become trapped inside craters at the lunar poles. Due to the very slight "tilt" of the Moon's axis, only 1.5°, some of these deep craters never receive any light from the Sun — they are permanently shadowed. Clementine has mapped[7] craters at the lunar south pole[8] which are shadowed in this way. It is in such craters that scientists expected to find frozen water. Water ice can be mined and then split into hydrogen and oxygen by solar panel-equipped electric power stations or a nuclear generator. The presence of usable quantities of water on the Moon is an important factor in rendering lunar habitation cost-effective, since transporting water (or hydrogen and oxygen) from Earth would be prohibitively expensive.

The equatorial Moon rock collected by Apollo astronauts contained no traces of water. In the permanently shadowed regions, however, Lunar Prospector results indicate the presence of hydrogen due to its neutron signature. This corroborated radar reflections from the Clementine probe, leading some to postulate that the hydrogen was in the form of water ice (http://lunar.arc.nasa.gov/results/ice/eureka.htm). Recent radar observations with the Arecibo planetary radar showed that the Clementine radar returns were from rocks ejected from young craters, rocks which did not follow permanently-shadowed crater floors. This indicates that the neutron results are primarily from hydrogen in forms other than ice, such as trapped hydrogen molecules or organics. However, the researchers do not exclude the possibility of minor ice sites.


Magnetic field
Compared to that of Earth, the Moon has only a very weak external magnetic field. Other major differences are that the Moon does not currently have a dipolar magnetic field (as would be generated by a geodynamo in its core), and the magnetizations that are present are almost entirely crustal in orgin. One hypothesis holds that the crustal magnetizations were acquired early in lunar history when a geodynamo was still operating. The small size of the lunar core, however, is a potential obstacle to this theory. Alternatively, it is possible that on airless bodies such as the Moon, transient magnetic fields could be generated during impact processes. In support of this, it has been noted that the largest crustal magnetizations appear to be located near the antipodes of the largest impact basins.


Atmosphere
The Moon has a relatively insignificant and tenuous atmosphere. One source of this atmosphere is outgassing — the release of gases, for instance radon, which originate deep within the Moon's interior. Another important source of gases is the solar wind, which is briefly captured by the Moon's gravity.


Eclipses

The Moon as illuminated by Earthshine. The brightest crescent is in direct sunlight; the upper portion is lit by light reflected from Earth.Main article: Eclipse
Eclipses happen only if Sun, Earth, and Moon are lined up. Solar eclipses can only occur near a new moon; lunar eclipses can only occur near a full moon.

The angular diameters of the Moon and the Sun as seen from Earth overlap in their variation, so that both total and annular solar eclipses are possible. In a total eclipse, the Moon completely covers the disc of the Sun and the solar corona becomes visible to the naked eye.

Since the distance between the Moon and the Earth is very slightly increasing over time, the angular diameter of the Moon is decreasing. This means that hundreds of millions of years ago the Moon could always completely cover the Sun on solar eclipses so that no annular eclipses were possible. Likewise, about 600 million years from now (assuming that the angular diameter of the Sun will not change), the Moon will no longer cover the Sun completely and total eclipses will not occur.


Occultation of stars
Main article: Occultation
The Moon is continuously blocking our view of the sky directly behind it. The Moon blocks about a 1/2 degree wide circular area. When a bright star or planet passes behind the Moon it is occulted or hidden from view. A solar eclipse is an occultation of the Sun. Because the Moon is close to Earth, occultations of stars are not visible everywhere. Because of the moving nodes of the lunar orbit, each year different stars are occulted.


Observation of the Moon

Moon surface. NASA photo.See also: Lunar phase, New moon, Full moon, Earthshine, and Moonlight
During the brightest full moons, the Moon can have an apparent magnitude of about −12.6. For comparison, the Sun has an apparent magnitude of −26.8. When the Moon is in a quarter phase, its brightness is not one half of a full Moon. It is only about 1/10 of that, because the amount of solar radiation reflected towards the Earth is highly reduced by the shadows projected by the higher parts of the Moon over the lower ones.

The Moon appears larger when close to the horizon. This is a purely psychological effect (see Moon illusion). The angular diameter of the Moon from Earth is about one half of one degree, and is actually about 1.5% smaller when the Moon is near the horizon than when it is high in the sky (because it is farther away by up to 1 Earth radius).


Halo around MoonAnother quirk of the visual system causes us to see the Moon as almost pure white, when in fact it reflects only about 7% of the light falling on it (about as dark as a lump of coal). It has a very low albedo. Color constancy in the visual system recalibrates the relations between colors of an object and its surroundings; however, there is nothing next to the Moon to reflect the light falling on the Moon, therefore it is perceived as the brightest object visible. We have no standard to compare it to. An example of this is that, if you used a narrow beam of light to illuminate a lump of coal in a dark room, it would look white. If you then broadened the beam of the light source to illuminate the surroundings, it would revert to black.