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“
Catch a star ! “ |
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THE MOON
SUMMARY
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III. Physical characteristics of the Moon IV. Tides VI. Experiments 1 -Procedure 2 - Observations, acquisition and image processing 3 - Assumptions 5 - Conclusions VII. Personnal
conclusion VIII. References
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Three theories are proposed to explain the
origin of the Moon :
1 - The theory of Fission
: The rotation of the Earth was 10
times faster than today and under the effect of the tides of the Sun, parts of
the external layers would have been rejected and would have accumulated to form
the Moon.
2 - The theory of capture: the Moon would have
been formed by agglomeration of the matter of a protoplanetary disc in which
metals were missing.
3 - The theory of
collision: a giant asteroid (8 times
as large as the Moon) hit the Earth on its side. At the time of the
"crash" parts of the earth’s crust was projected into space, forming
the Moon, whereas the metal core of the asteroid agglomerated with that: of the
Earth by fusion.
from” Astronomie et
astrophysique”
The first historic observation :
The first man who really observed the Moon was Galileo
because he observed the Moon with a refractor of 30 mm aperture.
II- Discovery of the Moon
The discovery of the moon was
realised by observations from Earth and with space probes.
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year |
country |
results |
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Luna-1 |
1959 |
U.S.S.R. |
By flight |
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Luna-2 |
1959 |
U.S.S.R. |
crash |
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Luna-3 |
1959 |
U.S.S.R. |
Photographs of hidden side of the moon |
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Ranger-7 |
1964 |
The |
Photographs of hidden side of the moon crash |
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Luna-9 |
1966 |
U.S.S.R. |
First
landing on the moon |
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Apollo-11 |
1969 |
The |
First
manned landing on the moon, return of
samples |
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Luna-16 |
1970 |
U.S.S.R. |
Automatic return of
samples |
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Luna-17 |
1970 |
U.S.S.R. |
Lunokhod-1:remote
controlled moon jeep |
III - PHYSICALS CHARACTERISTICS
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Position: |
- single Natural satellite
of the Earth |
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Movement around the Earth: |
- average distance to the Earth is of 384400km
is approximately 0.0026 A.U. -
orbital Eccentricity: 0.054° - Period of revolution: 27.32 days - Slope of the orbit: 5.1° in comparison with the Terrestrial
orbit |
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Rotational movement: |
- the period of rotation of 27.32 days is the
same one as its period of revolution - relative flatness is 0.0006 - slope of the equator compared to the
orbit: 2.6° |
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Mass, size and density: |
- equatorial diameter: 3476 km - volume:
2.20*10-3 km2 - mass:
7.35*1022kg - fields gravitational: 1.57N/kg - escape velocity: 2.4km.s-1 - true density: 3.36 - decompressed density: 3.35 - gravity has the equator 1.62m.s-2 |
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Temperature on the surface: |
- extreme:
day : 127°C (400K) night : -173 °C (1OOK ) - average:
0°C ( 273 K ) |
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Albedo: |
-0.07 |
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Atmosphere: |
- none |
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Magnetic field: |
- none |
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Tourist information: |
- time of radio transmission with the Earth is
of approximately 1.3s |
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Tides
count among the most significant variations In the height of the sea. The
combined attraction of the Moon and the Sun, is at the origin of this
phenomena and its variations. The
Moon and the Sun attract the Earth and its oceans which become deformed.
Water will accumulate
where attraction is maximum, i.e. at the point
of the sphere located closest to the star. Moreover,
thanks to the speed of movement, a centrifugal force opposite to attraction
maintains the Earth on its orbit. This centrifugai force pushes back the
water, which thus will accumulate contrary to the Star.
Moreover, one knows that the Moon is seldom in the equatorial plan of the
Earth, thus, for the same latitude,
the amptude will not be the same for the two daily tides. Sometimes there is only one
tide per day. |
from”
Astronomie et astrophysique” |
Titan, the greatest satellite of Saturn, is very
interesting because it can be compared to Earth at this origin.
The atmosphere is very rich, actually scientists
suppose that consists of clouds of ammoniac, nitrogen and methane or could say
“among over grasses”. They are waiting with impatience the landing of the
Huygens spacecraft.
We can note that diameter and mass are similar at the
moon but the principal difference is about atmosphere. The atmosphere of Titan
is very important with organic molecules like N2 and CH4.
Principals characteristics of Titan and comparison
with moon :
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Datas |
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Comparison
with M oon |
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position |
1 222 000
km from Saturn |
3,2 x
distance Earth- Moon |
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Period
of revolution |
15,96
days |
27,32
days |
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diameter |
5150 km |
1,48 x |
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volume |
7,2.1010
km3 |
3,3 x |
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mass |
1,3.1023
kg |
1,77 x |
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Density |
1,9 |
0,57 x |
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Atmosphere -
pressure -
temperature -
composition |
1,5 bar - 183
°C ( 90 K ) 90% of
N2 ; 10% of CH4 ; clouds of hydrocarbures |
None - 173
°C ( 100 K ) none |
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albedo |
0,2 |
0,07 |
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This image
taken by Cassini's visual and infrared
mapping spectrometer clearly shows surface features on Titan. It is a
composite of false-color images taken at three infrared wavelengths: 2 microns
(blue); 2.7 microns (red); and 5 microns (green). A methane cloud can be seen
at the south pole (top of image). This picture was obtained as Cassini flew
by Titan at altitudes ranging from 100,000 to 140,000 kilometers (88,000 to
63,000 miles), less than two hours before the spacecraft's closest approach.
The inset picture shows the landing site of Cassini's piggybacked Huygens
probe. Credit:
NASA/JPL/University of Arizona |
VI- Experiments
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After preparatory meetings we chose the evening of October 21, 2004 to take our
images. All the photographs were taken by us with the assistance of a
professor of the club of astronomy. This evening
was not selected randomly, because to make a good lunar study in the evening,
we needed to take pictures during the first quarter, while having a clear
sky. This evening was “ideal”. After having gathered the material in the course of
the day, we began the evening at 19h00. After installing the material, we
could begin the observation from 19h18. With material of a Perl Vixen
refractor 150mm in diameter and 750mm focal distance, we observed the Moon.
The webcam “toucam pro” was used to carry out the videos, several
intermediaries were used, like the lens of Barlow 2X, a reducer of focal of
0.5X, a filter cantiniuum or a IR-UV filter, (it cuts infra-red and
ultra-violet at the same time). |
Pierre
and the telescope |
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We encountered several difficulties that evening. Given that this refractor is equipped with a motorised
mounting aided by automatic follow-up, we first had to mount it, that is align
the refractor’s axis of rotation with the earth’s. During the first
observation we experienced a lot of turbulence which complicated the
focusing. We also realised that focusing produced vibrations which were
accentuated by the refractor zoom. Thus, the more we zoomed, the stronger the
vibrations were (use of barlow). Furthermore, the wind created vibrations on
the refractor. The turbulence was therefore stronger because, the moon being
low caused the atmosphere to be thicker. |
Webcam
and this carry-eyepiece adapter |
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We produced a score of films of the moon that required
formatting in order to be released. The formatting For this step we used a program called “registax
V1.1beta” which is free and available on the internet. Formatting at a film
file-type.avi is carried out in 4 stages:
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2 - Observations
At the time of our
observation, we could notice that there were various kinds of craters. Some have a central peak located at the center
of the crater, others have their crown in the shape of steps, others have an extremely flat bottom... All these differences let suppose that all
these craters have many different origins.
Thus we will raise some assumptions, which we will explain thereafter by
comparing the results of our experiments with the craters of the Moon that we
took.
We have observed that the
moon crater could have various forms shown on this photography: