Catch a Star 2002

Fig.1: Travelling to
the Moon

Fig. 2: On the Moon

 

Fig. 3: On the Moon

1.Introduction:
We are on the Moon! We reached it after a four-day trip that started from
that extremely beautiful blue globe where our home is. That globe is our
world- the world of humans who has started leaving it because they wanted
to reach the Moon, planets and distant stars.

2. Historical information:
In the far past people worshiped the Moon. Different nations called it on different ways.
It was he personified as a goddess. Later she wass identified with Diana and Hecate. She was equivalent to the Greek Selene.

Fig. 4: The Moon

She resembled a young woman with an extremely white face who traveled on a silver chariot drawn by two horses. She wais often shown riding a horse or a bull. Selene was said to wear robes, carry a torch, and wear a half moon on her head. She was not one of the twelve great gods on Olympus, however she was the moon goddess. After her brother Helios completed his journey across the sky, she began hers. Before Selene's journey across the night sky she bathed in the sea.
Selene wais a favorite of many poets, especially love poets :-)! A moonlit night brings the feeling of romance. It was said that Selene's moon rays fall upon sleeping mortals, and her kisses fell upon her love, Endymion.
The Moon is the only one space object that was known that it turns around the Earth even from ancient times.
During II century AC Hiparhus determined the declination of the Moon's orbit to the plane of the ecliptic and explained many of the peculiarities of the movement of the Moon. He made a very good theory for the movement of the Moon and for lunar and solar eclipses.
The theory about movement of the Moon around the Earth was developed further by the astronomer Claudius Ptolemy (II century) and he devoted one book from his huge work Almagest to the Moon. This theory was improved by sir Isaac Newton.
Nowadays the parameters of the Moon's orbit are known with very good accuracy. The Moon makes its full turning around the Earth for 27, 32155 days or 27days 7 hours 43 minutes. This is called siderian month ( the period of movement of the Moon that is relative to stars).
The period of change of the Moon phases or sidonic month is longer that the siderian one. It is 29,530588 days or 29 days 12 hours and 44 minutes.

3.The Moon in the past:The Origin of the Moon
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
M moon. This is a good hypothesis because:
· the Earth has a large iron core, but the moon does not. This is because Earth's
iron had already drained into the core by the time the giant impact happened. Therefore, the debris blown out of both Earth and the impactor came from their iron-depleted, rocky mantles. The iron core of the impactor melted on impact and merged with the iron core of Earth, according to computer models.
· Earth has a mean density of 5.5 grams/cubic centimeter, but the moon has a density of only 3.3g/cc. The reason is the same, that the moon lacks iron.
· The moon has exactly the same oxygen isotope composition as the Earth, whereas Mars rocks and meteorites from other parts of the solar system have different oxygen isotope compositions. This shows that the moon formed form material formed in Earth's neighborhood.
· If a theory about lunar origin calls for an evolutionary process, it has a hard time explaining why other planets do not have similar moons. (Only Pluto has a moon that is an appreciable fraction of its own size.) Our giant impact hypothesis had the advantage of invoking a stochastic
catastrophic event that might happen only to one or two planets out of nine.
The earlier ideas are:
· One early theory was that the moon is a sister world that formed in orbit around
Earth as the Earth formed. This theory failed because it could not explain why
the moon lacks iron.
· A second early idea was that the moon formed somewhere else in the solar
system where there was little iron, and then was captured into orbit around Earth.
This failed when lunar rocks showed the same isotope composition as the Earth.
· A third early idea was that early Earth spun so fast that it spun off the moon.
This idea would produce a moon similar to Earth's
The theory come from Russian astrophysicist named V. S. Safronov.
Picking up on Safronov's general ideas, two astronomers, Hartmann and Davis
ran calculations of the rate of growth of the 2nd-largest, 3rd largest, etc., bodies
in the general vicinity of Earth, as the Earth itself was growing. Just as the
asteroid belt today has a largest asteroid (Ceres) at a 1000 km diameter, and
several smaller bodies in the 300-500 km diameter range, the region of Earth's
orbit would have had several bodies up to about half the size of the growing Earth.
The idea was that in the case of Earth (but not the other planets) the impact happened late enough, and in such a direction relative to Earth's rotation, that abundant enough middle material was thrown out to make a moon. mantle, but it failed when analysis of the total angular momentum and energy involved indicated that the present Earth-moon system could not form in this way.
The theory is develop very interesting. After the theory was first presented in 1974 at a conference on satellites, Harvard researcher A. G. W. Cameron rose to say that he and William Ward were also working on the same idea, but coming at it from a different motivation -- the study of angular momentum in the system -- and that they had concluded the impacting body had to be roughly Mars size (a third or half the size of Earth). Cameron and Ward published an abstract on this idea at the Lunar Science conference in 1976. Some work was done by Thompson and Stevenson in 1983 about the formation of moonlets in the disk of debris that formed around Earth after the impact. However, in general the theory languished until 1984 when an international meeting was organized in Kona, Hawaii, about the origin of the moon. At that meeting, the giant impact hypothesis emerged as the leading hypothesis and has remained in that role ever since. Dr. Michael Drake, director of the University of Arizona's Planetary Science Department, recently described that meeting as perhaps the most successful in the history of planetary science.

 

 

4.The Moon in the future: Movement of the Moon away from the Earth
The gravitational forces between the Earth and the Moon cause some interesting
effects. The most obvious is the tides. The Moon's gravitational attraction is
stronger on the side of the Earth nearest to the Moon and weaker on the opposite
side. Since the Earth, and particularly the oceans, is not perfectly rigid it is stretched
out along the line toward the Moon. From our perspective on the Earth's surface
we see two small bulges, one in the direction of the Moon and one directly
opposite. The effect is much stronger in the ocean water than in the solid crust so
the water bulges are higher. And because the Earth rotates much faster than the
Moon moves in its orbit, the bulges move around the Earth about once a day giving two high tides per day. (This is a greatly simplified model; actual tides, especially near the coasts, are much more complicated.)
But the Earth is not completely fluid, either. The Earth's rotation carries the Earth's bulges slightly ahead of the point directly beneath the Moon. This means that the force between the Earth and the Moon is not exactly along the line between their centers producing a torque on the Earth and an accelerating force on the Moon. This causes a net transfer of rotational energy from the Earth to the Moon, slowing down the Earth's rotation by about 1.5 milliseconds/century and raising the Moon into a higher orbit by about 3.8 centimeters per year!!!
We calculated that after 100 million years the Moon will have moved away from the Earth at a distance of 3 800km.

5. Guide for moon walkers :-)
Main important information about the Moon:
Data about the planet
Equatorial radius: 1,737.4(km)
Mean distance from Earth: 384,400(km)
Mass : 7.349õ1022(kg)
Mean density: 3.34 (gm/cm3)
Rotational period: 27.32166 (days)
Orbital period: 27.32166 (days) Fig12
Orbital inclination (degrees): 5.1454
Orbital eccentricity: 0.0549
Average length of lunar day: 29.53059(days)
Mean orbital velocity: 1.03 (km/sec)
Equatorial surface gravity: 1.62 (m/sec^2)
Equatorial escape velocity: 2.38 (km/sec)
Visual geometric albedo: 0.12
Magnitude (Vo) : -12.74
Very important information for moon hitchhikers:
Mean surface temperature (day): 107°C Fig13
Mean surface temperature (night): -153°C
Maximum surface temperature: 123°C
Minimum surface temperature: -233°C

Inner structure of the Moon:
The density of the Moon is 3340kg/m3, which is equal to the density of the Earth's mantle. This means that our satellite either doesn't have a thick iron nucleus, or it is too small. Four nuclear powered seismic stations were installed during the Apollo project to collect seismic data about the interior of the Moon. There is only residual tectonic activity due to cooling and tidal forcing, but other moonquakes have been caused by meteor impacts and artificial means, such as deliberately crashing the Lunar Module into the moon. The results have shown the Moon to have a crust 60 kilometers (37 miles) thick at the center of the near side. If this crust is uniform over the Moon, it would constitute about 10% of the Moon's volume as compared to the less than 1% on Earth.
The seismic determinations of a crust and mantle on the Moon indicate a layered planet with differentiation by igneous processes. There is no evidence for an iron-rich core unless it were a small one. Seismic information has influenced theories about the formation and evolution of the Moon and for Moon walkers!

Moon mineralology (how did scientists receive the information):
Expedition of American astronauts on the Moon that carried on the Earth moon
rocks caused the creation of a new science- science about the Moon minerals.
Using the contents of radioactive isotopes it was determined the age of the
Moon minerals - they are more that 4.6 milliard years old. The analyses of Moon
rocks allowed scientists to determine very accurately what is the difference
between seas and continents. It was understood that seas are covered with
basalt. They have a circular form and smooth surface. Not only radio isotopic analyses but and the small number of craters in the seas showed that the seas are relatively younger. This shows that the "seas" were formed as a result of impressive ejections of lava coming from the Moon womb. So the Moon seas were real seas but they contained not water but lava. The youngest sea is the sea of rains- only 3.87 milliard years old, while the other seas were formed 4 milliard years ago.

The Surface of the Moon: The dark, relatively lightly cratered maria
cover about 16% of the lunar surface and is concentrated on the nearside
of the Moon, mostly within impact basins. This concentration may be
explained by the fact that the Moon's center of mass is offset from its
geometric center by about 2 kilometers (1.2 miles) in the direction of
Earth, probably because the crust is thicker on the farside. It is possible,
therefore, that basalt magmas rising from the interior reached the surface
easily on the nearside, but encountered difficulty on the farside. Mare
rocks are basalt and most date from 3.8 to 3.1 billion years. Some
fragments in highland breccias date to 4.3 billion years and hight
resolution photographs suggest some mare flows actually embay young craters and may thus be as young as 1 billion years. The maria average only a few hundred meters in thickness but are so massive they frequently deformed the crust underneath them which created fault-like depressions and raised ridges.
The Moon has fascinated mankind throughout the ages. By simply viewing with the naked eye, one can discern two major types of terrain: relatively bright highlands and darker plains. By the middle of the 17th century, Galileo and other early astronomers made telescopic observations, noting an almost endless overlapping of craters. It has also been known for more than a century that the Moon is less dense than the Earth. Although a certain amount of information was ascertained about the Moon before the space age, this new era has revealed many secrets barely imaginable before that time. Current knowledge of the Moon is greater than for any other solar system object except Earth. This lends to a greater understanding of geologic processes and further appreciation of the complexity of terrestrial planets.

Moon map
If we look at the Moon's surface, we will see dark spots with
different shapes of seas and light spots that are craters. The Italian
scientist Dzovani Richoly gave names to the dark places that are
used nowadays as well: Oceanus Procellarum(Ocean of Storms),
Mare Imbrium(Sea of Rains), Mare Cognitum(Known Sea),
Mare Humorum (Sea of Moisture), Mare Nubium (Sea of Clouds)
, Mare Frigoris(Sea of Cold), Mare Serenitatis(Sea of Serenity),
Mare Vaporum(Sea of Vapors), Mare Tranquillitatis(Sea of
Tranquillity), Mare Nectaris(Sea of Nectar), Mare Humboldtianum,
Mare Crisium(Sea of Crises), Mare Fecunditatis(Sea of Fecundity),
Mare Marginis, Mare Smythii, Mare Australe, Mare Moscoviense,
Mare Ingenii, Mare Orientale, Mare Spumans (Sea of Foam),
-Sinus Aestuum (Bay of Seething) , Mare Frigoris (Sea of Cold),
Mare Fecunditatis (Sea of Fecundity), Mare Nubium (Sea of Clouds)…
On the dark spots there are many craters. The word crater is Latin and means a glass. Richoly offered craters to be named after scientist and that's why there are craters called Platoon, Aristotle, Galileo, etc.
Each moon walker has to know the Moon map very well. It is very easy to be found the larger objects- the seas on- the map. If the Moon is observed with a binocular or a telescope it can be seen many smaller craters and details on the Moon surface. On the Moon surface can be seen the following types of details:

Fig. 14: Different details on the Moon

These details can be observed best with a telescope.

6.Our observations of the Moon
Visual observations
We made a series of observations of the Moon to
learn how to find seas, oceans and larger
craters. The observations were made with a binocular
and with a small school telescope - refractor- with
aperture 6cm.

Our photographical gallery

Fig. 16: Four photos of the Moon made with photographic camera Practica and telescope Celestron, May 2002

Our CCD gallery of the Moon
Images are made with CCD-ST8 on 50/70cm telescope +ST8 in NAO-Rozhen during 2 observational astroschools.

Fig. 17: The Moon exp=0.11sec ................. Fig.18: The Moon exp=0.11sec
date: 16.06. 2002 ........................................... date: 16.06.2002

Fig.19: The Moon exp=1sec ................................... Fig.20: The Moon exp= 1sec
date: 31.07.2002 ...................................................... date: 15.06.2002

7.Comparison of the Moon with the Earth
We especially decided to compare the Moon with the Earth. The comarison was made over one peculiarity of the earth and the Moon that turned out to be the same and for Jupiter's satellite-Jo-the activity of volcanoes. The Earth and the Moon had many active volcanoes millions of years ago. But the Earth's Moon has no large volcanoes. However, vast plains of basaltic lavas cover much of the lunar surface. The earliest astronomers thought, wrongly, that these plains were seas of lunar water. Thus, they were called " mare "(pronounced "mahr-ay"). Mare means "sea" in Latin. In addition, other volcanic features also occur within the lunar mare. The most important are sinuous rilles , dark mantling deposits ,and small volcanic domes and cones. Most of these features are fairly small, however. They form only a tiny fraction of the lunar volcanic record. The activity of volcanoes on the Moon is very different from the Earth's activity.
The settings of mare volcanism reveal another major difference from volcanism on the Earth. Specifically, Earth's volcanoes mostly occur within long linear mountain chains. Mountain chains like the Andes mark the edge of a lithospheric plate. Mountain chains like the Hawaiian Islands mark past plate movements over a mantle hotspot. In contrast, the mare typically occur in the bottoms of very large, very old impact craters. Thus, most of the mare are nearly circular in shape. Further, lunar mountain chains form the edges of these impact basins and tend to surround the lunar mare. There is no evidence that any system of plate tectonics ever developed on the Moon. Finally, the lunar mare are primarily found on one side of the Moon. They cover nearly one third of the lunar nearside, but less than 2% of the lunar farside. The surface is much higher on the farside, however, and the crust is typically much thicker there as well. Thus, the primary factors controlling volcanism on the Moon appear to be surface elevation and crustal thickness.
Finally, there are some major physical differences between volcanism on the Earth and on the Moon. First, lunar gravity is only one sixth that of the Earth's. This means that the forces driving lava flow are weaker on the Moon. Thus, the very flat and smooth mare surfaces imply that mare lavas were very fluid. They could both flow very easily and spread out over large areas. Also, the low gravity means that explosive eruptions can throw debris further on the Moon than on the Earth. Indeed, such eruptions on the Moon should spread lavas out into a broad flat layer and not into the cone-shaped features seen on the Earth. This gives one reason for why large volcanoes are not seen on the Moon. Second, the Moon has essentially no dissolved water. The lunar mare are all bone dry. In contrast, water is one of the most common gases in Earth lavas. Water also plays a major role in driving violent eruptions on the Earth. Thus, the lack of lunar water should strongly affect lunar volcanism. In particular, without water, violent explosive eruptions are much less likely on the Moon. Instead, lavas should just flow smoothly and quietly out onto the surface.

8. Exercises: The Moon surface - two different methods for calculation of the size of craters using photographic and CCD observations
In this exercise we use our own astrophotographes and CCD observations of the Moon.
Exercise 1: Calculation of the size of 3 craters and one bay using a photograph of the Moon.
Task1: Creation of a photograph of the Moon. There are several methods - the easiest
is simply to focus your camera to infinity - and hold or mount it behind the eyepiece of
your telescope. We will use this photograph from Fig21.
Task2: Identify the craters below on a Lunar Map
We identified the following Moon objects: Sinus Iridum (Bay of Rainbows),
Crater Copernicus, Crater Bulliadus
Task3: We will measure the diameter of the Moon and the Moon objects in cm.
We know that the diameter of the Moon is 3,474.8 km. To find the size of a moon
object we used the following dependence:
Diameter object (km ) = (Diameter Moon ( km) x Diameter object (cm )) / Diameter Moon (cm)
The diameter of the Moon from the photograph is 9.2cm
For our objects we calculated the following results:

We will use this exercise to calculate the size of all large objects on the Moon surface. Thus we will make our own Moon map.

Exercise 2: Calculation of the size of objects using CCD images of the Moon
Task1: Creation of a CCD image of the Moon
It could be used a CCD image of the Moon from Internet
We used an image that was made on 16.06.2002 that we made with CCD ST8 and 50/70 cm Schmidt telescope in NAO-Rozhen. The matrix of the CCD camera ST8 is 1530 x 1020 pixels, 13.8 x 9.2 mm.The telescope has focused distance of 1.72m.
Task2: Identify the craters below on a Lunar Map
We identified the following objects: Mare Nectaris, Crater Theophilus, Crater Katerina, Crater Phrakastor, Crater Piccolomini
Task3 : Measurement of the Moon diameter and the diameter of the Moon objects. The image of the Moon on the CCD picture is in pixels. The size of the matrix of the CCD ST8 is 1530x1020pixels and the size is 13.8 x9.2mm. From here we can calculate that one pixel = 0.009mm. We know that the focus distance of the telescope is 172cm and the distance to the Moon is 384 40 km.
We measured the diameter of the objects in pixels and then we converted them into mm. We discussed and determined the geometric connection that allowed us to determine the diameter is the Moon object. The formula that is necessary for calculation of the object's diameter is:
If D object - Diameter of the object (km) , D ccd-object - Diameter of the object from the image (m),
R Moon = Distance to the object(km), F - focus distance of the telescope (m)
Then
D object / R Moon = D ccd-object / F

From here
D object = R Moon x (D ccd-object / F)

Our results:
1. We looked at the image of the Moon 001b-1606.jpg.
It was made in 16.06.2002, in V filter with exposition 0.11sec.

On this image we identified in Mare Nectaris (Sea of Nectar):
1. Crater Theophilus
2. Crater Kiril
3. Crater Katerina
4. Crater Phrakastor
5. Crater Piccolomini
6. Mare Nectaris

 

Scientists can discuss these 2 methods and to compare the accuracy of the calculated data and to look for the place from which the inaccuracy of these methods comes.

The work over these 2 exercises combines receiving images and their working and analysis. When people pass through the different stages: creation of the task, determination of the methods for making the observations, the work over it and its analysis, they will receive new knowledge, will receive new skills and will understand the importance, meaning and how unique is each astronomical observation.

9.Conclusion
The Moon was a very interesting object for us. Humanity has already learned so many things about our satellite and has made many book, articles, web-pages and scientific films. For us it was very difficult to choose what to put in this project. We decided to put this information that can be not easily found on any book or web-page about the Moon. This project was our first step towards the knowledge about the Moon that we will continue enlarging and in future. The Moon is not only the nearest to the Earth space object - the Moon will have an enormous role for the humanity and the far space.

References:
Encyclopedia for children. Moskva Avanta, 1999
http://planetarynames.wr.usgs.gov/append5.html
http://www.pantheon.org/mythica.html
http://www.lpi.usra.edu/lunar_missions_TOC.html
http://www.school-for-champions.com/default.htm

For Contacts:
Team:
Zheni Goranova
Zhaneta Doseva
Leader:
Veselka Radeva- - Astronomical Observatory-Varna, Bulgaria
radevi@mail.varna.techno-link.com
The students are from the Astronomical courses made by the Astronomical Observatory and Planetarium "N.Kopernicus"-Varna

In 1997, Dr. Canup's work received a great deal of publicity by media news sources, some of whom mistakenly thought that the giant impact was a brand new idea. Canup's early work, presented in July 1997, suggested the debris from an impact might not make a moon, but only a swarm of moonlets. Her later work (fall 1997) led to more "success" in aggregating the debris into a single moon.

Fig. 10: The Moon

Fig. 22: TheMoon exp=0.11 sec
date 16.06.2002

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