ABOUT ME 1
MGMP IPA RAYON 3 SMP KABUPATEN MAJALENGKA. SEKRETARIAT DI SMPN 4 MAJA.BY. ARMADA PAHLA, M.Pd
ABOUT ME 2
MGMP IPA RAYON 3 SMP KABUPATEN MAJALENGKA. SEKRETARIAT DI SMPN 4 MAJA.BY. ARMADA PAHLA, M.Pd.
ABOUT ME 3
MGMP IPA RAYON 3 SMP KABUPATEN MAJALENGKA. SEKRETARIAT DI SMPN 4 MAJA.BY. ARMADA PAHLA, M.Pd.
ABOUT ME 4
MGMP IPA RAYON 3 SMP KABUPATEN MAJALENGKA. SEKRETARIAT DI SMPN 4 MAJA.BY. ARMADA PAHLA, M.Pd bersama KADISDIK, KABID DIKDAS, KASI SMP.
ABOUT ME 5
MGMP IPA RAYON 3 SMP KABUPATEN MAJALENGKA. SEKRETARIAT DI SMPN 4 MAJA.BY. ARMADA PAHLA, M.Pd.bersama MKKS, KKPS, dan FORUM MGMP
Sunday 14 April 2013
Sunday 7 April 2013
Thursday 28 March 2013
casey study 1
CASE STUDY
WITH POWER POINT PRESENTATION
I am a science teacher SMPN 1 Cibinong Bogor IX class first semester of academic year 2009/2010, I felt the need to write / make a note after teaching my class wants success in learning
I invite students to learn in an open pavilion with a view of students taught using ICT's in the library media room enough for the number of computers and lap top screen while and infokus I prepare for the presentation.
Biology learning concepts contained in the first half of the lesson plan is a system ekresi / dispensing system in humans is ekresi on Kidney, Liver, Lungs and Skin. I used the approach Cooperatif Learning (CL) techniques using ICT prensentasitasi STAD with power point, but students are not used in prentasi but after I explained and I've coached it turns out students are excited because it is familiar with and accustomed to using power point on the subjects of ICT,
I am learning process begins before the group split into 8 groups of 5 persons in heterogeneous members either gender or level of ability. Each group was given the title for discussion is 2 groups A and C received kidney material, 2 groups E and H can be the heart of matter, the 2 groups B and G can be material lungs and 2 more groups D and F got leather material
In the preliminary process of learning begins with apperception for 10 minutes about the matter before the digestive system with the aim to determine the extent of mastery of the material previously associated with the system ekresi but not all students are ready there are still preparing themselves and Dedi cool talking with friends sebangkunya Fandi, after I give a motivation by asking Smith what is perceived by the skin when hot and overheated answered Dedi Dedi replied afterwards sweat after other students from enthusiastic.
I had a question and answer beginning with the intention of beginning students to gain knowledge in the form of Linda secret of the outcome or results of any ekresi secret of the kidneys, liver, lungs and skin mapu students mentioned most expected answer and then I distribute worksheets in each group to discuss kelaianan secret and disease by 20 minutes and then students prepare for the discussion group
I was walking around observing the group and help the group in the discussion that there are students who ask Dawn pack after discussions continue my activities especially smiled and said to myself it's time to motivate the group of me and I try to answer one of you who can explain my activities especially aimed whole group there Spontaneous group replied that after this presentation describes the results of group discussions forward.
After that time given has been completed and students preparing my presentation gambled groups to perform group presentations, group C draw may turn first appeared, after performing students from group D are Adytya pose questions to the group who performed the C group with kidney material with questions substance whatever in absorption, reabsorsi by the kidneys, the group C is Winda already answered but Adytya not satisfied with the answer. I threw the answers to the other group members, and not far from the answer, the question was finally answered to my satisfaction reinforce and Aditya
Next the group G with presentation material appearing lungs turn asked the group G Sutrisno answered by Rizky but not far from the foregoing that I have to give an answer. I saw the watch live 5 minutes I finally finished making the conclusion of the two materials with other groups spontaneously asked me when I answered giliaran prentasi time runs out and continued on Thursday.
After the bell rang and the students returned to class I asked myself the presentation students were able to absorb the subject matter, but to my disappointment there was not all students are able to absorb the material and my tentative conclusion that students are more empowered to absorb from other sources and open the internet in order to absorb the material more more
Wednesday 27 March 2013
The Implementation of character education
The Implementation of character education implementation in Indonesia in value is still failing to build the nation's dignity and authority.
The rise of the various phenomena of cases of sexual abuse of children of school age and the rise of juvenile delinquency is an indicator that character education failure.
"I think at this time in Indonesia was in a state of" Emergency Moral Good ", said Commissioner X Herlini Amran in the Parliament Complex in Senayan, Jakarta, Tuesday (05/03).
The government still says Herlini, should immediately conduct a comprehensive evaluation related to the implementation of character education or moral content that embodies the national education system.
National Commission for Protection of Child Sexual Assault Case launched against Children in the schools percentage is second only to sexual violence against children in the home. Based on the complaint of child abuse cases in 2012, of 2,637 complaints received, about 60 percent were cases of sexual violence.
In view Herlini glass, moral strengthening of the nation is the ultimate goal of national education. "If fighting is still prevalent subjects, sexual violence among students continues to increase, I think the government has not succeeded in organizing national education," said Herlini.
According to MCC's Women Legislators, the evaluation of the implementation of character education in schools is very useful to ensure the preparation of the implementation of character education in the curriculum of 2013. This includes budgets and strategies related to the strengthening of moral learning students. Implementation of Character Education must also be based on exemplary teachers and involve parents.
In fact, "In 2012 alone, Budget related Character Education Program to reach 100 billion more" he said.
Another thing that needs improvement is the moral aspect merekapasitasi educators themselves, "Output curriculum students scored 2013 is a character, so it is important for all aspects of teacher training by Kemendikbud direkapasitasi immediately before Curriculum 2013 in the run," he added.
Keep in mind, the budget Curriculum 2013 which reached Rp 2.49 trillion, for teacher training budget of Rp 1.09 trillion earmarked 700 thousand more teachers, principals, and supervisors, with 3-5 days training time meetings. Herlini said that the budget for it for the training of teachers should have a clear output.
"Kemendikbud must also assure post Educator Training, they have good moral integrity in school. Do not just competently deliver textbook material, but in his daily behavior is not a good moral example to the student participants, "he said.
Members of the House of Representatives Electoral Riau Islands Region of origin was hoping for this year, "Emergency Moral Good", the new curriculum changes momentum going forward is expected to be a momentum evaluation of character education in Indonesia is still failing to build the nation's values of dignity and authority.
Displays Students Work
Displays Students Work
1. What are the benefits of a display?
• Making classes more interesting
• Children easily get the idea of what is displayed
• The displayed at times been a good example to be followed or imitated by other children.
• Displays motivate children whose work is displayed and also motivate other kids to do the same.
2. What should be displayed?
• The work of children is what will be displayed?
• Writing children like stories, essays, poems, reports, books made by children, models, graphs, pictures, or arts and crafts.
• The work of children who showed no element of creativity and interesting to see and read should be displayed.
• Examples of good kids work for display
• Often children work slow (slow learners) need to be displayed to motivate them
• In addition, anything that can be displayed?
• Pictures, charts, diagrams, and objects that are relevant to the activities being discussed in class.
• Books for kids to read and see
• materials, learning resources, and tools that are being used for learning activities.
3. What should not be displayed?
• Exercise Routine
• The work that is less true or not good for example, such as sloppy, too many errors and / or not done carefully.
4. How to display the children's work?
• Easy to read by children (not too high)
• Work individually to children should be displayed as such can be read easily. Displays should not be mixed with others or not in bundles.
• What should be displayed in a clean, neat, and attractive.
• Objects that are displayed can be attached to the wall, hung from the ceiling, or set on the table to show off.
5. What criteria are used to display the children's work.
• Is it interesting for others to read?
• Do encourage other students to learn from good examples?
• Do encourage people to pay attention?
6. How long / time display to be replaced?
• When it is no longer attractive
• Has become soiled or no longer functions as a source of learning
Note: The display does not need to be specified (labeled) for a particular subject. LIMIT IS NOT NECESSARY FOR TEACHERS
The values in the Nation Character Education and Culture
TThe values in the Nation Character Education and Culture
The values developed in the nation's culture and character education were identified from the following sources.
1. Religion: Indonesian people are religious people. Therefore, the lives of individuals, communities, and nations are always based on religious teachings and beliefs. Politically, any state of life based on values derived from religion. On the basis of these considerations, the values of the culture and character of the nation's education should be based on values and principles derived from religion.
2. Pancasila: the Indonesian unitary state founded on the principles of nationhood and statehood called Pancasila. Pancasila contained in the Preamble of the 1945 Constitution and further elaborated in the articles contained in the 1945 Constitution. That is, the values contained in Pancasila became the values that govern political life, law, economics, society, culture, and art. Culture and national character education aimed at preparing students to be better citizens, ie citizens have the ability, willingness, and implement Pancasila values in his life as a citizen.
3. Culture: as a truth that no human being living in a society that is not based on cultural values recognized that society. Cultural values were used as the basis for giving meaning to the concept and meaning of the communication between the communities. Cultural position of such importance in public life requires a source of cultural values in the nation's culture and character education.
4. National Educational Objectives: the formulation of quality that should be owned by every citizen of Indonesia, developed by various educational units at various levels and pathways. National education goals includes a variety of human values that must be owned by Indonesian citizens. Therefore, the national education goals are the most operational and cultural education in the development of the nation's character
Nation Character Education and Culture
Understanding Nation Character Education and Culture
Law of the Republic of Indonesia Number 20 of 2003 on National Education System (Education Law) defines the functions and objectives of national education to be used in developing educational efforts in Indonesia. Article 3 of the Law on National Education said, "The national education function to develop and form the character and civilization of a dignified nation in the context of the intellectual life of the nation, aimed at developing students' potentials in order to be a man who is faithful and devoted to God Almighty, noble, healthy, knowledgeable , capable, creative, independent, and become citizens of a democratic and accountable ". The national education goals is a formulation of the human qualities that must be developed in Indonesia by each educational unit. Therefore, the formulation of national education goals provide the basis for the development of cultural education and the character of the nation.
To gain insights into the meaning of culture and national character education should be mentioned understanding of the term culture, national character, and education. Understanding presented here is technically advanced and used in developing these guidelines. Teachers of Anthropology, Citizenship Education, and other subjects, which it terms the subject in the relevant subjects, still have complete freedom to discuss and argue about these terms academically.
Culture is defined as the whole system of thought, values, morals, norms, and beliefs (belief) that the resulting human society. Systems thinking, values, morals, norms, and beliefs that are the result of human interaction with each other and their environment. Systems thinking, values, morals, norms and beliefs that are used in human life and produce social systems, economic systems, belief systems, knowledge systems, technology, art, and so forth. Man as a social being into producing systems thinking, values, morals, norms, and beliefs: but also in the interaction with fellow human beings and nature, man is governed by systems thinking, values, morals, norms, and beliefs that have been produced. While human life continues to evolve, it is actually evolving social systems, economic systems, belief systems, science, technology, and art. Education is a deliberate effort to develop the potential of learners, so that they have a system of thinking, values, morals, and beliefs inherited the legacy of the people and develop the appropriate direction for the life of the present and future.
Character is character, character, character, or personality are formed from the internalization of various virtues (virtues) are believed and used as the basis for perspective, think, behave, and act. Virtue consists of a number of values, morals, and values, such as honesty, courage to act, trustworthy, and respectful to others. Interaction with others cultivate one's community character and national character. Therefore, the development of the nation's character can only be done through the development of one's individual character. However, because humans live in social and cultural ligkungan particular, the development of one's individual character can only be done in the social and cultural environment berangkutan. That is, the development of culture and national character can only be done in an educational process that does not release students from the social, cultural, and national culture. Social and cultural environment of the nation is the Pancasila, so the culture and character of the nation's education should be based on the values of Pancasila. In other words, educating the nation's culture and character is developing the values of Pancasila on self-learners through education liver, brain, and physical.
Education is a conscious and systematic effort to develop the potential of learners. Education is also a business community and the nation in preparing young people for the survival of a society and a better nation in the future. Sustainability is characterized by the inheritance of culture and character which has been owned by the community and the nation. Therefore, education is a process of cultural inheritance and national character for the younger generation as well as the development of the culture and character of the nation to improve the quality of life of the people and the nation in the future. In the process of cultural education and the character of the nation, students actively develop her potential, the process of internalization, and appreciation of the values into their personalities to get along in society, to develop a more prosperous society, and to develop the national life of dignity.
On the basis of thought, culture and character development education is very strategic for the nation's survival and excellence in the future. Development should be done through proper planning, appropriate approaches and methods of effective learning and teaching. In keeping with the nature of the values, culture and national character education is a joint effort the school; should therefore be carried out jointly by all teachers and school leaders, through all subjects, and become an integral part of the school culture.
cara menampilkan film sendiri di you tube
Cara upload video ke youtube
bagi yang masih pemula akan bingung jika ingin mengupload video di youtube. Agar anda bisa upload video di youtube maka pertama anda harus daftar menjadi member di youtube (gratis). Setelah mendaftar di youtube anda akan memperoleh akun (account) youtube yang bisa digunakan untuk login (sign in) ke situs youtube agar dapat melakukan upload video.
jika ingin meng-upload video ke youtube maka usahakan ukuran filenya tidak terlalu besar,mengingat koneksi internet di Indonesia yang sangat lambat, sebaiknya ukuran filenya maksimal 30 MB, jika ukurannya lebih besar sebaiknya dipecah menjadi beberapa bagian, atau diturunkan kualitas gambarnya agar ukuran filenya menjadi lebih kecil, dan durasi (lama tayangnya bagusnya sekitar 10 menit).
Prosedur untuk upload file ke youtube adalah sebagai berikut:
1. Buka situs youtube
Di pojok kanan atas klik tombol sign in jika sudah menjadi member dan jika belum jadi member maka sign up yang di klik
(Gambar cewek cantik-nya jangan di klik, nanti tidak login ke akun youtube anda)
Keterangan:
Saya menganggap anda sudah daftar dan sudah punya akun di youtube, jika belum punya akun youtube bisa lihat disini cara buat akun di youtube.
2. Masukkan akun youtube, atau google account (user name dan password)
Kemudian klik Sign in
3. Setelah login ke account youtube anda, maka anda bisa memulai upload video ke youtube.
Di bagian pojok kanan atas halaman, klik Upload
4. Klik Upload video
5. Pilih file di komputer yang akan di upload,
Dalam contoh ini saya menggunakan file video : bersih private data firefox.avi
Klik Open
(File video ini saya buat menggunakan software gratisan Camstudio, yaitu software screen capture video yang bisa merekam kegiatan di layar komputer dan menyimpannya ke format video.)
setelah menunggu unggahan tinggal tambah judul dan deskripsi kemudian save
semoga bermanfaat.... yaaa
2. Masukkan akun youtube, atau google account (user name dan password)
Kemudian klik Sign in
3. Setelah login ke account youtube anda, maka anda bisa memulai upload video ke youtube.
Di bagian pojok kanan atas halaman, klik Upload
4. Klik Upload video
5. Pilih file di komputer yang akan di upload,
Dalam contoh ini saya menggunakan file video : bersih private data firefox.avi
Klik Open
(File video ini saya buat menggunakan software gratisan Camstudio, yaitu software screen capture video yang bisa merekam kegiatan di layar komputer dan menyimpannya ke format video.)
setelah menunggu unggahan tinggal tambah judul dan deskripsi kemudian save
semoga bermanfaat.... yaaa
yel yel anak smp
yel yel motivasi belajardalam waktu 20 detik sangat membantu anak menjadi termotivasi sehingga kekompakan dalam berkelompok menjadi tergugah.... go go anak-anaku
Tuesday 26 March 2013
OPEN CLASS MGMP IPA 3 MAJALENGKA
VIDEO KEGIATAN OPEN CLASS DI SMPN 1 TALAGA MAJALENGKA DENGAN GURU MODEL WIDA SOPWATI,S.Pd PADA KEGIATAN LSBS MGMP IPA RAYON 3 MAJALENGKA. DENGAN OBSERVER DARI PESERTA MGMP IPA SMP RAYON 3 MAJALENGKA.
video pada pembelajaran IPA
video pada pembelajaran IPA di kelas IX SMPN 4 Maja pada pokok bahasan TATA SURYA dengan kelompok belajar yang menfublikasikan yel yel kelompok untuk pemberian motivasi belajar anak
Monday 25 March 2013
info sertifikasi guru
sertifikasi guru merupakan penggiat untuk meningkatkan keprofesionalan guru yang didalam pelaksanaannya sangat sulit untuk mendapat tunjangan tersebut.
contoh di Sukabumi :
SUKABUMI (Pos Kota) – Ratusan guru di Kabupaten Sukabumi, Jawa Barat dinilai tidak layak oleh Kementerian Pendidikan dan Kebudayaan (Kemendikbud).
Mereka tidak lolos sertifikasi penilaian berdasarkan data pokok pendidikan (Dapodik) Kemendikbud pada triwulan pertama. Akibatnya, mereka terancam tidak menerima dana sertifikasi guru.
Berdasarkan data Dinas Pendidikan (Disdik) Kabupaten Sukabumi pada triwulan pertama ada sebanyak 677 guru yang dinyatakan tidak memenuhi syarat. Penetapan hasil ini langsung dilakukan Kemendikbud dengan sejumlah parameter.
Salah satu paremeternya guru dikatakan tidak memenuhi syarat karena tidak mampu mengajar secara tatap muka selama 24 jam seminggu.
Selain itu, guru tersebut mengajar mata pelajaran yang tidak sesuai dengan kompetensinya.
Ketua Tim Teknis Sertifikasi, Dinas Pendidikan (Disdik) Kabupaten Sukabumi, Dede Daniel menjelaskan ratusan guru yang dinilai tidak layak ini masih diberikan kesempatan untuk memperbaiki kinerja.
“Dalam satu tahun para guru diberikan peluang sebanyak empat kali untuk mendapatkan surat keputusan (SK) dana sertifikasi. Sementara pada triwulan pertama ada 4 ribu guru yang dinilai layak mendapatkan tunjangan sertifikasi dengan ketentuan yang ada,” kata Dede, Senin (25/3).
Dede merinci jumlah guru di Kabupaten Sukabumi mencapai sebanyak 12 ribu orang. Guru yang sudah sertifikasi baru mencapai sekitar 7 ribu orang. “Masih ada sekitar 40 persen guru yang belum mendapatkan sertifikasi,” cetusnya.
Di lain sisi, kalangan pendidik mempertanyakan penetapan ratusan guru tidak layak oleh Kemendikbud. Pasalnya, jumlah guru yang dinilai tidak layak cukup banyak. Mereka khawatir adanya kesalahan informasi dalam memasukan data ke Dapodik Kemendikbud.
“Banyak guru yang seharusnya dinyatakan layak malah ditetapkan sebagai guru yang tidak memenuhi syarat. Padahal semua persyaratannya sudah dipenuhi. Jadi kami khawatir adanya kesalahan dalam memasukan data,” keluh salah seorang guru di Kecamatan Gunungguruh
Sunday 24 March 2013
Thursday 21 March 2013
Wednesday 20 March 2013
ALAMAT KEDUTAAN BESAR
Tuesday 19 March 2013
Wednesday 6 March 2013
PEMECAHAN MASALAH FISIKA
Monday 4 March 2013
Lesson Study in SMPN 4 Maja
Friday 22 February 2013
THE STARS AND THE SUN
THE STARS AND THE SUN
DEATH OF THE STARS AND THE SUN8- When the stars are put out. 77-The Emissaries, 8 At the time of the descent of the Quran, people believed that the light of the stars would last forever. This at a time when the inner structure of the stars was a mystery and the fact that the energy of the stars would, one day, be exhausted was not known. The Quran?s prediction about the end of the stars is a miraculous statement. 2- When the planets are scattered. 82-The Shattering, 2 While the verses speak of the putting out of stars, the planets, not light sources, will scatter. The Arabic word for a star is ?najm,? while ?kavkab? is a planet. Given the fact that the planets are dependent on a central star, when this star is no more, the planets will necessarily scatter. (There have been translators who translated both words as stars without heeding the difference between them.) Planets are not light sources, therefore their extinction is out of question. The Quran displays its miraculous attribute in all its statements. 1- When the sun is rolled. 81-The Rolling, 1 The Arabic word ?takwir? refers to the wrapping of the turban around the head in a spiral form; it also means the rolling or winding of a thing into a ball or round mass, or around something. The scene describes how the end of the sun will come. Like all the other stars, our sun also consumes hydrogen atoms by transforming them into helium atoms and releasing energy in the form of radiation, heat and light. The transformation of hydrogen into helium stops with the exhaustion of the hydrogen. Even without the effect of other potential causes, the sun will have to come to an end for this reason. Before their extinction, the stars, according to their sizes, pass through such phases as red giant, white dwarf or black hole. In view of its magnitude, our sun must turn first into a red giant before dying. The sun has been a subject of worship in the history of mankind. People who did not believe in the end of the universe considered the sun itself to be an immortal divinity and thought that the universe and the earth would last eternally; there have been those who believed in the transmigration of souls everlastingly. Having eventually been convinced by scientific discoveries that the world was doomed to die one day, the minds that idolized the sun and the belief in the eternal reincarnation cycle lost their support. The belief in the Hereafter described in the Quran and the end of the universe are interconnected as the stages of a system. Taking cognizance of the fact that the end of the universe will eventually come has reinforced the belief in the Hereafter. 7- And verily the Hour is coming, no doubt about it, and that God will resurrect those who are dead. 22-The Pilgrimage, 7 The description of the end of the universe in the Quran relating to the end of the sun and of the world is given in striking colors. What the people at the Prophet?s time knew about astronomy could not possibly have permitted them to describe such occurrences. Muslims who lived at the time of the revelation of the Quran believed in all these, not because of scientific deductions but because they had faith in the fact that it was easy for God, the Creator of the heavens and the earth, to destroy them. All the statements of the Quran about the disappearance of the stars, the sun and the earth are corroborated today by scientific discoveries. EARTHQUAKES WITH BOILING SEAS 4- When the earth will be shaken up. 56-The Inevitable, 4 When the Hour comes, the entire earth will be shaken by a terrible earthquake. The Quran says that the tremor will cause mountains to be pulverized, and men will run to and fro in panic. As for the sea, we have the following indications: 6- When the seas boil. 81-The Rolling, 6 3- When the seas are suffered to burst forth. 82-The Shattering, 3 An earthquake will pulverize mountains, hot lava will burst forth from many corners of the earth. Volcanoes will erupt and lava will rise from the sea. It is unlikely that the depiction of the end of the world was an exaggeration of natural disasters that Muhammad experienced in his lifetime. The area where Muhammad lived was not on a major earthquake fault-line, and those who spent most of their lives in the middle of desert, most likely, never witnessed the eruption of a volcano in mid-ocean! 5- When the wild beasts are summoned. 81-The Rolling, 5 The Quran draws our attention to the herding together of animals. We know today that animals react to a tremor even before we, as human beings, realize it. For instance, in the zoo in Seattle Woodland, the odd movements of elephants and the restlessness of gorillas in their cages were observed before the earthquake was felt by human beings. This is a domain in which further research studies are being conducted. In view of this statement of the Quran, we think that this research should be intensified. 3- And when the earth is flattened out. 4- And when it throws out whatever it contains and is empty. 84-The Splitting, 3-4 The contents of the earth, the magma, the molten rock, will rise to the surface as lava, as described in the verses quoted. The Quran would like us to turn our attention to the most serious event of earth history to come. Advanced science has demonstrated that the end of the world and the universe is inevitable. No one can assert any longer that the stars and the sun will shine forever, and that the universe and the earth will abide to eternity. 18- Are they waiting until the Hour comes to them suddenly? Its signs have already appeared. How can they benefit then when it has come upon them? 47-Muhammad, 18 Copyright © 2001-2008 Quranic Research Group
astronimy and space
astronimy and space From : A.Armada Pahla Mashad, M.Pd. Solar System “And God of Allah which have created noon and night, moon and sun. Everyone of both that circulate in its orbit..” (LQ:21.33) ‘’And God of Allah have subdued ( pula) for you continuous moon and sun circulate ( in its orbit); and have subdued for you noon and night.’’ (LQ:14.33) INTRODUCTION Solar System the Sun and everything that orbits the Sun, including the nine planets and their satellites; the asteroids and comets; and interplanetary dust and gas. The term may also refer to a group of celestial bodies orbiting another star (see Extrasolar Planets). In this article, solar system refers to the system that includes Earth and the Sun. The dimensions of the solar system are specified in terms of the mean distance from Earth to the Sun, called the astronomical unit (AU). One AU is 150 million km (about 93 million mi). The most distant known planet, Pluto, orbits about 39 AU from the Sun. Estimates for the boundary where the Sun’s magnetic field ends and interstellar space begins—called the heliopause—range from 86 to 100 AU. The most distant known planetoid orbiting the Sun is Sedna, whose discovery was reported in March 2004. A planetoid is an object that is too small to be a planet. At the farthest point in its orbit, Sedna is about 900 AU from the Sun. Comets known as long-period comets, however, achieve the greatest distance from the Sun; they have highly eccentric orbits ranging out to 50,000 AU or more. The solar system was the only planetary system known to exist around a star similar to the Sun until 1995, when astronomers discovered a planet about 0.6 times the mass of Jupiter orbiting the star 51 Pegasi. Jupiter is the most massive planet in our solar system. Soon after, astronomers found a planet about 8.1 times the mass of Jupiter orbiting the star 70 Virginis, and a planet about 3.5 times the mass of Jupiter orbiting the star 47 Ursa Majoris. Since then, astronomers have found planets and disks of dust in the process of forming planets around many other stars. Most astronomers think it likely that solar systems of some sort are numerous throughout the universe. See Astronomy; Galaxy; Star. THE SUN AND THE SOLAR WIND The Sun is a typical star of intermediate size and luminosity. Sunlight and other radiation are produced by the conversion of hydrogen into helium in the Sun’s hot, dense interior (see Nuclear Energy). Although this nuclear fusion is transforming 600 million metric tons of hydrogen each second, the Sun is so massive (2 × 1030 kg, or 4.4 × 1030 lb) that it can continue to shine at its present brightness for 6 billion years. This stability has allowed life to develop and survive on Earth. For all the Sun’s steadiness, it is an extremely active star. On its surface, dark sunspots bounded by intense magnetic fields come and go in 11-year cycles and sudden bursts of charged particles from solar flares can cause auroras and disturb radio signals on Earth. A continuous stream of protons, electrons, and ions also leaves the Sun and moves out through the solar system. This solar wind shapes the ion tails of comets and leaves its traces in the lunar soil, samples of which were brought back from the Moon’s surface by piloted United States Apollo spacecraft (see Space Exploration; Apollo program). The Sun’s activity also influences the heliopause, a region of space that astronomers believe marks the boundary between the solar system and interstellar space. The heliopause is a dynamic region that expands and contracts due to the constantly changing speed and pressure of the solar wind. In November 2003 a team of astronomers reported that the Voyager 1 spacecraft appeared to have encountered the outskirts of the heliopause at about 86 AU from the Sun. They based their report on data that indicated the solar wind had slowed from 1.1 million km/h (700,000 mph) to 160,000 km/h (100,000 mph). This finding is consistent with the theory that when the solar wind meets interstellar space at a turbulent zone known as the termination shock boundary, it will slow abruptly. However, another team of astronomers disputed the finding, saying that the spacecraft had neared but had not yet reached the heliopause. THE MAJOR PLANETS Nine major planets are currently known. They are commonly divided into two groups: the inner planets (Mercury, Venus, Earth, and Mars) and the outer planets (Jupiter, Saturn, Uranus, and Neptune). The inner planets are small and are composed primarily of rock and iron. The outer planets are much larger and consist mainly of hydrogen, helium, and ice. Pluto does not belong to either group, and there is an ongoing debate as to whether Pluto should be categorized as a major planet. Mercury is surprisingly dense, apparently because it has an unusually large iron core. With only a transient atmosphere, Mercury has a surface that still bears the record of bombardment by asteroidal bodies early in its history. Venus has a carbon dioxide atmosphere 90 times thicker than that of Earth, causing an efficient greenhouse effect by which the Venusian atmosphere is heated. The resulting surface temperature is the hottest of any planet—about 477°C (about 890°F). Earth is the only planet known to have abundant liquid water and life. However, in 2004 astronomers with the National Aeronautics and Space Administration’s Mars Exploration Rover mission confirmed that Mars once had liquid water on its surface. Scientists had previously concluded that liquid water once existed on Mars due to the numerous surface features on the planet that resemble water erosion found on Earth. Mars’s carbon dioxide atmosphere is now so thin that the planet is dry and cold, with polar caps of frozen water and solid carbon dioxide, or dry ice. However, small jets of subcrustal water may still erupt on the surface in some places. Jupiter is the largest of the planets. Its hydrogen and helium atmosphere contains pastel-colored clouds, and its immense magnetosphere, rings, and satellites make it a planetary system unto itself. One of Jupiter’s largest moons, Io, has volcanoes that produce the hottest surface temperatures in the solar system. At least four of Jupiter’s moons have atmospheres, and at least three show evidence that they contain liquid or partially frozen water. Jupiter’s moon Europa may have a global ocean of liquid water beneath its icy crust. Saturn rivals Jupiter, with a much more intricate ring structure and a similar number of satellites. One of Saturn’s moons, Titan, has an atmosphere thicker than that of any other satellite in the solar system. Uranus and Neptune are deficient in hydrogen compared with Jupiter and Saturn; Uranus, also ringed, has the distinction of rotating at 98° to the plane of its orbit. Pluto seems similar to the larger, icy satellites of Jupiter or Saturn. Pluto is so distant from the Sun and so cold that methane freezes on its surface. See also Planetary Science. OTHER ORBITING BODIES The asteroids are small rocky bodies that move in orbits primarily between the orbits of Mars and Jupiter. Numbering in the thousands, asteroids range in size from Ceres, which has a diameter of 1,003 km (623 mi), to microscopic grains. Some asteroids are perturbed, or pulled by forces other than their attraction to the Sun, into eccentric orbits that can bring them closer to the Sun. If the orbits of such bodies intersect that of Earth, they are called meteoroids. When they appear in the night sky as streaks of light, they are known as meteors, and recovered fragments are termed meteorites. Laboratory studies of meteorites have revealed much information about primitive conditions in our solar system. The surfaces of Mercury, Mars, and several satellites of the planets (including Earth’s Moon) show the effects of an intense bombardment by asteroidal objects early in the history of the solar system. On Earth that record has eroded away, except for a few recently found impact craters. Some meteors and interplanetary dust may also come from comets, which are basically aggregates of dust and frozen gases typically 5 to 10 km (about 3 to 6 mi) in diameter. Comets orbit the Sun at distances so great that they can be perturbed by stars into orbits that bring them into the inner solar system. As comets approach the Sun, they release their dust and gases to form a spectacular coma and tail. Under the influence of Jupiter’s strong gravitational field, comets can sometimes adopt much smaller orbits. The most famous of these is Halley’s Comet, which returns to the inner solar system at 75-year periods. Its most recent return was in 1986. In July 1994 fragments of Comet Shoemaker-Levy 9 bombarded Jupiter’s dense atmosphere at speeds of about 210,000 km/h (130,000 mph). Upon impact, the tremendous kinetic energy of the fragments was released through massive explosions, some resulting in fireballs larger than Earth. Comets circle the Sun in two main groups, within the Kuiper Belt or within the Oort cloud. The Kuiper Belt is a ring of debris that orbits the Sun beyond the planet Neptune. Many of the comets with periods of less than 500 years come from the Kuiper Belt. In 2002 astronomers discovered a planetoid in the Kuiper Belt, and they named it Quaoar. The Oort cloud is a hypothetical region about halfway between the Sun and the heliopause. Astronomers believe that the existence of the Oort cloud, named for Dutch astronomer Jan Oort, explains why some comets have very long periods. A chunk of dust and ice may stay in the Oort cloud for thousands of years. Nearby stars sometimes pass close enough to the solar system to push an object in the Oort cloud into an orbit that takes it close to the Sun. The first detection of the long-hypothesized Oort cloud came in March 2004 when astronomers reported the discovery of a planetoid about 1,700 km (about 1,000 mi) in diameter. They named it Sedna, after a sea goddess in Inuit mythology. Sedna was found about 13 billion km (about 8 billion mi) from the Sun. At its farthest point from the Sun, Sedna is the most distant object in the solar system and is about 130 billion km (about 84 billion mi) from the Sun. Many of the objects that do not fall into the asteroid belts, the Kuiper Belt, or the Oort cloud may be comets that will never make it back to the Sun. The surfaces of the icy satellites of the outer planets are scarred by impacts from such bodies. The asteroid-like object Chiron, with an orbit between Saturn and Uranus, may itself be an extremely large inactive comet. Similarly, some of the asteroids that cross the path of Earth’s orbit may be the rocky remains of burned-out comets. Chiron and similar objects called the Centaurs probably escaped from the Kuiper Belt and were drawn into their irregular orbits by the gravitational pull of the giant outer planets, Jupiter, Saturn, Neptune, and Uranus. The Sun was also found to be encircled by rings of interplanetary dust. One of them, between Jupiter and Mars, has long been known as the cause of zodiacal light, a faint glow that appears in the east before dawn and in the west after dusk. Another ring, lying only two solar widths away from the Sun, was discovered in 1983. MOVEMENTS OF THE PLANETS AND THEIR SATELLITES If one could look down on the solar system from far above the North Pole of Earth, the planets would appear to move around the Sun in a counterclockwise direction. All of the planets except Venus and Uranus rotate on their axes in this same direction. The entire system is remarkably flat—only Mercury and Pluto have obviously inclined orbits. Pluto’s orbit is so elliptical that it is sometimes closer than Neptune to the Sun. The satellite systems mimic the behavior of their parent planets and move in a counterclockwise direction, but many exceptions are found. Jupiter, Saturn, and Neptune each have at least one satellite that moves around the planet in a retrograde orbit (clockwise instead of counterclockwise), and several satellite orbits are highly elliptical. Jupiter, moreover, has trapped two clusters of asteroids (the so-called Trojan asteroids) leading and following the planet by 60° in its orbit around the Sun. (Some satellites of Saturn have done the same with smaller bodies.) The comets exhibit a roughly spherical distribution of orbits around the Sun. Within this maze of motions, some remarkable patterns exist: Mercury rotates on its axis three times for every two revolutions about the Sun; no asteroids exist with periods (intervals of time needed to complete one revolution) 1/2, 1/3, …, 1/n (where n is an integer) the period of Jupiter; the three inner Galilean satellites of Jupiter have periods in the ratio 4:2:1. These and other examples demonstrate the subtle balance of forces that is established in a gravitational system composed of many bodies. THEORIES OF ORIGIN Despite their differences, the members of the solar system probably form a common family. They seem to have originated at the same time; few indications exist of bodies joining the solar system, captured later from other stars or interstellar space. Early attempts to explain the origin of this system include the nebular hypothesis of the German philosopher Immanuel Kant and the French astronomer and mathematician Pierre Simon de Laplace, according to which a cloud of gas broke into rings that condensed to form planets. Doubts about the stability of such rings led some scientists to consider various catastrophic hypotheses, such as a close encounter of the Sun with another star. Such encounters are extremely rare, and the hot, tidally disrupted gases would dissipate rather than condense to form planets. Current theories connect the formation of the solar system with the formation of the Sun itself, about 4.7 billion years ago. The fragmentation and gravitational collapse of an interstellar cloud of gas and dust, triggered perhaps by nearby supernova explosions, may have led to the formation of a primordial solar nebula. The Sun would then form in the densest, central region. It is so hot close to the Sun that even silicates, which are relatively dense, have difficulty forming there. This phenomenon may account for the presence near the Sun of a planet such as Mercury, having a relatively small silicate crust and a larger than usual, dense iron core. (It is easier for iron dust and vapor to coalesce near the central region of a solar nebula than it is for lighter silicates to do so.) At larger distances from the center of the solar nebula, gases condense into solids such as are found today from Jupiter outward. Evidence of a possible preformation supernova explosion appears as traces of anomalous isotopes in tiny inclusions in some meteorites. This association of planet formation with star formation suggests that billions of other stars in our galaxy may also have planets. The high frequency of binary and multiple stars, as well as the large satellite systems around Jupiter and Saturn, attest to the tendency of collapsing gas clouds to fragment into multibody systems. See separate articles for most of the celestial bodies mentioned in this article. See also Exobiology. Contributed By:Tobias C. Owen Microsoft ® Encarta ® 2006. © 1993-2005 Microsoft Corporation. All rights reserved.
