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Human factors and ergonomics

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Human factors and Ergonomics (HF&E) is a multidisciplinary field incorporating contributions from psychology, engineering, industrial design, graphic design, statistics, operations research and anthropometry. In essence it is the study of designing equipment and devices that fit the human body and its cognitive abilities. The two terms "human factors" and "ergonomics" are essentially synonymous.^[1][2]
The International Ergonomics Association defines ergonomics or human factors as follows:^[2]

Ergonomics (or human factors) is the scientific discipline concerned with the understanding of interactions among humans and other elements of a system, and the profession that applies theory, principles, data and methods to design in order to optimize human well-being and overall system performance.

HF&E is employed to fulfill the goals of health and safety and productivity. It is relevant in the design of such things as safe furniture and easy-to-use interfaces to machines and equipment. Proper ergonomic design is necessary to prevent repetitive strain injuries and other musculoskeletal disorders, which can develop over time and can lead to long-term disability.
Human factors and ergonomics is concerned with the ‘fit’ between the user, equipment and their environments. It takes account of the user's capabilities and limitations in seeking to ensure that tasks, functions, information and the environment suit each user.
To assess the fit between a person and the used technology, human factors specialists or ergonomists consider the job (activity) being done and the demands on the user; the equipment used (its size, shape, and how appropriate it is for the task), and the information used (how it is presented, accessed, and changed). Ergonomics draws on many disciplines in its study of humans and their environments, including anthropometry, biomechanics, mechanical engineering, industrial engineering, industrial design, information design, kinesiology, physiology and psychology.

Contents  [hide]  1 Etymology 2 History of the field 3 HF&E Organisations 3.1 Related organizations 4 Specialisations 5 Applications 6 Practitioners 7 Methods 7.1 Weaknesses of HF&E Methods 8 See also 9 References 10 Further reading 11 External links

[edit] Etymology

Ergonomics: the science of designing user interaction with equipment and workplaces to fit the user.

The term ergonomics, from Greek Έργον, meaning "work", and Νόμος, meaning "natural laws", first entered the modern lexicon when Wojciech Jastrzębowski used the word in his 1857 article Rys ergonomji czyli nauki o pracy, opartej na prawdach poczerpniętych z Nauki Przyrody (The Outline of Ergonomics, i.e. Science of Work, Based on the Truths Taken from the Natural Science).^[3] The introduction of the term to the English lexicon is widely attributed to British psychologist Hywel Murrell, at the 1949 meeting at the UK's Admiralty, which led to the foundation of The Ergonomics Society. He used it to encompass the studies in which he had been engaged during and after the World War II.^[4]
The expression human factors is a North American term which has been adopted to emphasise the application of the same methods to non work-related situations. A "human factor" is a physical or cognitive property of an individual or social behavior specific to humans that may influence the functioning of technological systems. The terms "human factors" and "ergonomics" are essentially synonymous.^[1]

[edit] History of the field

The foundations of the science of ergonomics appear to have been laid within the context of the culture of Ancient Greece. A good deal of evidence indicates that Greek civilization in the 5th century BC used ergonomic principles in the design of their tools, jobs, and workplaces. One outstanding example of this can be found in the description Hippocrates gave of how a surgeon's workplace should be designed and how the tools he uses should be arranged.^[5] The archaeological record also shows that the early Egyptian dynasties made tools and household equipment that illustrated ergonomic principles. It is therefore questionable whether the claim by Marmaras, et al., regarding the origin of ergonomics, can be justified.^[6]
In the 19th century, Frederick Winslow Taylor pioneered the "scientific management" method, which proposed a way to find the optimum method of carrying out a given task. Taylor found that he could, for example, triple the amount of coal that workers were shoveling by incrementally reducing the size and weight of coal shovels until the fastest shoveling rate was reached.^[7] Frank and Lillian Gilbreth expanded Taylor's methods in the early 1900s to develop the "time and motion study". They aimed to improve efficiency by eliminating unnecessary steps and actions. By applying this approach, the Gilbreths reduced the number of motions in bricklaying from 18 to 4.5, allowing bricklayers to increase their productivity from 120 to 350 bricks per hour.^[7]
Previous to World War I the focus of aviation psychology was on the aviator himself, but the war shifted the focus onto the aircraft, in particular, the design of controls and displays, the effects of altitude and environmental factors on the pilot. The war saw the emergence of aeromedical research and the need for testing and measurement methods. Studies on driver behaviour started gaining momentum during this period, as Henry Ford started providing millions of Americans with automobiles. Another major development during this period was the performance of aeromedical research. By the end of WWI, two aeronautical labs were established, one at Brooks Airforce Base, Texas and the other at Wright field outside of Dayton, Ohio. Many tests were conducted to determine which characteristic differentiated the successful pilots from the unsuccessful ones. During the early 1930s, Edwin Link developed the first flight simulator. The trend continued and more sophisticated simulators and test equipment were developed. Another significant development was in the civilian sector, where the effects of illumination on worker productivity were examined. This led to the identification of the Hawthorne Effect, which suggested that motivational factors could significantly influence human performance.^[7]
World War II marked the development of new and complex machines and weaponry, and these made new demands on operators' cognition. it was no longer possible to adopt the Tayloristic principle of matching individuals to preexisting jobs. Now the design of equipment had to take into account human limitations and take advantage of human capabilities. The decision-making, attention, situational awareness and hand-eye coordination of the machine's operator became key in the success or failure of a task. There was a lot of research conducted to determine the human capabilities and limitations that had to be accomplished. A lot of this research took off where the aeromedical research between the wars had left off. An example of this is the study done by Fitts and Jones (1947), who studied the most effective configuration of control knobs to be used in aircraft cockpits. A lot of this research transcended into other equipment with the aim of making the controls and displays easier for the operators to use. The entry of the terms "human factors" and "ergonomics" into the modern lexicon date from this period. It was observed that fully functional aircraft, flown by the best-trained pilots, still crashed. In 1943, Alphonse Chapanis, a lieutenant in the U.S. Army, showed that this so-called "pilot error" could be greatly reduced when more logical and differentiable controls replaced confusing designs in airplane cockpits. After the war, the Army Air Force published 19 volumes summarizing what had been established from research during the war.^[7]
In the decades since WWII, HF&E has continued to flourish and diversify. Work by Elias Porter and others within the RAND Corporation after WWII extended the conception of HF&E. "As the thinking progressed, a new concept developed - that it was possible to view an organization such as an air-defense, man-machine system as a single organism and that it was possible to study the behavior of such an organism. It was the climate for a breakthrough."^[8] In the initial 20 years after the WWII, most activities were done by the "founding fathers": Alphonse Chapanis, Paul Fitts, and Small.^{[citation needed]}
The beginning of The Cold War led to a major expansion of Defense supported research laboratories. Also, a lot of labs established during WWII started expanding. Most of the research following the war was military-sponsored. Large sums of money were granted to universities to conduct research. The scope of the research also broadened from small equipments to entire workstations and systems. Concurrently, a lot of opportunities started opening up in the civilian industry. The focus shifted from research to participation through advice to engineers in the design of equipment. After 1965, the period saw a maturation of the discipline. The field has expanded with the development of the computer and computer applications.^[7]
The Space Age created new human factors issues such as weightlessness and extreme g-forces. Tolerance of the harsh environment of space and it's effects on the mind and body were widely studied^{[citation needed]}
The dawn of the Information Age has resulted in the related field of Human–computer interaction (HCI). Likewise, the growing demand for and competition among consumer goods and electronics has resulted in more companies including human factors in product design.

[edit] HF&E Organisations

Formed in 1946 in the UK, the oldest professional body for human factors specialists and ergonomists is The Institute of Ergonomics and Human Factors, formally known as The Ergonomics Society.
The Human Factors and Ergonomics Society (HFES) was founded in 1957. The Society's mission is to promote the discovery and exchange of knowledge concerning the characteristics of human beings that are applicable to the design of systems and devices of all kinds.
The International Ergonomics Association (IEA) is a federation of ergonomics and human factors societies from around the world. The mission of the IEA is to elaborate and advance ergonomics science and practice, and to improve the quality of life by expanding its scope of application and contribution to society. As of September 2008, the International Ergonomics Association has 46 federated societies and 2 affiliated societies.

[edit] Related organizations

The Institute of Occupational Medicine (IOM) was founded by the coal industry in 1969, from the outset the IOM employed ergonomics staff to apply ergonomics principles to the design of mining machinery and environments. To this day, the IOM continues ergonomics activities, especially in the fields of musculoskeletal disorders; heat stress and the ergonomics of personal protective equipment (PPE). Like many in occupational ergonomics, the demands and requirements of an ageing UK workforce are a growing concern and interest to IOM ergonomists.
The International Society of Automotive Engineers (SAE) is a professional organization for mobility engineering professionals in the aerospace, automotive, and commercial vehicle industries. The Society is a standards development organization for the engineering of powered vehicles of all kinds, including cars, trucks, boats, aircraft, and others. The Society of Automotive Engineers has established a number of standards used in the automotive industry and elsewhere. It encourages the design of vehicles in accordance with established Human Factors principles. It is one the most influential organizations with respect to Ergonomics work in Automotive design. This society regularly holds conferences which address topics spanning all aspects of Human Factors/Ergonomics.^{[citation needed]}

[edit] Specialisations

Specialisations within this field include visual ergonomics, cognitive ergonomics, usability, human–computer interaction, and user experience engineering. New terms are being generated all the time. For instance, “user trial engineer” may refer to a human factors professional who specialises in user trials.^{[citation needed]} Although the names change, human factors professionals apply an understanding of human factors to the design of equipment, systems and working methods in order to improve comfort, health, safety and productivity.
According to the International Ergonomics Association within the discipline of ergonomics there exist domains of specialization:

• Physical ergonomics is concerned with human anatomy, and some of the anthropometric, physiological and bio mechanical characteristics as they relate to physical activity.^[2]
• Cognitive ergonomics is concerned with mental processes, such as perception, memory, reasoning, and motor response, as they affect interactions among humans and other elements of a system. (Relevant topics include mental workload, decision-making, skilled performance, human-computer interaction, human reliability, work stress and training as these may relate to human-system and Human-Computer Interaction design.)^[2]
• Organizational ergonomics is concerned with the optimization of socio-technical systems, including their organizational structures, policies, and processes.(Relevant topics include communication, crew resource management, work design, design of working times, teamwork, participatory design, community ergonomics, cooperative work, new work programs, virtual organizations, telework, and quality management.)^[2]
• Environmental ergonomics is concerned with human interaction with the environment. The physical environment is characterized by: climate, temperature, pressure, vibration, light.^[9]

There are more than twenty technical subgroups within the Human Factors and Ergonomics Society^[10] (HFES), which indicates the range of applications for ergonomics.

[edit] Applications

Human factors issues arise in simple systems and consumer products as well. Some examples include cellular telephones and other hand held devices that continue to shrink yet grow more complex (a phenomenon referred to as "creeping featurism"), millions of VCRs blinking "12:00" across the world because very few people can figure out how to program them, or alarm clocks that allow sleepy users to inadvertently turn off the alarm when they mean to hit 'snooze'. A user-centered design (UCD), also known as a systems approach or the usability engineering life cycle aims to improve the user-system. Ergonomic principles have been widely used in the design of both consumer and industrial products. Past examples include screwdriver handles made with serrations to improve finger grip, and use of soft thermoplastic elastomers to increase friction between the skin of the hand and the handle surface.^{[citation needed]}
HF&E continues to be successfully applied in the fields of aerospace, aging, health care, IT, product design, transportation, training, nuclear and virtual environments, among others. Physical ergonomics is important in the medical field, particularly to those diagnosed with physiological ailments or disorders such as arthritis (both chronic and temporary) or carpal tunnel syndrome. Pressure that is insignificant or imperceptible to those unaffected by these disorders may be very painful, or render a device unusable, for those who are. Many ergonomically designed products are also used or recommended to treat or prevent such disorders, and to treat pressure-related chronic pain.^{[citation needed]}
One of the most prevalent types of work-related injuries are musculoskeletal disorders. Work-related musculoskeletal disorders (WRMDs) result in persistent pain, loss of functional capacity and work disability, but their initial diagnosis is difficult because they are mainly based on complaints of pain and other symptoms.^[11] Every year 1.8 million U.S. workers experience WRMDs and nearly 600,000 of the injuries are serious enough to cause workers to miss work.^[12] Certain jobs or work conditions cause a higher rate worker complaints of undue strain, localized fatigue, discomfort, or pain that does not go away after overnight rest. These types of jobs are often those involving activities such as repetitive and forceful exertions; frequent, heavy, or overhead lifts; awkward work positions; or use of vibrating equipment.^[13] The Occupational Safety and Health Administration (OSHA) has found substantial evidence that ergonomics programs can cut workers' compensation costs, increase productivity and decrease employee turnover.^[14] Therefore, it is important to gather data to identify jobs or work conditions that are most problematic, using sources such as injury and illness logs, medical records, and job analyses.^[13]
The emerging field of human factors in highway safety uses human factor principles to understand the actions and capabilities of road users - car and truck drivers, pedestrians, bicyclists, etc. - and use this knowledge to design roads and streets to reduce traffic collisions. Driver error is listed as a contributing factor in 44% of fatal collisions in the United States, so a topic of particular interest is how road users gather and process information about the road and its environment, and how to assist them to make the appropriate decision. ^[15]

[edit] Practitioners

Human factors practitioners come from a variety of backgrounds, though predominantly they are psychologists (from the various subfields of engineering psychology, cognitive psychology, perceptual psychology, applied psychology and experimental psychology) and physiologists. Designers (industrial, interaction, and graphic), anthropologists, technical communication scholars and computer scientists also contribute. Typically, an ergonomist will have an undergraduate degree in psychology, engineering, design or health sciences, and usually a masters degree or doctoral degree in a related discipline. Though some practitioners enter the field of human factors from other disciplines, both M.S. and Ph.D. degrees in Human Factors Engineering are available from several universities worldwide. The Human Factors Research Group (HFRG) at the University of Nottingham provides human factors courses at both at MSc and PhD level including a distance learning course in Applied Ergonomics.^[16] Other Universities to offer postgraduate courses in human factors in the UK include Loughborough University, Cranfield University and the University of Oxford.^{[citation needed]}

[edit] Methods

Until recently, methods used to evaluate human factors and ergonomics ranged from simple questionnaires to more complex and expensive usability labs.^[17] Some of the more common HF&E methods are listed below:

• Ethnographic analysis: Using methods derived from ethnography, this process focuses on observing the uses of technology in a practical environment. It is a qualitative and observational method that focuses on "real-world" experience and pressures, and the usage of technology or environments in the workplace. The process is best used early in the design process.^[18]

• Focus Groups are another form of qualitative research in which one individual will facilitate discussion and elicit opinions about the technology or process under investigation. This can be on a one to one interview basis, or in a group session. Can be used to gain a large quantity of deep qualitative data,^[19] though due to the small sample size, can be subject to a higher degree of individual bias.^[20] Can be used at any point in the design process, as it is largely dependent on the exact questions to be pursued, and the structure of the group. Can be extremely costly.

• Iterative design: Also known as prototyping, the iterative design process seeks to involve users at several stages of design, in order to correct problems as they emerge. As prototypes emerge from the design process, these are subjected to other forms of analysis as outlined in this article, and the results are then taken and incorporated into the new design. Trends amongst users are analyzed, and products redesigned. This can become a costly process, and needs to be done as soon as possible in the design process before designs become too concrete.^[18]

• Meta-analysis: A supplementary technique used to examine a wide body of already existing data or literature in order to derive trends or form hypotheses in order to aid design decisions. As part of a literature survey, a meta-analysis can be performed in order to discern a collective trend from individual variables.^[20]

• Subjects-in-tandem: Two subjects are asked to work concurrently on a series of tasks while vocalizing their analytical observations. This is observed by the researcher, and can be used to discover usability difficulties. This process is usually recorded.^{[citation needed]}

• Surveys and Questionnaires: A commonly used technique outside of Human Factors as well, surveys and questionnaires have an advantage in that they can be administered to a large group of people for relatively low cost, enabling the researcher to gain a large amount of data. The validity of the data obtained is, however, always in question, as the questions must be written and interpreted correctly, and are, by definition, subjective. Those who actually respond are in effect self-selecting as well, widening the gap between the sample and the population further.^[20]

• Task analysis: A process with roots in activity theory, task analysis is a way of systematically describing human interaction with a system or process to understand how to match the demands of the system or process to human capabilities. The complexity of this process is generally proportional to the complexity of the task being analyzed, and so can vary in cost and time involvement. It is a qualitative and observational process. Best used early in the design process.^[20]

• Think aloud protocol: Also known as "concurrent verbal protocol", this is the process of asking a user to execute a series of tasks or use technology, while continuously verbalizing their thoughts so that a researcher can gain insights as to the users' analytical process. Can be useful for finding design flaws that do not affect task performance, but may have a negative cognitive affect on the user. Also useful for utilizing experts in order to better understand procedural knowledge of the task in question. Less expensive than focus groups, but tends to be more specific and subjective.^[21]

• User analysis: This process is based around designing for the attributes of the intended user or operator, establishing the characteristics that define them, creating a persona for the user. Best done at the outset of the design process, a user analysis will attempt to predict the most common users, and the characteristics that they would be assumed to have in common. This can be problematic if the design concept does not match the actual user, or if the identified are too vague to make clear design decisions from. This process is, however, usually quite inexpensive, and commonly used.^[20]

• "Wizard of Oz": This is a comparatively uncommon technique but has seen some use in mobile devices. Based upon the Wizard of Oz experiment, this technique involves an operator who remotely controls the operation of a device in order to imitate the response of an actual computer program. It has the advantage of producing a highly changeable set of reactions, but can be quite costly and difficult to undertake.

• Methods Analysis is the process of studying the tasks a worker completes using a step-by-step investigation. Each task in broken down into smaller steps until each motion the worker performs is described. Doing so enables you to see exactly where repetitive or straining tasks occur.

• Time studies determine the time required for a worker to complete each task. Time studies are often used to analyze cyclical jobs. They are considered “event based” studies because time measurements are triggered by the occurrence of predetermined events.^[22]

• Work sampling is a method in which the job is sampled at random intervals to determine the proportion of total time spent on a particular task.^[22] It provides insight into how often workers are performing tasks which might cause strain on their bodies.

• Predetermined time systems are methods for analyzing the time spent by workers on a particular task. One of the most widely used predetermined time system is called Methods-Time-Measurement or MTM. Other common work measurement systems include MODAPTS and MOST.^{[citation needed]}

• Cognitive Walkthrough: This method is a usability inspection method in which the evaluators can apply user perspective to task scenarios to identify design problems. As applied to macroergonomics, evaluators are able to analyze the usability of work system designs to identify how well a work system is organized and how well the workflow is integrated.^[23]

• Kansei Method: This is a method that transforms consumer’s responses to new products into design specifications. As applied to macroergonomics, this method can translate employee’s responses to changes to a work system into design specifications.^[23]

• High Integration of Technology, Organization, and People (HITOP): This is a manual procedure done step-by-step to apply technological change to the workplace. It allows managers to be more aware of the human and organizational aspects of their technology plans, allowing them to efficiently integrate technology in these contexts.^[23]

• Top Modeler: This model helps manufacturing companies identify the organizational changes needed when new technologies are being considered for their process.^[23]

• Computer-integrated Manufacturing, Organization, and People System Design (CIMOP): This model allows for evaluating computer-integrated manufacturing, organization, and people system design based on knowledge of the system.^[23]

• Anthropotechnology: This method considers analysis and design modification of systems for the efficient transfer of technology from one culture to another.^[23]

• Systems Analysis Tool (SAT): This is a method to conduct systematic trade-off evaluations of work-system intervention alternatives.^[23]

• Macroergonomic Analysis of Structure (MAS): This method analyzes the structure of work systems according to their compatibility with unique sociotechnical aspects.^[23]

• Macroergonomic Analysis and Design (MEAD): This method assesses work-system processes by using a ten-step process.^[23]

• Virtual Manufacturing and Response Surface Methodology (VMRSM): This method uses computerized tools and statistical analysis for workstation design.^[24]

[edit] Weaknesses of HF&E Methods

Problems in how usability measures are employed include the fact that measures of learning and retention of how to use an interface are rarely employed during methods and some studies treat measures of how users interact with interfaces as synonymous with quality-in-use, despite an unclear relation.^[25]
Although field methods can be extremely useful because they are conducted in the users natural environment, they have some major limitations to consider. The limitations include:

1. Usually take more time and resources than other methods
2. Very high effort in planning, recruiting, and executing than other methods
3. Much longer study periods and therefore requires much goodwill among the participants
4. Studies are longitudinal in nature, therefore, attrition can become a problem

Jawaban Mengapa Pluto Tidak dianggap Planet

Pluto pertama kali ditemukan pada tahun 1930 oleh Clyde W. Tombaugh. Nama Pluto juga merupakan nama seorang dewa dari kebudayaan Romawi yang menguasai dunia kematian (Hades dalam kebudayaan Yunani).

Orbit Pluto yang berbentuk elips tumpang tindih dengan orbit Neptunus. Orbitnya terhadap Matahari juga terlalu melengkung dibandingkan delapan objek yang diklasifikasikan sebagai planet. Pluto juga berukuran amat kecil, bahkan lebih kecil dari Bulan, sehingga terlalu kecil untuk disebut planet.

Ada 3 kriteria utama dari sebuah planet yaitu :

1. Planet harus memilki orbit mengelilingi matahari,

2. Planet harus memiliki massa yang cukup besar sehingga memiliki bentuk kurang lebih bulat seperti bola,

3. Dan planet harus mampu menyapu objek-objek yang berada di lintasan orbitnya.

Pada kriteria ke-2 ukuran Pluto bisa dikatakan terlalu kecil. Massa Pluto adalah sepertujuh dari massa bulan kita, dengan diameter 2300 km, dua per tiga dari diameter bulan (3476 km).

Sedangkan pada kriteria ke-3 beberapa objek ditemukan di sekitar lintasannya. Lintasan Pluto sesungguhnya berada pada sebuah sabuk atau ring matahari yang diberi nama Sabuk Kuiper (Kuiper Belt). Sabuk ini dihuni oleh banyak sekali objek-objek langit, dan Pluto mewakili objek terbesar penghuni sabuk ini.

Pada 24 Agustus 2006 yang lalu akhirnya diputuskan bahwa pluto bukanlah sebuah planet. Hal ini diputuskan oleh sekitar 2500 orang ahli pada pertemuan di Praha.

Setelah pencopotan status Pluto sebagai planet yang ke sembilan, para Astronomi menemukan planet baru yang bikin istimewa planet tersebut tidak padat seperti layaknya benda langit biasanya, melainkan mengembang ini dinamakan HAT-P-I. Jika planet ini di letakkan dalam air, ia pasti mengapung. Planet ini lebih besar dari yupiter dan hanya butuh 4.5 hari untuk mengelilingi orbitnya dibandingkan dengan bumi yang membutuhkan 365 hari untuk mengelilingi matahari.

Ada juga kandidat pengganti Pluto yang 4 kali lebih besar dari Yupiter yaitu Tyche. Nama itu diambil dari nama dewi Yunani yang menentukan nasib suatu kota. Tyche diduga merupakan planet gas raksasa, jenis planet yang sama seperti Jupiter. Jarak planet ini dengan Matahari mencapai 15.000 kali dari jarak Matahari-Bumi atau 375 kali jarak Matahari-Pluto. Suhu di planet ini 4-5 kali lebih hangat dari Pluto yaitu -73 derajat Celsius.

Neptunus

.

Neptunus  

Neptunus dari wahana Voyager 2
Penemuan
Penemu	Urbain Le Verrier John Couch Adams Johann Galle
Tanggal ditemukan	23 September 1846[1]
Penamaan
Ciri-ciri orbit[2]
Epos J2000
Aphelion	4.553.946.490 km 30,44125206 SA
Perihelion	4.452.940.833 km 29,76607095 SA
Sumbu semi-mayor	4.503.443.661 km 30,10366151 SA
Eksentrisitas	0,011214269
Periode orbit	60.190 hari 164,79 tahun
Periode sinodis	367,49 hari[3]
Kecepatan orbit rata-rata	5,43 km/s[3]
Anomali rata-rata	267,767281°
Inklinasi	1,767975° ke Ekliptika 6,43° ke ekuator Matahari 0,72° ke bidang Invariabel[4]
Bujur node menaik	131,794310°
Argumen perihelion	265,646853°
Satelit	13
Ciri-ciri fisik
Jari-jari khatulistiwa	24.764 ± 15 km[5][6] 3,883 Bumi
Jari-jari kutub	24.341 ± 30 km[5][6] 3,829 Bumi
Kepepatan	0,0171 ± 0,0013
Luas permukaan	7,6408×109 km²[6] 14,98 Bumi
Volume	6,254×1013 km³[3][6] 57,74 Bumi
Massa	1,0243×1026 kg[3] 17,147 Bumi
Massa jenis rata-rata	1,638 g/cm³[3][6]
Gravitasi permukaan di khatulistiwa	11.15 m/s²[3][6] 1.14 g
Kecepatan lepas	23,5 km/s[3][6]
Hari sideris	0,6713 hari[3] 16 j 6 men 36 d
Kecepatan rotasi	2,68 km/det 9,660 km/jam
Kemiringan sumbu	28,32°[3]
Asensio rekta bagi Kutub Utara	19j 57m 20d[5]
Deklinasi bagi Kutub Utara	42,950°[5]
Albedo	0,290 (terikat) 0,41 (geometrik)[3]
Suhu permukaan    level 1 bar    0,1 bar (10 kPa)	min rata-rata maks 72 K[3] 55 K[3]
Magnitudo tampak	8,0 sampai 7,78[3]
Diameter sudut	2,2″–2.4″[3]
Atmosfer[3]
Tinggi skala	19,7 ± 0,6 km
Komposisi	80±3,2% Hidrogen (H2) 19±3,2% Helium 1,5±0,5% Metana ~0,019% Hidrogen deuterida (HD) ~0,00015% Etana Es: Amonia Air Amonium hidrosulfida(NH4SH) Metana (?)

Neptunus merupakan planet terjauh (kedelapan) jika ditinjau dari Matahari. Planet ini dinamai dari dewa lautan Romawi. Neptunus merupakan planet terbesar keempat berdasarkan diameter (49.530 km) dan terbesar ketiga berdasarkan massa. Massa Neptunus tercatat 17 kali lebih besar daripada Bumi, dan sedikit lebih besar daripada Uranus.^[7] Neptunus mengorbit Matahari pada jarak 30,1 SA atau sekitar 4.450 juta km. Periode rotasi planet ini adalah 16,1 jam, sedangkan periode revolusinya adalah 164,8 tahun. Simbol astronomisnya adalah ♆, yang merupakan trident dewa Neptunus.
Neptunus ditemukan pada tanggal 23 September 1846.^[1] Planet ini merupakan planet pertama yang ditemukan melalui prediksi matematika. Perubahan yang tak terduga di orbit Uranus membuat Alexis Bouvard menyimpulkan bahwa hal tersebut diakibatkan oleh gangguan gravitasi dari planet yang tak dikenal. Neptunus selanjutnya diamati oleh Johann Galle dalam posisi yang diprediksikan oleh Urbain Le Verrier. Satelit alam terbesarnya, Triton, ditemukan segera sesudahnya, sementara 12 satelit alam lainnya baru ditemukan lewat teleskop pada abad ke-20. Neptunus telah dikunjungi oleh satu wahana angkasa, yaitu Voyager 2, yang terbang melewati planet tersebut pada tanggal 25 Agustus 1989.
Komposisi penyusun planet ini mirip dengan Uranus, dan komposisi keduanya berbeda dari raksasa gas Yupiter dan Saturnus. Atmosfer Neptunus mengandung hidrogen, helium, hidrokarbon, kemungkinan nitrogen, dan kandungan "es" yang besar seperti es air, amonia, dan metana. Astronom kadang-kadang mengategorikan Uranus dan Neptunus sebagai "raksasa es" untuk menekankan perbedaannya.^[8] Seperti Uranus, interior Neptunus terdiri dari es dan batu.^[9] Metana di wilayah terluar planet merupakan salah satu penyebab kenampakan kebiruan Neptunus.^[10]
Sementara atmosfer Uranus relatif tidak berciri, atmosfer Neptunus bersifat aktif dan menunjukkan pola cuaca. Contohnya, pada saat Voyager 2 terbang melewatinya pada tahun 1989, di belahan selatan planet terdapat Titik Gelap Besar yang mirip dengan Titik Merah Besar di Yupiter. Pola cuaca tersebut diakibatkan oleh angin yang sangat kencang, dengan kecepatan hingga 2.100 km/jam.^[11] Karena jaraknya yang jauh dari Matahari, atmosfer luar Neptunus merupakan salah satu tempat terdingin di Tata Surya, dengan suhu terdingin −218 °C (55 K). Suhu di inti planet diperkirakan sebesar 5.400 K (5.000 °C).^[12][13] Neptunus memiliki sistem cincin yang tipis. Sistem cincin tersebut baru dilacaktemu pada tahun 1960-an dan dipastikan keberadaannya oleh Voyager 2 pada tahun 1989.^[14]

b. Saturnus






Saturnus



Saturnus (9,5 SA) yang dikenal dengan sistem cincinnya, memiliki beberapa kesamaan dengan Yupiter, sebagai contoh komposisi atmosfernya. Meskipun Saturnus hanya sebesar 60% volume Yupiter, planet ini hanya seberat kurang dari sepertiga Yupiter atau 95 kali massa bumi, membuat planet ini sebuah planet yang paling tidak padat di Tata Surya. Saturnus memiliki 60 satelit yang diketahui sejauh ini (dan 3 yang belum dipastikan) dua di antaranya Titan dan Enceladus, menunjukan activitas geologis, meski hampir terdiri hanya dari es saja. Titan berukuran lebih besar dariMerkurius dan merupakan satu-satunya satelit di Tata Surya yang memiliki atmosfer yang cukup berarti.
C. Uranus






Uranus



Uranus (19,6 SA) yang memiliki 14 kali massa bumi, adalah planet yang paling ringan di antara planet-planet luar. Planet ini memiliki kelainan ciri orbit. Uranus mengedari matahari dengan sumbu poros 90 derajad padaekliptika. Planet ini memiliki inti yang sangat dingin dibandingkan gas raksasa lainnya dan hanya sedikit memancarkan energi panas. Uranus memiliki 27 satelit yang diketahui, yang terbesar adalah Titania, Oberon, Umbriel, Ariel dan Miranda.

a. Yupiter






Yupiter



Yupiter (5,2 SA), dengan 318 kali massa bumi, adalah 2,5 kali massa dari gabungan seluruh planet lainnya. Kandungan utamanya adalah hidrogendan helium. Sumber panas di dalam Yupiter menyebabkan timbulnya beberapa ciri semi-permanen pada atmosfernya, sebagai contoh pita-pita awan danBintik Merah Raksasa. Sejauh yang diketahui Yupiter memiliki 63 satelit. Empat yang terbesar, Ganymede, Callisto, Io, danEuropa menampakan kemiripan dengan planet kebumian, seperti gunung berapi dan inti yang panas. Ganymede, yang merupakan satelit terbesar di Tata Surya, berukuran lebih besar dari Merkurius.

Venus

.

Venus  

Venus dalam warna asli
Penamaan
Nama alternatif	Zohrah, bintang kejora, bintang timur, bintang barat
Ciri-ciri orbit
Epos J2000
Aphelion	108.942.109 km 0,728 231 28 SA
Perihelion	107.476.259 km 0,718 432 70 SA
Sumbu semi-mayor	108.208.930 km 0,723 332 SA
Eksentrisitas	0,006 8
Periode orbit	224,700 69 hari 0,615 197 0 tahun
Periode sinodis	583,92 hari[1]
Kecepatan orbit rata-rata	35,02 km/s
Inklinasi	3,394 71° ke Ekliptika 3,86° ke ekuator Matahari 2,19° ke bidang variabel[2]
Bujur node menaik	76,670 69°
Argumen perihelion	54,852 29°
Satelit	Tidak
Ciri-ciri fisik
Jari-jari rata-rata	6.051,8 ± 1,0 km[3] 0.949 9 Bumi
Kepepatan	< 0,000 2[3]
Luas permukaan	4,60×108 km² 0.902 Bumi
Volume	9,38×1011 km³ 0.857 Bumi
Massa	4,868 5×1024 kg 0.815 Bumi
Massa jenis rata-rata	5,204 g/cm³
Gravitasi permukaan di khatulistiwa	8,87 m/s2 0,904 g
Kecepatan lepas	10,46 km/s
Hari sideris	243,018 5 hari
Kecepatan rotasi	6,52 km/j
Kemiringan sumbu	177,3°[1]
Asensio rekta bagi Kutub Utara	18 j 11 min 2 d 272,76°[4]
Deklinasi bagi Kutub Utara	67.16°
Albedo	0,65[1]
Suhu permukaan    Kelvin    Celsius	min rata-rata maks 735 K[6][1][7] 461,85 °C
Magnitudo tampak	hingga -4,6[1] (sabit) -3,8[5] (penuh)
Diameter sudut	9,7" — 66,0"[1]
Atmosfer
Tekanan permukaan	9,3 MPa
Komposisi	~96,5% Karbon dioksida ~3,5% Nitrogen 0,015% Belerang dioksida 0,007% Argon 0,002% Uap air 0,001 7% Karbon monoksida 0,001 2% Helium 0,000 7% Neon jejak Karbonil sulfida jejak Hidrogen klorida jejak Hidrogen fluorida

Venus atau Bintang Kejora adalah planet terdekat kedua dari matahari setelah Merkurius. Planet ini memiliki radius 6.052 km, diameter 12.104 km. Atmosfer Venus mengandung 97% karbondioksida (CO₂) dan 3% nitrogen, sehingga hampir tidak mungkin terdapat kehidupan.
Arah rotasi Venus berlawanan dengan arah rotasi planet-planet lain. Selain , itujangka waktu rotasi Venus lebih lama daripada jangka waktu revolusinya dalam mengelilingi Matahari. Kala rotasinya 243 hari, sedangkan kala revolusinya 225 hari.
Kandungan atmosfernya yang pekat dengan CO₂ menyebabkan suhu permukaannya sangat tinggi akibat efek rumah kaca. Suhu permukaannya maksimal 464°C. Lapisan atmosfer Venus memantulkan hampir 80 persen cahaya matahari. Sehingga kita dapat melihat Venus dengan jelas. Atmosfer Venus tebal dan selalu diselubungi oleh awan. Pakar astrobiologi berspekulasi bahwa pada lapisan awan Venus termobakteri tertentu masih dapat melangsungkan kehidupan.
Atmosfer yang tebal menyebabakan permukaan Venus sulit diamati. Namun, hasil pemetaan dengan radar yang dilakukan misi pesawat eksplorasi Magellan, yang diluncurkan pada 4 Mei 1989, menunjukkan permukaan planet Venus tampak penuh kawah dan gunung api.