McWill SCDMA Wireless Access Technology Computer Science Essay

McWill SCDMA Wireless Access Technology Computer Science Essay McWiLL is the most advanced broadband wireless solution provided by Beijing Xinwei Telecommunications Technology. The technology is based on SCDMA, and is known as Multicarrier Wireless information Local Loop (McWiLL). McWiLL combines SCDMAs traditional use in narrow-band voice and introduces a mobile broadband data service that ties into an IP-based core network. It is based on CS-OFDMA adaptive modulation, and uses dynamic channel allocation and smart antennas to enhance its throughput. SCDMA is a wireless access technology developed by Beijing Xinwei Telecom Technology Co., Ltd. The SCDMA air interface is a national wireless access standard in China. The SCDMA products contains a full suite of advanced wireless communication and networking technologies, such as smart antennas. The key technologies of SCDMA form the foundation of TD-SCDMA, an ITU Standard for 3G Wireless Communications. Earlier SCDMA products are narrowband products focusing on fixed and mobile voice applications. A new generation of SCDMA products are broadband products, Multicarrier Wireless Internet Local Loop (McWiLL), focusing on fixed and mobile voice and high speed data application. McWiLL has been deployed in several Chinese cities, including Guangzhou and Qingdao, where its been used for video, voice and data communication. McWiLL successfully served for 2008 Beijing Olympic Regatta, providing the high-definition, real-time mobile video services. Internationally it has been deployed in more than fifteen countries, such as USA, Cameroon, Nigeria, Ukraine, Malawi, and Mozambique. McWiLL is a TDD-based wireless access platform that combines SCDMA (synchronous CDMA), CS-OFDM (code spreading orthogonal frequency division multiple access), MIMO and smart antennas, as well as other wireless techniques such as adaptive modulation (up to QAM64), dynamic channel allocation and make-before-break handoff, to offer a high-speed data and voice services. All these features are designed to work with any IP core network and provide up to 15Mbps of data rate using 5MHz of spectrum. http://oksunpeng.blogspot.com/ In a way, McWiLL tries to incorporate all of todays wireless networking techniques into a single platform which is very possibly why it is almost impossible for a normal human to understand. McWiLL Base Station supports the following features: (a) Support up to 15Mbps net throughput with 5MHz bandwidth; (b) Support fixed and mobile, voice and data services; (c) Support up to 163dB link budget; (d) Support Make-before-Break handoff and L2 tunnel; (e) Support QoS and GoS features; (f) Support Over-the-Air upgrade; (g) Support low power consumption (150 Watt); (e) Support VLAN, PPPoE and penetration of private networks http://oksunpeng.blogspot.com/2009/03/what-is-mcwill.html McWill(Multi-carrier Wireless Information Local Loop) is a mobile broadband access system based on SCDMA technology platform. McWiLL Technology Smart Antennas Dynamic Channel Assignment Code Spread OFDMA (CS-OFDMA) Time Division Duplex (TDD) Efficient VoIP Technology Make-before-Break Baton Handoff Adaptive Modulation QoS GoS Security Fraud Protection McWiLL System Features Main Services ¼Ã… ¡Fixed, portable, mobile voice and data communications. Main Features ¼Ã… ¡BTS with 5MHz can support up to 15Mbps net throughput, each sector can support more than 300 simultaneous sessions, supporting high-speed mobility, handoff and roaming, N=1 frequency planning, and low latency. Product Characteristics: Support up to 100KM/H mobile speed Terminals are backward compatible Support efficient voice communications and low-bandwidth data. Support N=11 deployment. Products available in the following frequencies: 336-344MHz, 400-430MHz, 698-746MHz,1785MHz-1805MHz, 2150-2180MHz, 2525-2560MHz, 3300-3400MHz Characteristics of Chinese Rural Areas Challenges ¼Ã… ¡ Low subscriber density, large separation of villages, far away from urban areas Complicated environment (mountainous and hilly terrain) Poor facility (backhaul, power supply, etc.) Low income Current wireline/wireless communication systems cannot meet these challenges Low ARPU Less than $4/month in most areas Busty traffic High traffic especially in Chinese traditional holidays Asymmetric traffic More incoming calls than outgoing calls Little usage of value added services Unique Advantages of Deploying McWiLL Large coverage enables fewer cell sites which are expensive in developing countries, leading to much lower Capex and Opex. N=1 deployment enables a wide area network with as little as 5MHz spectrum, leading to much lower upfront investment on spectrum which is usually quite expensive. Products with a wide range of frequency allow an operator to choose the most cost effective spectrum to operate. Lower terminal cost and adequate data rates allow an operator to minimize the Opex and lower the entry barriers for a subscriber. Most McWiLL terminals can support both voice and data services. GSM/McWiLL dual mode handsets/PDAs allow an end user to enjoy 3G beyond performance of McWiLL data and cost effective voice without sacrificing easy access advantages of GSM. Summary of McWiLL Advantages Large coverage (up to 60Km) Smart antenna,400MHz frequency band Low cost Already large volume, cost effective architecture, SCDMA ASIC chipset, no royalty fees, low RD cost, low manufacture cost, multiple vendors due to SCDMA Alliance High capacity BTS capacity 24Mbps/10MHz ¼Ã…’supporting up to 8,000 voice subscribers One system fits all Via flexible configuration, one system can meet the requirements of different user groups (high-end and low-end), services (voice and data), and time (current and future). Product maturity and reliability 10 years RD, large scale deployment, redundancy architecture, long time operational networks, an experienced team of installation and customer support. Easy to install and maintenance Terminal zero install, easy-to-use tools for customer self debugging, remote access trouble shooting tools for support personnel. Abstract In this presentation, we will first give an introduction of popular wireless multiplex technologies such as WCDMA and OFDMA and then present our McWiLL technology which is an optimal integration of WCDMA and OFDMA technologies to effectively address the technical challenges of wireless broadband access, such as capacity, coverage, multipath fading, and intercell interference. In other words, McWiLL effectively avoids the major drawbacks of WCDMA and OFDMA and draws their advantages of both technologies. Unlike voice centric WCDMA or data centric OFDMA (WiMax), the McWiLL wireless broadband access system can efficiently combines both voice and data applications. Finally, we will provide brief introduction of McWiLL product roadmap and application. McWiLL Fits Chinese Rural Markets à ¢Ã¢â€š ¬Ã‚ ¢ Smart antenna and 400MHz frequency band allows the McWiLL systems to have large NLOS coverage (up to 60KM). à ¢Ã¢â€š ¬Ã‚ ¢ Multicarrier BTS can support up to 8,000 voice subscribers having sufficiently high capacity to support bursty traffic in rural applications. à ¢Ã¢â€š ¬Ã‚ ¢ Cost effective architecture and SCDMA ASICs allow the McWiLL products to have sufficiently low cost per line ($60-80 overall cost per line including both terminal and infrastructure). à ¢Ã¢â€š ¬Ã‚ ¢ Zero install of McWiLL terminals and rich tools for self and remote troubleshooting make it very easy to deploy the McWiLL systems in rural areas. à ¢Ã¢â€š ¬Ã‚ ¢ 10 years RD, redundancy architecture and large-scale deployment (>2 million subscribers) make the McWiLL products mature and reliable enough to deploy in remote rural areas. à ¢Ã¢â€š ¬Ã‚ ¢ Integrated voice and data solutions can allow the McWiLL systems to meet both current and future service requirements of rural customers. My opinion Multicarrier Wireless Internet Local Loop (McWill) is developed by Beijing Xinwei Telecom Technology Co., Ltd. It is a wireless access technology which can cover for the very large area, its coverage can up to 60KM. Therefore it is very suitable for china because it is a big country. Its been used for video, voice and data communication and successfully served for 2008 Beijing Olympic. Even though McWill is very popular but it cannot be use for every country for example, Singapore. Singapore is a small country if using the technology of McWill, there will be a lot of wasted.

Leadership Theories/ Approaches Essay

As individuals, all seek to improve their personal, social and professional roles. As organizations, they seek people able to guide others and maximize performance. One of the thoughts that come to people on this is to achieve Leadership but to be able to do it, it is imperative to understand its meaning, its strengths, its weaknesses and all concepts that may help individuals and organizations to approach it in their modern world. Thanks to these needs, many researchers have been looking for answers and ways to represent what is leadership significance. The purpose of this essay is to analyze and discuss two theories/approaches of leadership, in order to gain a better understanding. Every individual experiments the meaning of leadership (in family, school, playground, politics, professional work, among others). Some studies present leadership as a trait or behavior and some others from an information perspective or relational position and to be studied qualitative and quantitative m ethods have been applied in varied contexts (Northouse, 2009). Behave as a leader determinates success in individual ´s careers and outcome in organizations, in other words leadership behavior leads in effectiveness (Lussier and Achua, 2009). Theorist agreed that the perspective or how leadership is interpreted can be divided in two groups: Classical and contemporary theoretical approaches. To focus in modern views could mean to pass over the classical views such as the traits approach, behavior or style approach and the situational approach which are often condemned because according to some authors, it does not cover the whole reality (Winkler, 2009).To discuss this point one of the classics views of leadership as the situational approach is and one modern approach as transformational approach will be developed. Classical approaches undertake just one directional relation between leaders and followers where leaders have particular trait that differentiate them from those who follow them while most of the contemporaries approach consider it a s an interaction process (Winkler, 2009). Classical theories describe characteristics and behavior of leaders (Rost, 1991), opposite of modern approaches which seem it as a complex interaction (Yuki, 2006). Situational approach is one of the most known and diverse approaches of leadership, developed by Hersey and Blanchard (1969) based on Reddin ´s (1967). This approach says that different kinds of leadership are required for each different situation which can be inferred as the ability of adaptability to different environments to be an effective leader. Situational approach demands that there are a directive and supportive dimensions which compose it and they are highly important to be applied fittingly to the situation involved. In order to determinate what is required a leader, must understand the scenario and evaluate the employees to identify their skills to perform a task given and after the analysis to choose the level of being directive and supportive (Northouse, 2009). There are cases when one is more suitable than the other. Everything depends on the situation. In other words it means that a leader is called to match their style to the skills of their employees. The most effective leader is who match her or his own style to employees ‘needs. Blanchard (1985) and Blanchard et al (1985) provided a model of situational approaches which was based on the previous model described by Hersey and Blanchard (1969. Situational Leadership. Taken from Blanchard et all (1985). To better understanding the dynamics of situational approach can be divided into two: Leadership styles and Development level of subordinates (Northouse, 2009). The former makes reference to the behavior pattern of a person who seeks influencing others, including the directive or task oriented behavior and the supportive or relationship oriented behavior. According to the graphic below the leadership styles can be discriminated in 4 categories: supportive, coaching, directive and delegating style which is described under each one depending on the levels of directive or supportive behavior assumed. Development levels calls the level of commitment from the employees. It goes from low to high level depending on the interest and confidence on the employees in their work. To mention some of the strengths of the situational approach it is convenient to mention that it give emphasis to the leader flexibility (Graeff, 1983). Leaders need to know their subordinate ´s aims and accommodate to them. Employees do not act or react in the same way for all tasks provided, they distinguish between each one and their behavior is different in each situation, so leaders (Northouse, 2009). Least but not less, situational leadership reminds leaders to treat each subordinate different, according to the task (Fernandez and Vecchio, 1997). On the other hand, there is not enough evidence of research in this field to maintain the theoretical basis (Fernandez and Vecchio, 1997). When looking at Blanchard’s model there is kind of ambiguity because there is not clear relation or combination between commitment and competence in subordinates (Graeff, 1997). To determinate the validity of the relationship established by Hersey and Blanchard ´s model, Vecchio (1987) carried out a test with more of 300 hundred schools and found that teacher new hired whit high structured styles leadership were performing better while experienced teachers were indifferent to the leadership style of the principal (Northouse, 2009). Even when criticized this approach has still some application areas such as consulting because of its easy conceptualization and application. Situational leadership for instance can be applied in the first stage of a project when the conception of the idea is important (Northouse, 2009). To help the reader to understand more about situational approach there are two situations described Situation 1 Budget restrictions were set in the department and a project must be consolidated. The manager thinks to pass this responsibility to an employee who is highly capable and with so much experience. This employee is well known and respected by most if the rest of the staff (Adapted from Northouse (2009)). In this particular situation which actually is faced frequently by organizations, the style of the manager or leader which was assumed is the â€Å"delegating style† when through delegating the accomplishment of the task to the employee is performing a low directive level and low supportive level when is asking the employee to be in charge and because of the capabilities of the employee is allowing them to decide how to do it. Situation 2 Someone was recently named head of a department in a new regional office. When knowing the staff, noticed that one of the experienced employees do not follow the tasks assigned who is new and very enthusiastic and wants to get ahead in the organization (Adapted from Northouse (2009)). . This case describes a very often situation where organizations find some enthusiastic employees who fail following tasks. Because of the lack of experience of the employee but the high motivations to succeed, the most suitable leadership style would be â€Å"Directing†. The employee requires to be told about the specifications of each task of the job and also the performance needs to be monitored. A more contemporary approach is the transformational leadership which stands for creation of a valuable change positive to followers. A transformational leader focuses on transforming others, helping each other to motivate people and maximize the performance of individuals. In particular this leadership approach was created to provide a framework that stop leaders of adopting the last leader style of the day found in any book store. In the nature of transformational leadership consciousness is inherent and also the ability to raise consciousness in others (Hacker and Roberts, 2003). The skills aimed are managerial and leadership and certainness of when call one style on a particular situation (Hacker and Roberts, 2003). Transformational leaders motivate their followers to do more than what they think is possible to do achieving better performances (Bass, 1998). Leaders applied one or more of the four components of the transformational leadership. According to Bass and Avolio (1990) leaders who achieved high performance results, employ the four components: charismatics or idealized influence, Inspirational motivation, intellectual stimulation and Individualized consideration. The former is when followers identify the leader as an example and make it a model. Those leaders obtain the best of the followers because they gain their trust and respect. The inspirational leader, encourage their followers in a positive way and show them security when present their future plans, stimulating people to achieve high performance levels (Bass, 1985). When they stimulate the intellect of their followers, they enhance their creativity and persuade them to re think the ideas to solve a problem. The later, individualized consideration is applied when leaders diagnostic the needs and characteristics of their followers and care about each individual. Into a changing environment, the best leaders are those who are able to create consciousness in their followers about what they do (Bass, 1987). This kind of leadership happens when leaders get their followers highly compromised with their objective into an organization, make then ware of their needs of personal growth, development and achievement of goals, and when motivate them to work well for the general benefit of the organization and not just the personal benefit. An organization having conscious relationships with purpose and direction builds a strong environment to insert radical change (Hacker and Roberts, 2003). Relational transformation and consciousness. Taken from Hacker and Roberts (2003) To illustrate transformational results into an organization the example of leadership in St. Charles medical system, Bend, Oregon (Adapted from Hacker and Roberts, 2003) will be used. Mr. Jim Lussier Leadership position: CEO Organization: St. Charles medical system, Bend, Oregon Transformational results: In 1989, Jim Lussier projected to transform St. Charles Medical Center (SCMC) Jim ´s vision charmed people over the world, resulting in varied questioning about existing hypotheses. The innovative results of reduced costs, reduced lengths of stay, greater patient satisfaction, award-winning service and a long waiting list of nurses seeking being employed, reveal the skills of leader transformation and structuring an organization of meaning. SCMC proved that real caring can coming back to the medical system which for many patients is currently a non-existing service. And for many doctors, nurses and other caregivers they system where they practice is not alive. SCMC under Jim ´s leadership has evidenced something unique that other medical services do not have. To construct his successful approach, Jim employed over 250 task forces to analyze which changes must be done. Through a process of five years Jim and his team redefined the healthcare delivered service, pointing that the spirit of love and compassion must be enhanced to technology and intellect in curing the body. Every process and procedure was reengineered and the healthcare givers were trained in patient-relationship basis, the staff was encouraged to innovate and be creative. When Jim Lussier was asked: How did you build your vision and involve others in? He commented that he created his vision in a personal level and with his mind clear and with the perception of their job as creation of continuum services in order to improve health. He was positive convinced that what they needed were people with a mission in their lives to work with them. Jim ´s statement evidences what the transformational leadership seeks in a leader, it is to get people clear in their minds about his projections and through that get followers that want to take part and improve themselves offering their best. After considering both approaches the author of this essay establishes that even when both were attempted in different times, both are the answers that at their moments were given by the researchers that were interested in improve the performance of organizations. The classical approach discussed which was the situational leadership by its moment found that the style of leaders which Blanchard et al (1985) characterized in four styles (Supporting, Directing, Coaching and delegating) according to the levels of direction and support were related to the commitment and knowledge of subordinates. How the leader behaves influences their subordinates and generates the outcomes into an organization. In a more contemporary scenario where it is recognized that changes happen all the time the requirements of any organizations are based on leaders able to respond to them maximizing the outputs and following the recognition of humans as essential element. So that, leaders were call to establish closer relationships with their teams, to study them, identify their needs and inspire them to perform a greater levels. A leader in the current scenario of business needs to be highly motivator and creative to get others involved in his/her visions. In the author ´s view the characteristics, skill, behavior, among others of a leader are closely related to the business environment where leadership has place. The must be adjusted to the needs and vision of the organization where they exercise it and always procuring to elevates the performance of individuals, gaining their respect, trust, and common commitment. What the author understands as leadership is that it is how individuals obtain enhance employees with organization ´s vision behaving as every particular situation requires, doing it efficiently (do things right) and effectively (doing the right thing). Every individual desiring to be a leader must understand their environment and establish consolidated strategies in order to performance as one. Everyone conscious of themselves, capable of identify their weaknesses and strengths can behave as a leader. REFERENCES Aaker, D.A., Joachimsthaler, E., 2005. Liderazgo de Marca. Deusto Bass, Bernard M. (1981); â€Å"Stogdill’s Handbook of Leadership: A Survey of Theory and Research†. New York: Free Press Bass, B.M., 1998. Transformational Leadership: Industrial, Military, and Educational Impact. Routledge. Bass, B.M., Avolio, B.J., 1994. Improving Organizational Effectiveness through Transformational Leadership. SAGE Hacker, S. & Roberts, T., 2003. Transformational Leadership: Creating Organizations of Meaning. ASQ Quality Press. Hersey, P., & Blanchard, K. H (1988). Management of organizational behavior: Utilizing human resources (6th. Ed.) Englewood Cliffs, NJ: Prentice Hall Lussier, R.N., Achua, C.F., 2009. Leadership: Theory, Application, & Skill Development. Cengage Learning. Northouse, P.G., 2009. Leadership: Theory and Practice. SAGE. Reddin, W. J. (1967, April). The 3-D management style theory. Training and development Journal, pp 8 -17 Vecchio, R.P (1987). Situational leadership theory: An examination of a prescriptive theory. Journal of Applied Psychology, 72(3), 444-451 Winkler, I., 2009. Contemporary Leadership Theories: Enhancing the Understanding of the Complexity, Subjectivity and Dynamic of Leadership. Springer.

Hunger Games Essay Essay

In the novel The Hunger Games by Suzanne Collins the characters are put to the ultimate test to survive or end up dead. In dangerous and life threatening wilderness situations, one needs hunting skills, physical strength and mental strength in order to overcome the odds. One needs hunting skills to overcome the odds in a dangerous or life threatening wilderness situation. Peeta mentions Katniss’s hunting skills â€Å"She’s excellent, my father always comments on how the arrow never pierces the body, she this everyone in the eye†. This quote shows that if Katniss is ever starving she can rely on her skills to guarantee her a kill. Katniss also killed a deer with her bow, so she could provide food for her family so they did not starve and die. If you did not have good skills with a bow you would not be able to take down a deer, and if you relied on that for food you would probably starve. Also when Katniss finds the careers supplies she shoots the bag of apples so they fall and trigger the mines. By shooting the bag of apples it shows how accurate Katniss is with a bow, you also need this accuracy for hunting and killing in the games, and real life to guarantee a kill. Along with hunting skills one will need physical strength to overcome the odds in a life threatening wilderness situation. Katniss: â€Å"I’m fast though, and by the time they’ve reached the base of my trunk I’m twenty feet up†. If you were out in the wilderness and you had to climb a tree you would need physical strength like Katniss had. Another example of physical strength, Katniss: â€Å"I can see the muscles ripple in Cato’s arms as he sharply jerks the boys head to the side†. When Cato kills the boy it shows that you will need physical strength if you ever had to engage in hand to hand combat. Along with hunting skills and physical strength you also need to have mental strength. Katniss: â€Å"the Tracker Jackers begin to buzz and I can hear them coming out, back and forth, back and forth, the branch with the nest crashes down through the lower branches†. Sometimes you will just have to push through things, even if they hurt and in the end it will pay off, you just have to want it bad enough. Another example of mental strength is when Katniss is forced to pretend to love Peeta.

Astronomy 101 The Basics of Learning Astronomy

Astronomy is one of humanitys oldest sciences. Its basic activity is to study the sky and learn about what we see in the universe. Observational astronomy is an activity that amateur observers enjoy as a hobby and pastime and was the first type of astronomy humans did. There are millions of people in the world who stargaze regularly from their backyards or personal observatories. Most arent necessarily trained in the science, but simply love to watch the stars. Others are trained but do not make their living at doing the science of astronomy.   On the professional research side, there are more than 11,000 astronomers  who are trained to do in-depth studies of the stars and galaxies. From them and their work, we get our basic understanding of the universe.  Its such an interesting topic and raises many astronomy-related questions in peoples minds about the cosmos itself, how it got started, whats out there, and how we explore it. Astronomy Basics   When people hear the word astronomy, they usually think of stargazing. Thats actually how it got started — by people looking at the sky and charting what they saw. Astronomy comes from two old Greek terms astron  for star and nomia  for law, or laws of the stars. That idea actually underlies the history of astronomy: a long road of figuring out what objects in the sky are and what laws of nature govern them. To reach an understanding of cosmic objects, people had to do a lot of observing. That showed them the motions of objects in the sky, and led to the first scientific comprehension of what they might be. Throughout human history, people have done astronomy and eventually found that their observations of the sky gave them clues to the passage of time. It should be no surprise that people began to to use the sky more than 15,000 years ago. It provided handy keys for navigation and calendar-making thousands of years ago. With the invention of such tools as the telescope, observers began to learn more about the physical characteristics of the stars and planets, which led them to wonder about their origins. The study of the sky moved from a cultural and civic practice to the realm of science and mathematics.   The Stars So, what are the main targets that astronomers study? Lets start with stars — the heart of astronomy studies. Our Sun is a star, one of perhaps a trillion stars in the Milky Way Galaxy.The galaxy itself is one of countless galaxies in the universe. Each one contains huge populations of stars. Galaxies themselves are collected together into clusters and superclusters that make up what astronomers call the large-scale structure of the universe. The Planets Our own solar system is an active area of study. Early observers noticed that most stars did not appear to move. But, there were objects that seemed to wander against the backdrop of stars. Some moved slowly, others relatively quickly throughout the year. They called these planetes, the Greek word for wanderers. Today, we simply call them planets. There are also asteroids and comets out there, which scientists study as well.   Deep Space Stars and planets arent the only thing that populate the galaxy. Giant clouds of gas and dust, called nebulae (the Greek plural term for clouds) are also out there. These are places where stars are born, or sometimes are simply the remains of stars that have died. Some of the weirdest dead stars are actually neutron stars and black holes. Then, there are quasars, and weird beasts called magnetars, as well as colliding galaxies, and much more. Beyond our own galaxy (the Milky Way), lie an amazing collection of galaxies ranging from spirals like our own to lenticular-shaped ones, spherical, and even irregular galaxies. Studying the Universe   As you can see, astronomy turns out to be a complex subject and it requires several other scientific disciplines to help solve the mysteries  of the cosmos.To do a proper study of astronomy topics, astronomers combine aspects of mathematics, chemistry, geology, biology, and physics.   The science of astronomy is  broken into separate sub-disciplines. For example, planetary scientists study worlds (planets, moons, rings, asteroids, and comets) within our own  solar system  as well as those orbiting distant stars. Solar physicists focus on the Sun and its effects on the solar system. Their work also helps forecast solar activity such as flares, mass ejections, and sunspots. Astrophysicists apply physics to the studies of stars and galaxies to explain exactly how they work.  Radio astronomers use radio telescopes to study the radio frequencies given off by objects and processes in the universe. Ultraviolet, x-ray, gamma-ray, and infrared astronomy reveals the cosmos in other wavelengths of light. Astrometry is the science of measuring distances in space between objects. There are also mathematical astronomers who use numbers, calculations, computers, and statistics to explain what others observe in the cosmos. Finally, cosmologists study the universe as a whole to help explain its origin and evolution across nearly 14 billion years of time. Astronomy Tools   Astronomers use observatories equipped with powerful telescopes that help them magnify the view of dim and distant objects in the universe. Astronomy tools, like the armillary sphere, were used by early astronomers and new tools came about as the study of astronomy evolved. They also use instruments called spectrographs that dissect the light from stars, planets, galaxies, and nebulae, and reveal more details about how they work. Specialized light meters (called photometers) help them measure the varying stellar brightnesses. Well-equipped observatories are scattered around the planet. They also orbit high above Earths surface, with such spacecraft as Hubble Space Telescope providing clear images and data from space. To study distant worlds, planetary scientists send spacecraft on long-term expeditions, Mars landers such as Curiosity, Cassini Saturn mission, and many, many others. Those probes also carry instruments and cameras that provide data about their targets.   Why Study Astronomy? Looking at the stars and galaxies helps us understand how our universe came into being and how it works. For example, knowledge of the Sun helps explain stars. Studying other stars gives insight into how the Sun works. As we study more distant stars, we learn more about the Milky Way. Mapping our galaxy tells us about its history and what conditions existed that helped our solar system form. Charting other galaxies as far as we can detect teaches lessons about the larger cosmos.There is always something to learn in astronomy. Each object and event tells a tale of cosmic history. In a very real sense, astronomy gives us a sense of our place in the universe. The late astronomer Carl Sagan put it very succinctly when he stated, The cosmos is within us. We are made of star-stuff. We are a way for the universe to know itself.