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Scientific Tools in changing our life

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Astronomical Instruments:

The elegant rings and bands of an armillary sphere (below) symbolize the astronomy of the past. The armillary sphere takes its name from the Latin armilla, meaning a bracelet or metal ring. With the Earth located at the center, the rings trace out what an observer sees in the night sky without a telescope. The outer band, that supports the device, shows the observers horizon and the meridian. Inside these bands is a cagelike assembly of rings that rotate to display the durinal motion of the stars. The zodiac is represented by a broad band marked with the 12 signs.




Locating stars and measuring their positions precisely is no simple task. One of the earliest astronomical instruments is the quadrant, shown below, which measures a stars altitude above the horizon. A quadrant acquires its name by its ability to measure within a quarter circle. Using spherical trigonometry, the zenith distance could then be used to calculate a stars celestial longitude and latitude. Quadrants made of metal allowed finer intervals to be ruled for more precise measurements.




The astrolabe was a sophisticated time-telling instrument of late antiquity. It was an all-in-one tool for calculating the position of the Sun (thus, local time) and various stars. The typical astrolabe has a rotating cutaway disk, called the rete, that represents the heavens as they revolve around us. Labeled points represent stars, the solid band is the zodiac. A plate, or tympan, is fixed beneath the rete and is inscribed with altitude and azimuth coordinates for the particular latitude where the astrolabe is used. Since the astrolabe displays the coordinates of various bright stars, it can also be used to determine the time at night when the Sun is not visible. Astrolabes were of particular interest to the ancient Muslim culture since it provided the direction to Mecca for daily prayers.




The mechanized planetarium, one of the most popular scientific tools of the 1700's, displayed the motion of the planets around the Sun. The operation of the device's carefully crafted mechanisms inspired awe and wonder at the sense of the Universe's divinely imposed stable order. Astronomical knowledge was a mark of education and social status and the ownership of a planetaria gave material evidence of such status. The planetaria below was constructed for King George II.

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Constellations:
Drawn onto the celestial sphere are imaginary shapes called constellations, Latin for `group of stars'. Constellations organize the stars into more easily identifiable groups, thus easier to remember. The exact origin of the constellations is lost, but 48 had been established by ancient Greek times which are called the Ptolemaic constellations after Ptolemy's star catalog in the Almagest. Constellations are often drawn in the shapes of mythical heros and creatures tracing a pattern of stars on the celestial sphere, recorded on a star map.




The illustrators of star catalogs depicted the constellations without reference to the night sky, as a result their images do not resemble the actual patterns or brightnesses of the stars. For many of the constellations it is easy to see where they got their names. For example,




Aquila, the Eagle

Hercules, the Warrior

Scorpius, the Scorpion
Because both Asian and European astronomers lived in the norther hemisphere, constellations were missing around the South Celestial Pole until expeditions to the New World. Shown below, astronomer Amerigo Vespucci maps the Southern Cross (Crux) in 1589.

In ancient China, astronomers held high social position with close connections to the imperial court. Many of the same astronomical instruments used in Europe were also used by Chinese astronomers as shown in the pictograph below. Astronomical knowledge passed from India to China (in return magnetized compass needles were sent to Europe so that Western navigators could sail the open seas).

Chinese astronomers emphasized the close relationship between heaven and Earth. They believed that events in heaven reflected those on the Earth. For example, new occurrences, such as a novae, signaled important changes on Earth. Chinese star charts, shown below, divided the stars into `lunar mansions', similar to constellations. The Milky Way was referred to as the `Yellow River', linking them both to seasonal rainfall.

In all, there are 88 constellation names cataloged by Hipparchus in 100 B.C. To find out more about your favorite constellation, goto Constellation of the Month.
The development of larger telescopes, like Herschel's first telescope shown below, allowed the discovery of many stars invisible to the naked eye.

Stars now filled the areas of the sky that previously seemed empty. By the start of the 19th century, pictorial celestial atlases became impractical, even though astronomers continued to make up new constellations.

Star charts evolved into those that featured the stars as austere points sometimes with boundary lines dividing the sky into regions defined by their old constellation names. Star charts for the general public continued to feature the faint outlines of the earlier star charts, but later took on more geometric shapes.

One of the jobs for astronomers in the 17th and 18th centuries was to educate the public on unusual astronomical events, such as comets and eclipses. Typically this was done using printed information sheets called broadsides. The broadside below explains the science behind a total eclipse of the Sun.

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Star Names:
Hipparchus also developed a simply method of identifying the stars in the sky by using a letter from the Greek alphabet combined with the constellation name.

So, for example, the brightest star in the constellation Orion is Alpha Orion, the second brightest star is Beta Orion, and so on. As more and more stars were cataloged, this system was insufficient. By the 1600's, a system was devised to assign letters to each star in a constellation, roughly by descending brightness, beginning first with the Greek alphabet and then, when those letters were exhausted, continuing with the Roman alphabet. When the letters run out, we use a number 33 Orion, 101 Orion, etc. Some of the very brightest stars have their own names due to their importance to early navigators. For example, Alpha Canis Major is Sirius, the Dog Star.

About 6000 stars are visible with the naked eye on a dark, moonless night. However, there are over 10¹³ stars in the whole Milky Way galaxy were the solar system resides. Thus, we only see a very small fraction of the closest and brightest stars with our eyes.

Since the Earth's axis is tilted 23 1/2 degrees from the plane of our orbit around the Sun, The apparent motion of the Sun through the sky during the year is a circle that is inclined 23 1/2 degrees from the celestial equator. This circle is called the ecliptic and passes through 12 of the 88 constellations that we call the zodiac.

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Observatories:
The first need for astronomical observatories was time and calendar keeping. Ancient civilizations referenced astronomical events to mark the reigns of various kings. Civil calendars were derived from the lunar calendar sometime in the 3rd millennium B.C.
The Egyptians constructed the pyramids for tracking Sirius, the Dog Star, in the sky. When Sirius became visible above the horizon, then it was known that the Nile was going to flood, an important time to plant crops.

In Mesopotamia ziggurats were constructed of mud brick to observe the position of the Moon and planets, again to mark the passage of time.

However, no astronomical instruments appears to be used other than the buildings themselves. The first extensive system of astronomical tools was Stonehenge.
The job of early observatories was to map the sky, so the earliest astronomical instrument was the quadrant or sextant. Using these instruments, Hipparchus at Rhodes (150 B.C.) produced the first star catalog, measured precession and developed the magnitude system of stellar brightness. Islamic observatories at Damascus and Baghdad tested our first solar system models.
The first modern observatory was constructed in Denmark by Tycho Brahe in 1576.

With the invention of optics, observatories added telescopes to their collection of instruments. Telescopes serve to 1) magnify nearby planets, to study surface features, 2) collect light to detect faint stars and 3) transfer light to recording instruments, such as a photographic plate to take a picture, or to a spectrograph to take a spectrum.
Due to effects of the atmosphere, telescopes are typically located on mountain tops because

1. they are dry sites (few clouds),
2. high above the thick currents of air so the images are clear and steady and
3. to allow more UV (ultraviolet) and IR (infrared) photons which are blocked by lower atmosphere.

Our national telescopes are located at Kitt Peak in Arizona for the northern hemisphere and Chile for the southern hemisphere (you can't see southern constellations from the northern hemisphere, nor northern ones from the southern hemisphere).

Optical astronomy has dominated for centuries until the development of space telescopes. To observe at high energies (gamma and x-rays) or in the far-IR and microwave regions of the spectrum, the telescope must be located above the Earth's atmosphere.
For example, this orbiting IR telescope, launched in 1994:

The AXAF/Chandra X-ray telescope, now in orbit:

and a shuttle launched gamma-ray telescope, now de-orbited:

Space observatories have an advantage even in regions of the spectrum that we can see from the ground (i.e. the visible region of the spectrum). Being above the atmosphere means being able to resolve stars and galaxies to much finer detail than ever seen before, and the flagship of space telescopes is the Hubble Space Telescope shown below.

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Optical Telescopes:
The simplest telescope is two lens separated by a tube. Since the objective lens (the front lens) refracts the incoming light, this kind of instrument is called a refracting telescope.


Note that the objective lens brings the incoming light to a focus, and then the eyepiece magnifies that focal region for the eye. So it is a combination of a lens and microscope. Galileo used this type of telescope to discover the phases of Venus and the moons of Jupiter. The type of telescope you would buy today looks like the following:

The objective lens is surrounded by a series of baffles to block stray light. A small mirror is placed near the complicated eyepiece to turn the light upward from the telescope for a more comfortable viewing position.
The limitation on refracting telescopes is that glass is only a semi-solid and will deform with time. So very large lens will not stay round, plus they are extremely heavy. For these reasons, the largest refracting telescope is limited to 40 inches in diameter.
In order to build larger telescopes to gather more light to see fainter stars, most optical telescopes employ a reflecting telescope design invented by Newton. In this case, a large concave mirror reflects the incoming light into a focal point. Four different reflecting designs are used, depending on where the focal point is placed.

The various focus designs relate to a telescopes use. For example, a prime focus system is poor on small telescopes because your head gets in the way. So most commercial telescopes have a Newtonian design. However, for large telescopes (greater than 2 meters in mirror size), the prime focus system is use since it has a minimal number of optical elements in the way to distort light.

If a heavy instrument is used on the telescope, for example a CCD camera, then the instrument must be placed at the cassegrain focus. If an extremely heavy instrument is used, then the stellar light is reflected down the axis of the telescope into separate machine rooms below the telescope. This is called a Coude design.

The larger the telescope, the more light gathering power, the fainter the stars you can measure. But there is a limit to the size of a primary mirror given by the ability for glass to support it own weight (it flows and cracks under stress). For a refracting telescope, the limit for the diameter of the objective lens is about 48 inches. For a reflecting telescope, the limit of the size of a single primary mirror is about 8 meters. The Keck twins are the largest telescopes in the world, using a new technology of a segmented primary to make a 10 meter mirror.

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Radio Telescopes:
Radio telescopes gather radio waves from stellar objects. Since radio waves are reflected by metal, they are typical made of solid aluminum or steel mesh.

The difference wavelength of the light in the radio region (centimeters and meters) means a different technology to analysis them. In the case of radio astronomy, a sophisticated radio receiver is used such that the power of the telescope is determined by the area of the antenna and the sensitivity of the electronics.
Radio telescopes can also use the phenomenon of interference to obtain high resolution. Many antennas, working together, measure the interference patterns from distant sources and combine them to produce highly detailed maps in the radio region of the spectrum. An example is the Very Large Array shown below.

Since radio telescopes are made of metal, and not glass, they can be made very large. An extreme example of this is the Arecibo Telescope in Puerto Rico, strung between two mountain ranges in Puerto Rico.

Scientific Theories, Discoveries, News and Facts

Science and research are two words or concepts that so closely related that they are almost interchangeable with one another. Science can best be described as systematic gathering of knowledge of the world and its occurrences and phenomena through observation and experimentation. Research can be defined as a systematic approach to gather information and [...]

Scientific Theories

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In the scientific world, experiments and various types of studies are used to compile a collection of data and results. According to the scientific method, the data obtained from experiments used to explain a hypothesis must able to be repeated in order to conclude any validity to the final claims or results. Furthermore, [...]

Science Discoveries

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The study of science allows for amazing discoveries for occur everyday. The natural world is constantly changing, and therefore, new knowledge about our immediate environment is there to be gained. It is through forward progress in the fields of science and technology that scientist can explore the realms of possibility to gain new [...]

Science News

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Science is will always be constant flux because it deals the nature of knowledge. Science encompasses such a vast amount of knowledge that the human mind can not possibly fathom. Furthermore, because science essentially deals with the changes of the natural, it is impossible to put any kind of quantifiable value to the [...]

Scientific Facts

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Science facts can refer to findings and conclusions carried out by experiments to help validate a particular hypothesis. Because scientific findings are corrugated by extensive research, experiments, data, and a methodical approach and logic, it may be argued that those things that may be considered as scientific facts are the most true in the [...]

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Engineer the tools of scientific discovery

In the century ahead, engineers will continue to be partners with scientists in the great quest for understanding many unanswered questions of nature.

In the popular mind, scientists and engineers have distinct job descriptions. Scientists explore, experiment, and discover; engineers create, design, and build.

But in truth, the distinction is blurry, and engineers participate in the scientific process of discovery in many ways. Grand experiments and missions of exploration always need engineering expertise to design the tools, instruments, and systems that make it possible to acquire new knowledge about the physical and biological worlds.
In the century ahead, engineers will continue to be partners with scientists in the great quest for understanding many unanswered questions of nature.

How will engineering impact biological research?

Biologists are always seeking, for instance, better tools for imaging the body and the brain. Many mysteries also remain in the catalog of human genes involving exactly how genes work in processes of activation and inhibition. Scientists still have much to learn about the relationship of genes and disease, as well as the possible role of large sections of our DNA that seem to be junk with no function, leftover from evolution.
To explore such realms, biologists will depend on engineering help — perhaps in the form of new kinds of microscopes, or new biochemical methods of probing the body’s cellular and molecular machinations. New mathematical and computing methods, incorporated into the emerging discipline of “systems biology,” may show the way to better treatments of disease and better understanding of healthy life. Perhaps even more intriguing, the bioengineering discipline known as “synthetic biology” may enable the design of entirely novel biological chemicals and systems that could prove useful in applications ranging from fuels to medicines to environmental cleanup and more.
Turning to the mysteries of our own minds, new methods for studying the brain should assist the study of memory, learning, emotions, and thought. In the process, mental disorders may be conquered and learning and thinking skills enhanced. Ultimately, such advances may lead to a credible answer to the deepest of human mysteries, the question of the origin and nature of consciousness itself.

How will engineering help

Priority environment and health risks

Priority risks: The human toll

• Download full policy brief: Priority risks and future trends

Environmental factors are a root cause of a significant disease burden, particularly in developing countries. An estimated 25% of death and disease globally, and nearly 35% in regions such as sub-Saharan Africa, is linked to environmental hazards. Some key areas of risk include the following:

• Unsafe water, poor sanitation and hygiene kill an estimated 1.7 million people annually, particularly as a result of diarrhoeal disease.
• Indoor smoke from solid fuels kills an estimated 1.6 million people annually due to respiratory diseases.
• Malaria kills over 1.2 million people annually, mostly African children under the age of five. Poorly designed irrigation and water systems, inadequate housing, poor waste disposal and water storage, deforestation and loss of biodiversity, all may be contributing factors to the most common vector-borne diseases including malaria, dengue and leishmaniasis.
• Urban air pollution generated by vehicles, industries and energy production kills approximately 800 000 people annually.
• Unintentional acute poisonings kill 355 000 people globally each year. In developing countries, where two-thirds of these deaths occur, such poisonings are associated strongly with excessive exposure to, and inappropriate use of, toxic chemicals and pesticides present in occupational and/or domestic environments.
• Climate change impacts including more extreme weather events, changed patterns of disease and effects on agricultural production, are estimated to cause over 150 000 deaths annually.