Learn More about the Bright Star Sirius

Sirius, also known as the Dog Star, is the brightest star in our night-time sky. Its also  the sixth closest star to Earth, at a distance of  8.6 light-years. (A light-year is the distance that light travels in a year). The name Sirius comes from the ancient Greek word for scorching and it has fascinated observers throughout human history because of its brightness and colorful twinkling. Astronomers began seriously studying Sirius in the 1800s, and continue to do so today. It is usually noted on star maps and charts as alpha Canis Majoris, the brightest star in the constellation Canis Major (the Big Dog).  Sirius is visible from most parts of the world (except for very northerly or southerly regions), and can sometimes be seen during the day if conditions are right.   The Science of Sirius The astronomer Edmond Halley observed Sirius in 1718 and determined its proper motion (that is, its actual motion through space). More than a century later, astronomer William Huggins measured the  actual velocity  of Sirius by taking a spectrum of its light, which revealed data about its speed. Further measurements showed that this star is actually moving toward the Sun at a velocity of about 7.6 kilometers per second.   Astronomers long suspected that Sirius might have a companion star. It would be hard to spot since Sirius itself is so bright. But, they kept looking for it. In 1844, F.W. Bessel used analysis of its motion to determine that Sirius really did have a companion. That discovery was finally confirmed by telescope observations in 1862. The companion is called Sirius B, and it is the first white dwarf  (an aged type of star) with a spectrum to show a gravitational redshift as predicted by the general theory of relativity.   There are stories floating around that some early civilizations saw this companion without the aid of a telescope. It would have been very hard to see unless the companion was very bright. So, its not clear what the ancients saw. However, current scientists are quite interested in learning more about Sirius A and B. More recent observations with Hubble Space Telescope have measured both of the stars, and revealed that Sirius B is only about the size of Earth, but has the mass close to that of the Sun.   Comparing Sirius Itself to the Sun Sirius A, which is what we see with the naked eye, is about twice as massive as our Sun. It is also 25 times more luminous than our star. Over time, and as it gets closer to the solar system in the far distant fugure, it will also increase in brightness. Thats part of its evolutionary path.  While our Sun is about 4.5 billion years old, Sirius A and B are thought to be no more than 300 million years old and so their story is yet to be told. Why is Sirius Called the Dog Star?   This star has earned the name Dog Star from an interesting time in Earths past. One reason its called that is that its the brightest star in Canis Major. However, theres a more interesting idea about its name: it was also incredibly important to stargazers in the ancient world for its prediction of seasonal change. For example, in the time of the Pharoahs in Egypt, people watched for Sirius to rise just before the Sun did. That marked the season when the Nile would flood, and bathe the nearby farms with mineral-rich silt.  The Egyptians made a ritual of looking for Sirius at the right time—it was that important to their society. The rumor goes that this time of year, typically late summer, came to be known as the Dog Days of summer, particularly in Greece, when people began looking for the Dog star just before sunrise. The Egyptians and Greeks werent the only ones interested in this star. Ocean-going explorers also used it as a celestial marker, helping them navigate around the worlds seas. For example, to the Polynesians, who have been accomplished navigators for centuries, Sirius was known as Aa and it was part of a complex set of navigational star lines the islanders used to voyage up and down the Pacific between Tahitian islands and Hawaii.   Today, Sirius is a favorite of stargazers, and enjoys many mentions in science fiction, song titles, and literature. It appears to twinkle madly, although thats really a function of its light passing through Earths atmosphere, particularly when the star is low on the horizon.      Edited and updated by Carolyn Collins Petersen.

Naturalistic Observation - 1075 Words

NATURALISTIC OBSERVATION Naturalistic Observation St. Paul’s School of Nursing It’s Saturday afternoon and I am sitting here in a very crowded food court at the Staten Island mall. I will be observing a young boy about the age of 3 and I will name him Chris. Chris is sitting with his mom and with them is another little boy who seems about the same age as Chris and I assume the other woman is his mom. Chris is the most adorable looking boy with dark black hair and big dark eyes. He is sitting next to his mom and the other boy is sitting right across from him. I’m assuming that this is a play date†¦show more content†¦I caught his mom wink at the other mom as if to show victory. That’s always a great feeling in my perspective. , I then noticed that Chris was trying to tie his shoelace. His mom grabbed his foot and started to tie it for him. Chris quickly pulled his foot back and said, â€Å"No, I do it!† She allowed him to, but he was definitely struggling with it and wasn’t giving up. This shows that Chris was in Er ick Erickson’s stage called initiative-versus-guilt stage. This is where children face conflicts between the desire to act independently of their parents and the guilt that comes if they don’t succeed. . (Feldman, R. S. 2009, Page 179). Even though he was struggling, his mom did give him time to try. Erickson states that parents who react positively can help their children resolve these opposing feelings. By providing their children with opportunities to act self-reliantly, parents can support their children’s initiative. On the other hand, parents who discourage their children’s independence may contribute to a sense of guilt that persists throughout their lives and affects their self-concept. . (Feldman, R. S. 2009, Page 179). Eventually, Chris stuck his foot out to his mom so she can tie it for him. After a few minutes, Chris’ mom stood up and was putting on her jacket. Chris immediately turned to her and asked, â€Å"We go home now?† As she nodded a yes to him, he quickly began to put on his jacket. This is characteristic toShow MoreRelatedNaturalistic Observations Of Naturalistic Observation1765 Words   |  8 PagesWhat is naturalistic observation? How does a researcher collect data when conducting naturalistic observation research? Naturalistic observation gathers data to provide a â€Å"complete and accurate picture of what occurs in a setting,† (Cozby Bates, 2014, P. 119). The observation describes qualitatively events such as how people make decisions and how they solve problems using the skills individually and sometimes as a group think (Cozby Bates, 2014). Naturalistic observations take place in aRead MoreEssay on Naturalistic Observation1165 Words   |  5 Pagesorganized below by the extent to which an experimenter intrudes upon or controls the environment. 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I chose them as my observation location because those are the places where people normally talk, study, socialize and interact in a casual manner. Woman Woman The first pair I observed is woman and woman. It was in the Starbucks, two Korean women around 19 years old are standing on the line to buy coffee. Neither of them were talking on the cell phone and the one in the front

Physical Characteristics of a Spherical Lens -myassignmenthelp.com

Question: Discuss about thePhysical Characteristics of a Spherical Lens. Answer: Describe the physical characteristics of a spherical lens? Spherical lenses are classified as either concave or convex due to the curving of their spherical surfaces. Convex lenses are thick at the middle and thin at the edges. When light passes through the convex lens, it converges thus referred to as a converging lens. Concave lenses are thin at the middle and thick at the edges. Concave lenses diverge light passing through it thus are diverging lenses. Describe the physical characteristics of a toric lens and state the names given to the principal meridians on the back surface? Combines a spherical curve and cylindrical curve thus referred to as spherocylindrical Base curve - a principal meridian on the back surface with a minimum curvature What is the difference in the focus produced by a spherical and toric lenses? In a spherical lens, parallel light rays diverge from a singular focal point in concave lenses and converge in a singular focal point in convex lenses while in toric lenses, focus is at different focal points from different meridians How can you improve the field of view for hypermetropic patients? Patients who have a long sightedness disorder are referred to as hypermetropic patients or rather suffer from hypermetropia. This means, when parallel light rays pass through their eyes, objects are focused beyond their eye's retina. First, troubleshoot clinically the level of hypermetropia in order to give the right prescription. Some stages may require a prescription of spectacles with convex lenses so that focus of rays is on the retina or contact lenses prescription to eliminate prismatic effects. Other advanced stages may require surgical procedures but consult with the patient further if a surgical procedure is the only method that will improve their field of view. Describe two methods of reducing the finished centre and edge thickness of a pair of spectacles? Flattening the lenss base curve Using aspheric lens designs that generally use small sizes of spectacle frames, therefore, reducing the edge thickness of the spectacles What does minus cylinder form mean how is it used in lens design? Minus cylinder is a notation used to describe the cylinder power for the few diopters whose divergence is greater than the sphere component. The plus cylinder and minus cylinder differ by way of the different shapes produced for the ophthalmic lens used in managing the thickness and frame fitness during the lens design. Therefore, in lens design, a minus cylinder is used to manage the thickness of a lens and fitness of a lens into the frame. Polarization and polarized lenses: How are polarized lenses manufactured and how does this differ from non-polarized tinted lenses? Manufacture of polarized lenses involves stretching a material made of needle-like crystals of herapathite and a transparent polymer film of nitrocellulose, through the application of magnetic or electric fields to make the material dichroic. Polarized lenses and non-polarized tinted lenses differ by way of how they work in protecting an individual if worn as sunglasses. Polarized lenses for instance protect an individuals eyes from the suns UV rays as well as reflections and glares that cause irritation. On the other hand, non-polarized tinted lenses used in sunglasses do not offer UV protection and instead block sunlight from above in gradient tinted lenses or everywhere if they are double gradient tinted. Explain how sunlight from the environment is polarized? The Rayleigh sky model explains how sunlight from the environment is polarized by a way of a celestial pattern consisting of molecules from air, aerosols, water and dust and geometrically represented by a celestial triangle with Zenith, The sun and the scattering point of the sun rays as the apices. The pattern depends solely on the position of the sun in the solar system. Rays of light are maximally polarized at a circular band in an angle of 90 degrees from its source which is the sun and as the earth rotates around the sun, the degree of sunlight polarization changes too. (Ropars, Lakshminarayanan, Le Floch, 2014). How do polarized sunglasses lenses filter plane polarized light? When plane-polarized light passes through the polarized lenses of the sunglasses, the light waves vibrating parallel and horizontally from the source of light travel in a traverse form and enter the sunglasses. The lenses filter the waves by blocking red light which causes glares and allows blue light which is less glaring. This gives way to blue light waves vibrating vertically from the source of light What is the advantage of filtering polarized light? When used in cameras for photography purposes, filtering polarized light leads to the production of an image with increased image contrast by reducing the glare. Reflections on high minus lenses are reduced by an anti-reflective coating. Explain how the antireflective coating does this? Lenses with anti-reflective coating are manufactured using an oxide coat which blocks light reflections which would otherwise cause glares, halos and reflections around light. High minus lenses with anti-reflective coating when hit with light, the reflections made usually look like rings which make the lenses appear thick thus reducing external and internal reflections of light. List the troubleshooting steps for a progressive lens wearer complaining of a narrow reading range and distorted peripheral vision? Take a square mirror about 7 inches square and make a dot at the center of the mirror using a marking pen Place the mirror between you and the patient on the dispensing table so that it is at the patients working distance. Place all necessary markings on the PAL lenses. Make a good adjustment after putting them back to the patient. With his head straight and a reading position, let the patient take a look at the marked dot made on the mirror Look back and forth into the mirror and the patient as they look at the dot. Observe if the patient is looking via the point circle or otherwise. The highest probability is they are not. With great care, mark with the use of the marking pen on the lenses where the patient is looking so that you can make PD requirements. (Bentley, Trevaskis, Woods, Guest, Watt, 2017). The mirror test is a useful diagnostic tool for progressive lenses. Describe the process of using it including the equipment needed? Using a square mirror that is about 7 square inches, make a dot at the center of the mirror using a marking pen Place the mirror between you and the patient on the dispensing table so that it is at the patients working distance. Place all necessary markings on the PAL lenses. Make a good adjustment after putting them back to the patient. With the patients head straight and at a reading position, ask them to take a look at the mirrors marked dot. Look back and forth into the mirror and the patient as they look at the dot. Observe if the patient is looking via the point circle or otherwise. The highest probability is the patient is not looking through the near point circle Carefully mark using the marking pen on the lenses where the patient is looking in order for you to make PD requirements. The requirements for this procedure is a mirror, lenses for making new markings on, and a marking pen. (Bentley, Trevaskis, Woods, Guest, Watt, 2017). Explain why it is considered more accurate than just checking the mono distance PDs for near vision alignment? The ophthalmologist has the ability to make keen observations of the eye and thereafter make conclusive PD requirements that totally minimize the margin of error if they use the mirror test. This is in contrast to the mono distance PD for near vision alignment whose margin of error is higher. This is because the ophthalmologist is neither able to observe the pupil directions nor the position of light on the pupil. The significant advantage of aspheric lenses Aspheric lenses eliminate unwanted magnification appearance that is common in the conventional spherical lenses used by hypermetropic patients. Among myopic patients, aspheric lenses eliminate minification, which is the converse of the magnification appearance of spherical lenses used by hypermetropic patients. What measurements must be taken when dispensing aspheric lenses and why is this necessary? A dispenser records all information provided by the lens manufacturer just in case the lens has to be remade in the occasion that problems arise. To avoid the off-axis power errors that are mainly caused by improper fitting, the ray of the optical axis has to go via the eyes center of rotation. This should be done by the dispenser placing the optical axis on the surface of the aspheric lens. Therefore, in every 2 degrees of pantoscopic tilt, there should be a 1mm drop in the lens whereby the optical centers of the lenses are placed vertically and horizontally but in a monocular way. A 5-year-old child requires spectacles. Their Rx is +4.00DS R L. No patching is required. Explain some of the difficulties you may face in meeting the needs of the child taking into account their wants as well as those of the parent? The parents may have the unfounded belief that wearing spectacles weakens eyes. This may be as a result of past experiences of friends or relatives who had complained after having a spectacles prescription from quacks or unexperienced ophthalmologists and optometrists. This should be a greater cause of alarm for the parents since reading spectacles prescription for a 5-year-old is quite rare, unless the child is myopic or hypermetropic. Studies have also shown that Chinese children have this belief too, that wearing spectacles contribute to the weakening of eyes. Care, therefore, has to be taken in order not to prescribe erred spectacles which lead to ocular disorders The child may complain of the weight of the spectacles. Even though the weight of spectacles is usually negligible, for a 5-year-old child, the weight might be overwhelming. However, they should adapt to wearing the spectacles after a while. The choice of the frame that the child or the parents may prefer prior to visiting the clinic may not be available. Since dissatisfaction is one of the leading causes for the negative attitude towards a certain type of spectacles prescribed, it is important to meet their needs by giving them a future date of when to collect their preferred spectacles with the specified frame of choice. The child may prefer spectacles that are beyond the cost that the parents are able to meet. Since children cant understand cost setbacks the parents are incurring, it would be very hard convincing the child to choose another cheaper type. What lens and frame choice will be suitable for the child given that they are only 5 years of age? The spectacles need to have a small frame in order for the lens thickness too to be as small as possible. Lens that are less thick tends to reduce the risk of peripheral vision that is blurred or distorted. Plastic frames have for long been the most suitable frames for children due to the fact that they are more durable than their metal counterparts. Plastic frames with spring hinges would be more advantageous as they reduce regularly adjustments that would be made as children are not very careful with spectacles. Given that the child will be reviewed every 12 months by the ophthalmologist, why is it necessary to remake the spectacles even if the Rx doesnt change? The pupillary distance will have changed since the child will be growing up, therefore, the need to remake the spectacles. If not corrected or remade, the spectacles would be sliding down their nose as they would not be fitting well with the childs developing nose. Due to the playful nature of children at this age, the lens may have scratches or the frame lose due to cracks, therefore the need to remake the spectacles if repairs and adjustments are not possible for the old spectacles. References Ropars, G., Lakshminarayanan, V., Le Floch, A. (2014). The sunstone and polarised skylight: ancient Viking navigational tools? Contemporary Physics, 55(4), 302-317. Bentley, S. A., Trevaskis, J. E., Woods, C. A., Guest, D., Watt, K. G. (2017). Impact of supervised student optometry consultations on the patient experience. Clinical and Experimental Optometry.

Comm Arts Essay Example For Students

Comm Arts Essay Underline the independent clause and double underline the dependent clause in each given sentence. (20 pats. ) finished reading the book that you loaned me. Our trip to Holland ended with a visit to the town where my parents were born. Before the day was over, made plans to see De. Because it was raining, we dies not go to the lake. Mr Bumble winks as if he knew a secret. Susan planned to remain in the country until he visa expires. The Peterson have lived in Seattle since was young. Driving a car is illegal it you dont have a license. Fred laughed until he gasped for breath, Fresh strawberries have a luscious taste when they are ripe. V. Identify the kind of the given sentences according to their structure. (10 pats. ) 1. Matthew had always wanted a dog of his own. One day he went to an animal shelter that offered all kinds of dogs for adoption 3. As he entered, Matthew his parents asking if he was sure that he had time in his busy schedule for a dog. 4. Matthew put the question out of his mind; he was intent on picking out a dog. Matthew finally chose a small brown bundle Of fluff With sparkling eyes and a gagging tail. . In the weeks that followed, Matthew sometimes felt that days were too short to do all that had to be done, but somehow he managed. Carefully. 7. He found that he needed to organize his time 8. He kept his grades up, played soccer, and wrote article for the school newspaper. 9. Giving the puppy plenty of water, food, exercise, and attention too time, but every minute was well spent.