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Spaceship Earth: We Are Interstellar Travelers

ASTRONOMY

Spaceship Earth: We Are Interstellar Travelers

OCT 14, 2013 03:25 PM ET // BY MARK THOMPSON

NASA astronaut Karen Nyberg took this photograph of the sun approaching sunset from the International Space Station in August 2013.

NASA/KAREN NYBERG

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 Measuring velocity is a tricky thing to do -- more so if you are trying to measure the speed of a planet upon which you are observing from. But, through careful observations by astronomers through history, it has been possible to measure the Earth's orbital velocity around the sun. Or planet is rattling around interplanetary space at a colossal speed of 107,300 kilometers (66,700 miles) per hour!

Now, taking into account the movement of the sun (with all the planets of the solar system in tow) around our galaxy's core (which is approximately 20,000 light-years distant), we are traveling at around 900,000 kilometers (560,000 miles) per hour. This is a not-so-subtle reminder that we live on a planet hurtling through interplanetary space, orbiting a star that zooms throughinterstellar space, taking 225 to 250 million Earth-years to complete one orbit of the Milky Way.

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A more obvious hint of our planetary motion is that of the rotation of our planet around its axis -- the sun rises in the east and sets in the west, and the stars slowly track across the sky. One day is 24 hours long and our clocks are based on the fact that it takes 24 hours for one whole rotation. However, this is an 'estimate' since it takes 23 hours, 56 minutes and 4 seconds for our planet to rotate once.

There are other inaccuracies that affect our everyday lives. The orbital period of our planet is actually 365.25 days, which gives us one year, but we use 365 days on our calendars. To correct for this quarter-day addition each year we stick an extra day on the calendar in February every four years -- this is known as a "leap year." There are extra criteria if the year is a "century year" butonly if it is also divisible by 400. (We do make things complicated for ourselves.)

As Earth travels around the sun, the distance between the two bodies changes from the closest at 147 million kilometers (91 million miles) -- known as "perihelion" -- in January to the most distant at 152 million kilometers (94 million miles) -- "aphelion" -- in July. Surprisingly perhaps, this change in proximity is not the cause of the seasons we experience. Instead, it is the tilt of the Earth’s axis of rotation, which means the Northern Hemisphere experiences summer when it is pointing toward the sun while the Southern Hemisphere is in the depths of winter.

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The Earth interacts with its surroundings as it hurtles around the solar system and this can be beautifully demonstrated by the beauty of meteor showers.

The showers of "shooting stars" are actually debris from comets shed along their orbit as they orbit the sun. As Earth plows through these debris clouds, the tiny pieces of dust burn up in the atmosphere, heating up the surrounding air and ablating, lighting up the sky as they descend. Earth passes through the orbit of the comets at the same time each year producing 20 or so popular meteor showers.

It is not just meteor showers that we can observe from our planetary "spaceship" as we travel around the sun. Aurorae at high latitudes in the Northern and Southern Hemispheres generate beautiful light shows as the aurora borealis and aurora australis, respectively.

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Aurorae are caused by the interaction of the Earth's upper atmosphere and solar plasma. We know the sun kicks out a lot of energy, but it also generates the solar wind that is composed of charged particles that travel at speeds in excess of 400 kilometers (250 miles) per second. When they hit Earth they cause the gas in our atmosphere to glow in a similar way electricity causes fluorescent tubes to glow.

During our busy lives, it can be easy to think that we are cocooned in a large bubble called Earth, with the universe rotating around us, when in fact it is us who are blasting through space, interacting with the interplanetary medium. Instead, if you look around you, there is plentiful evidence that we are actually passengers journeying through the solar system and the Milky Way. On even larger scales, our galaxy and the Andromeda Galaxy are barreling toward one another at a rate of 400,000 kilometers (250,000 miles) per hour.

It is this movement, this trip on board a spaceship that we call Earth,that grants us the beautifully changing sights in the night sky.

http://news.discovery.com/space/astronomy/spaceship-earth-we-are-interstellar-travelers-131014.htm?__utma=17607724.790739733.1381921554.1381921554.1381921554.1&__utmb=17607724.1.10.1381921554&__utmc=17607724&__utmx=-&__utmz=17607724.1381921554.1.1.utmcsr=google|utmccn=(organic)|utmcmd=organic|utmctr=(not%20provided)&__utmv=-&__utmk=87032920

SOPA DE LETRAS

T	D	F	A	S	T	A	R	S	A
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R	T	A	M	O	E	W	E	E	K
R	M	R	O	O	R	K	A	M	F
A	O	H	S	T	R	B	W	O	E
M	S	T	P	I	S	H	I	C	S
O	P	J	H	N	O	Y	H	T	J
A	H	O	E	G	A	L	A	X	Y
N	E	T	R	A	M	S	L	K	H
G	R	E	E	S	Y	K	S	L	W

Earth, shooting stars, atmosphere, comets, orbit, galaxy

Responde

1-¿De qué se trata el texto?

2-¿A qué velocidad aproximadamente se mueve nuestro planeta?

3-¿Cuál es el indicio más fehaciente de que nuestro planeta se mueve?

4-¿Cuántas horas tiene un día?

5-¿Cuántos días tiene un año?

6-¿Qué son las lluvias de estrellas?

7-¿Cómo se producen las auroras?

1-Del movimiento de la Tierra

2-107,300 kilometros (66,700 millas) por hora

3-El movimiento de Rotación

4-23 horas, 56 minutos y 4 segundos

5-365,25 días

6-Las lluvias de "estrellas fugaces" son restos de cometas arrojados a lo largo de una órbita.

7-Las auroras son causadas por la interacción de la atmósfera superior de la Tierra y el plasma solar

Dentilin/Salud bucal

Eight Steps to Dental Health

It takes more than just brushing. 
OK, so you know about brushing and flossing. But there are other steps you should take if you want to keep your teeth for a lifetime. Some people assume they will lose their teeth as they age. That doesn't have to happen. David A. Albert, D.D.S., M.P.H., suggests these steps to keep your teeth and your mouth healthy. Dr. Albert is an associate professor of clinical dentistry at the Columbia University College of Dental Medicine.

Step 1: Understand your own oral health needs. 

"Your oral health depends on many factors," Dr. Albert said. "These include what you eat, the type and amount of saliva in your mouth, your habits, your overall health and your oral hygiene routine."

Changes in your overall health status often result in changes in your oral health. "For example, many medicines, including more than 300 common drugs, can reduce the amount of saliva in your mouth, resulting in dry mouth," he said.

"Women who are pregnant go through oral changes. This often includes inflammation of the gums, which is called pregnancy gingivitis. Patients with asthma often breathe through their mouths, particularly when sleeping. This can result in dry mouth and increased plaque formation and gingivitis."

Step 2: Commit to a daily oral health routine. 

Talk to your dentist or dental hygienist about your oral health practices. Based on the discussion, come up with an effective routine. It should be easy to follow and should take your situation into account. For example, if you are taking medicine that dries your mouth, it is important to use fluorides every day. Fluorides can be prescribed for home use. They come in several forms — rinses, toothpastes and gels. The gels are either brushed on or applied using a tray. Pregnant women, people with health conditions such as diabetes, and people with braces also need special daily oral health care.

Step 3: Use fluoride products. 

Everyone can benefit from fluoride, not just children. Fluoride strengthens developing teeth in children. It also helps prevent decay in adults and children. Toothpastes and mouthwashes are good sources of fluoride. Your dentist can prescribe a stronger concentration of fluoride in a gel, toothpaste or rinse if you need it.

Step 4: Brush and floss to remove plaque. 

Everyone should brush at least twice a day. It's even better to brush three times a day or after every meal. In addition, you should floss at least once a day. These activities remove plaque, which is a complex mass of bacteria that constantly forms on your teeth. If plaque isn't removed every day, it can turn the sugars found in most foods and drinks into acids that lead to decay. Bacteria in plaque also cause gingivitis and other periodontal diseases. It's important to brush and floss correctly and thoroughly. You need to remove plaque from all sides of the tooth and where the tooth meets the gums. If plaque is not removed, it can lead to gum problems and cavities.

Step 5: Limit snacks, particularly those high in simple sugars, and eat a balanced diet. 

Every time you eat, bits of food become lodged in and around your teeth. This food provides fuel for the bacteria in plaque. The bacteria produce acid. Each time you eat food containing sugars or starches (complex sugars), your teeth are exposed to these acids for 20 minutes or more. This occurs more often if you eat snacks and the food stays on your teeth for a while. These repeated acid attacks can break down the enamelsurface of your teeth, leading to a cavity. If you must snack, brush your teeth or chew sugarless gum afterward.

A balanced diet is also important. Not getting enough minerals and vitamins can affect your oral health, as well as your general health.

Step 6: If you use tobacco in any form, quit. 

Smoking or using smokeless tobacco increases your risk of oral cancer, gingivitis,periodontitis and tooth decay. Using tobacco also contributes to bad breath and stains on your teeth.

Step 7: Examine your mouth regularly. 

Even if you visit your dentist regularly, you are in the best position to notice changes in your mouth. Your dentist and dental hygienist see you only a few times a year, but you can examine your mouth weekly to look for changes that might be of concern. Changes in your mouth that you should look for include:

·         Swollen gums

·         Chipped teeth

·         Discolored teeth

·         Sores or lesions on your gums, cheeks or tongue

A regular examination is particularly important for tobacco users, who are at increased risk of developing oral cancer. If you smoke or use smokeless tobacco, your dentist or dental hygienist can show you where a sore, spot, patch or lump is most likely to appear.

Step 8: Visit the dental office regularly. 

Talk to your dentist about how often you should visit. If you have a history of cavities or crown and bridge work, or are wearing braces, you should visit the dentist more often. Some people, such as diabetics or smokers, have more gum disease than the general population. They also should visit the dentist more often. People with suppressed immune systems also are more likely to have dental problems. Examples include people who are infected with HIV or are receiving cancer treatment. More frequent visits for these groups are important to maintain good oral health.

©2002-2013 Aetna, Inc. All rights reserved.

4/29/2011

Bibliography:

http://www.colgate.com/app/CP/US/EN/OC/Information/Articles/Oral-and-Dental-Health-Basics/Oral-Hygiene/Oral-Hygiene-Basics/article/Eight-Steps-to-Dental-Health.cvsp

  

ACTIVIDADES SON RESPECTO AL TEXTO:

Indica si las siguientes oraciones son verdaderas o falsas. De ser alguna de ellas falsa argumenta.

1-    La cantidad de vitaminas y minerales ingeridas no afecta la salud bucal.

2-    Las personas que no concurren al odontólogo y poseen gingivitis son quienes tienen mayor riesgo de contraer cáncer oral.

3-    La salud oral depende de varios factores como ser: lo que se ingiere, el tipo y cantidad de saliva en la boca, hábitos, estado de salud en general y la rutina de higiene oral.

4-     Es importante el uso del flúor pero este puede perjudicar los dientes en desarrollo de los niños.

Respuestas:

1-    F. No ingerir suficiente cantidad de minerales y vitaminas puede afectar tanto la salud bucal como la general.

2-    F. Las personas con mayor riesgo de contraer cáncer oral son los consumidores de tabaco.

3-    V.

4-    F. El flúor fortalece los dientes en desarrollo de los niños.

A partir de la lectura del texto responde:

1-    ¿Quién sugiere los 8 pasos para obtener una boca sana?

2-    Según el texto para la higiene bucal es necesario la utilización del fluoruro ¿este está presente solamente en las pastas dentales?

3-    ¿Qué es la placa?

4-    Según el texto las bacterias producen ácidos a causa de los restos de alimentos en los dientes ¿Qué biomolécula orgánica participa en la formación de ácidos con mayor duración?

Respuestas:

1-    El Dr. Albert.

2-    No, puede estar presente tanto en las pastas dentales como en enjuagues y geles.

3-    Es una masa compleja de bacterias que se forma constantemente en los dientes. Dichas bacterias pueden generar variadas enfermedades.

4-    Cuando se ingieren alimentos que contienen azúcares, es decir, Carbohidratos.