Eratosthenes of Cyrene c. Eratosthenes was the first person to use the word "geography" and other geographical terms that are still in use today, and his efforts to calculate the circumference of the Earth and the distance from the Earth to the Sun paved the way for our modern understanding of the cosmos.
Among his other many accomplishments were the creation of the first map of the world and the invention of an algorithm known as the sieve of Eratosthenes, which is used to identify prime numbers.
This was a major opportunity, and Eratosthenes was excited to accept the position. In addition to being a mathematician and geographer, Eratosthenes was also a very gifted philosopher, poet, astronomer, and music theorist.
He made several significant contributions to science, including the discovery that a year is slightly longer than days, requiring an extra day—or leap day—be added to the calendar every four years to keep it consistent.
While serving as the head librarian and scholar at the Library of Alexandria, Eratosthenes wrote a comprehensive treatise about the world, which he called "Geography. His map of the worldthough highly inaccurate, was the first of its kind, featuring a grid of parallels and meridians used to estimate distances between different locations.
Though Eratosthenes' original "Geography" did not survive, modern scholars know what it contained thanks to reports by Greek and Roman historians. The first book of "Geography" contained a summary of existing geographical work and Eratosthenes' speculations about the nature of the planet Earth. He believed it was a fixed globe whose changes only took place on the surface.
The second book of "Geography" described the mathematical calculations he had used to determine the circumference of the Earth. The third contained a map of the world in which the land was divided into different countries; it is one of the earliest examples of political geography. Eratosthenes' most famous contribution to science was his calculation of the circumference of the Earth, which he completed while working on the second volume of his "Geography.
After hearing about a deep well at Syene near the Tropic of Cancer and modern-day Aswan where sunlight only struck the bottom of the well on the summer solstice, Eratosthenes worked out a method by which he could calculate the circumference of the Earth using basic geometry.
Knowing that the Earth was a sphere, he needed only two critical measurements to calculate the circumference. Eratosthenes already knew the approximate distance between Syene and Alexandria, as measured by camel-powered trade caravans.
He then measured the angle of the shadow in Alexandria on the solstice. By taking the angle of the shadow 7. Remarkably, Eratosthenes determined the circumference to be 25, miles, just 99 miles over the actual circumference at the equator 24, miles. Although Eratosthenes made a few mathematical errors in his calculations, the, canceled each other out and yielded an amazingly accurate answer that still causes scientists to marvel. A few decades later, the Greek geographer Posidonius insisted that Eratosthenes' circumference was too large.
He calculated the circumference on his own and obtained a figure of 18, miles—about 7, miles too short. During the Middle Ages, most scholars accepted Eratosthenes' circumference, though Christopher Columbus used Posidonius' measurement to convince his supporters that he could quickly reach Asia by sailing west from Europe.
As we now know, this was a critical error on Columbus' part. Had he used Eratosthenes' figure instead, Columbus would have known he was not yet in Asia when he landed in the New World. A noted polymath, Eratosthenes also made notable contributions to the field of mathematics, including the invention of an algorithm used to identify prime numbers.
His method involved taking a table of whole numbers 1, 2, 3, etc. This method became known as the sieve of Eratosthenes, as it works by filtering out the non-prime numbers in the same way that a sieve filters solids out of liquids. In his old age, Eratosthenes became blind and he died of self-induced starvation in either or BCE in Alexandria, Egypt. He lived to be about 80 to 84 years old.
Eratosthenes was one of the greatest Greek polymaths, and his work influenced later innovators in fields ranging from mathematics to geography.Toggle navigation. Legislative Branch. Executive Branch. Judicial Branch. The Legislative Branch of the Government. The Executive Branch of Government.
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Civil War Battles Timeline.It is divided in half almost equally by the Equator. Africas physical geographyenvironment and resources, and human geography can be considered separately. Some of these regions cover large bands of the continent, such as the Sahara and Sahel, while others are isolated areas, such as the Ethiopian Highlands and the Great Lakes.
Each of these regions has unique animal and plant communities. Sahara The Sahara is the worlds largest hot desertcovering 8. Defining Africa's northern bulge, the Sahara makes up 25 percent of the continent.
The Sahara has a number of distinct physical features, including ergs, regs, hamadas, and oases. Erg s, which cover 20 percent of the Sahara, are sand dune s that stretch for hundreds of kilometers at heights of more than meters 1, feet. Ergs cover most of Algeria and Libya and parts of Mali and Nigeria.
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Ergs can contain large quantities of saltwhich is sold for industrial and food use. Reg s are plains of sand and gravel that make up 70 percent of the Sahara. The gravel can be black, red, or white. Regs are the remains of prehistoric seabeds and riverbeds, but are now nearly waterless. Hamada s are elevated plateau s of rock and stone that reach heights of 3, meters 11, feet.
They include the Atlas Mountains, which stretch from southwestern Morocco to northeastern Tunisia; the Tibesti Mountains of southern Libya and northern Chad; and the Ahaggar Mountains in southern Algeria. An oasis is a hub of water in the desert, often in the form of spring s, wells, or irrigation systems. About 75 percent of the Saharas population lives in oases, which make up only 2, square kilometers square miles of the deserts vast area.
The Saharas animal and plant communities have adapted to the regions extremely dry conditions. The kidney s of the jerboa, a type of rodent, produce highly concentrated urine that minimizes water loss.
A dromedary camel conserve s water by changing its body temperature so it doesn't sweat as the day gets hotter. The scorpion limits its activities to night, burrowing into the cooler sands beneath the surface during the day. The scorpion, a predatoralso absorbs water from the flesh of its prey.
Saharan plants survive thanks to root systems that plunge as far as 24 meters 80 feet underground. In parts of the Sahara, plants cannot take root at all.
Africa: countries quiz
In the southern Libyan Desert, for instance, no greenery exists for more than kilometers miles. Sahel The Sahel is a narrow band of semi- arid land that forms a transition zone between the Sahara to the north and the savannas to the south.
It is made up of flat, barren plain s that stretch roughly 5, kilometers 3, miles across Africa, from Senegal to Sudan. The Sahel contains the fertile delta of the Niger, one of Africas longest rivers. Unfortunately, the Sahels fertile land is rapidly becoming desert as a result of droughtdeforestationand intensive agriculture. This process is known as desertification. The Sahel's animal communities are constantly scavenging for scarce water and vegetation resources.
The Senegal gerbil, the most common mammal in the Sahel and measuring only a few centimeters, consumes as much as 10 percent of the Sahel's plants.Speak now. Do you know which continent is the largest, and which is the smallest, which has the highest mountain, or which one has the lowest valley?
Take our online continent quizzes to test your knowledge! Top Trending The Continent Quiz.
Sample Question. North America.Article essay differences and disorders
South America. Can you tell which type of asian someone is? Let's see if you are smart or ignorant. Countries And Continents Quiz. Continents And Oceans Quiz. Although some people have different opinions about which continent is the most diverse one — some people would claim that Africa is the most diverse continent because it has different culture. Who is continent are both a continent and a country? The continent which is also a country is letter B or Australia.
The Australian continent goes by other names such as Sahul, Meganesia and Australinea. It is different from the Australian mainland as the continent comprises of the Australian mainland. What does Continent mean? There are seven continents on Earth. A continent is a large mass of land that has been isolated or divided. Each continent contains countries. These continents be. What is one of the most interesting features of Australia?
One of the most interesting features of Australia is the Great Barrier Reef. It is composed of more than 2, individual reefs and different island. Most Popular. Find out here in this great quiz made by the Master Asian Black. Asian Rainbow. Asian Silver and Gold. Asian White. Asian Brown. Cycle Ten Continent Quiz. They wanted to help organize African schools. They wanted to solve ethnic and tribal disputes.
They were involved in the slave trade. They needed African agricultural products. This quiz will test your knowledge of our study of the continents. Choose the best answer from the options. The Australian Continent.Random Quiz. Geography Quizzes Random Geography Quiz. This is one of the coolest quizzes we've seen in some time, and all we have for you is two words.
Good luck. US States. Countries of the World. No matter how many times you guess it, Narnia is not a real country.
You have to let it go. Find the US States. Countries of Europe. In the U. Countries of Africa. Who gave Toto the power to bless the rains in Africa? Seems like there should be someone more qualified. Countries of Asia. Geography Bunker. Country Trivia Logic Puzzle. If you've played on Sporcle long enough you know there really isn't any logic to geography, but in any case, this quiz is awesome.
Countries of the World Redux. Some of you are going to be very disappointed to find that Kashyyyk is not a real country. Countries of South America. With only 12 answers, South America may be the easiest of our continent quizzes to finish. US Capitals. Countries of North America. Countries of the World - No Outlines Minefield. Can you find all of the countries of the world without any border outlines and without making a mistake?
US Cities: North to South. Countries of Oceania. If you're looking for lots of salt water and Tasmanian devils, then Oceania is the place for you! Flags of the World. Clickable Countries by Continent. It's going to be tough to get these countries in order, there's just too many people to move around. Capitals of Europe. If you have a problem with anyone in Europe, now you know where to go to see who's in charge. Find the Countries of Europe. Most Sporclers can name all 47 countries of Europe.
But do you know where they are? Erase the World. Capitals of the World Redux.Speak now. Africa is the place where humans first appeared. And with the first humans we can imagine that the first questions appeared as well. How many questions can you answer about the second biggest continent on the globe?
Do you know enough about Africa to get through all of these quizzes? Just to make it a little easier for you we prepared a couple of sample questions for you. What is the approximate size of the African continent?
What is the largest country in terms of surface in Africa? What is the country with the largest population in Africa? How many sovereign states are there in Africa?Marketing an association the virtual business association
Come with us to one of the most interesting continents and experience the real Africa by taking our quizzes. Africa is a lovely continent. Apart from being the second largest, CNN describes it as the most photogenic. Africa is popularly known for its wildlife, culture and spirituality.
Take this test and discover the African country Sample Question. Very well. More than average. Capitals Of Africa-multiple Choice. How exciting it is to memorize capital cities of different countries! This quiz focuses on African Countries and has an array of multiples to choose from. How well do you know African capital cities?
Find out below! East African Capitals And Countries. This quiz that i put together might help you remeber the names of the capital and countries of East Africa which you would have to learn when you study Africa and Asia in 7th grade. Dar es Saloom. The Nile River. The Congo River. South Africa.
The Sahara Desert. There are many reasons why African countries have trouble stabilizing their economies: civil wars and terrorism, endless corruption, lack of basic education and inadequacy of technical skills, lack of health care, poverty, geography, international ai. Why were the ancient kingdoms in western Africa so powerful?Would you like your scores to be saved so that you can track your progress? Get a Seterra membership on Patreon.
There is also a Youtube video you can use for memorization! Seterra is an entertaining and educational geography game that lets you explore the world and learn about its countries, capitals, flags, oceans, lakes and more!
You can access the Seterra online quiz site using your computer, phone, or tablet running the latest version of most web browsers, including Safari, Firefox, Chrome, and Internet Explorer. The Seterra app offers two game modes, plus high score lists to keep track of your progress.Help me write political science dissertation conclusion
Also, with the app, you can play offline! Relocation of key government offices begins in early ! The Burundi president named Gitega to be the nation's capital. Read about a few of Africa's wildest animal species! Where are the world's most unequal countries? Widespread poverty remains a real problem, especially in Africa. Find out what countries are known by more than one name.
Learn more about the political status of Western Sahara. What countries in Africa have the highest GDPs? What countries in Africa have the highest GDP per capita? Log in Log out. All The U. Print Options.
Africa: Countries - Map Quiz Game. Africa: Countries. Nickname Score Time. There are over one billion people living in the African continent. With a population of over million and growing, Nigeria is the largest of the countries.
Using this free map quiz game, you can learn about Nigeria and 54 other African countries. If you want to practice offline, download our printable maps of Africa in pdf format. Africa: Capitals. Africa: Cities.
Africa: Physical Features. Africa North Of the Equator: Countries. Africa South Of the Equator: Countries. Central Africa: Capitals. Central Africa: Countries. Eastern Africa: Capitals.
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