Sample Astronomy Paper on The Earth

The world as a flat disk balanced on the backs of four elephants, which in turn stand on the back of a giant turtle is a humoristic version of a flat earth created by the fiction writer Terry Pratchett. Amazingly, the mythical narration that the earth is a flat body holds ground even in the current era. This is even more astonishing given the fact that around 240 B.C. already the Greek mathematician Eratosthenes could prove earth’s round shape and calculate its circumference with relative accuracy. In the 19th century, English inventor Samuel Rowbotham postulated the so-called flat earth theory. The advent of the Internet and social media led to the worldwide spread of this concept, particularly on YouTube. The contents of numerous uploaded videos range from pseudo-scientific proofs to outright ridiculous conspiracy theories. These videos have high numbers of views despite the fact that ample evidence exists to prove that the earth is a sphere.

However, our planet is not a perfect sphere. Isaac Newton was the first scientist to suggest that the earth is “an oblate spheroid, a sphere that is squashed at its poles and swollen at the equator” (Choi). Newton’s conclusion was confirmed in recent times. With satellites available and applying new methods like satellite laser ranging or using Global Positioning System receivers all over the world scientists can now determine the exact shape of the earth (Choi). The findings reveal that planet earth bulges out around the equator although only at a minimal percentage of its overall size.

Besides the sophisticated technology to measure earth’s shape accurately to the millimeter, other proofs exist to determine the spherical shape. First in line are photos that NASA makes available online, but even plain logical reasoning can prove the flat earth theory wrong. An elevated position gives an extended field of vision; a ship approaching the coast first shows its top parts before the hull becomes visible. This can only be explained by a round surface of the earth (Schlottlender 3, 10).

Parents and teachers face a problem when inquisitive children ask questions about the earth and why it is a sphere. ‘Why do people on the other side not fall off?’ could be such a question.  The only possible answer in such a case is a demonstration of gravity. An object released from the hand will fall to the ground. The same object will also fall a when released few meters away. A thought experiment can follow this demonstration with the question ‘Will the object also fall to the ground much further away, in another city, another country, or another continent?’

This experiment can introduce the word gravity to children but it cannot shed light on the question[A1]  what causes the earth to be spherical. The answer to this lies in basic laws of physics that describe how mass and gravity are interrelated with gravity being an inherent force of mass focused in the center of objects. Science reveals that even the tiniest object has mass and therefore a tiny gravitational pull although too insignificant to be noticed without sensitive laboratory equipment. In general, the force of gravity becomes stronger with the increase of the mass of objects.

The properties of mass and gravity explain why smaller celestial objects such as asteroids have irregular shapes. They do not have enough mass to overcome the resistance of their rocky and metallic materials to pull them into an efficient spherical shape. However, massive objects with millions or trillions of tons of mass exert a huge gravitational pull that creates an effective shape, that of a sphere (Cain, Why Is Earth Round).

A look at the formation of solar systems is necessary to understand how such massive objects that become planets or moons are created. It begins with a collapsing cloud of gas and dust. Gravity compresses the cloud at its center creating immense heat and ultimately a new star like our sun. The collapse creates motion and causes the cloud to spin so that it takes the shape of a disk. The areas of the disk where the centrifugal force of the spin counteracts the star’s gravitational pull are the birthplace of planets. In the outer area of the disk, large quantities of gas and ice remain and gas giants like Jupiter and Saturn or ice giants like Uranus and Neptune form. In the area closer to the star, the ice evaporates and, together with the other gases, gets absorbed by the star so that mainly rocky clumps remain. Objects different in size and mass assume different rotational speeds and paths around the star so that they inevitably collide and, over time, grow to planets or moons (Discovering Planets Beyond).

Among the four inner rocky planets of our solar system, earth is special because it has water and an atmosphere to protect life from the sun’s harmful radiation (Moskowitz). However, it has not been like this when earth was born. About 4.6 billion years ago, our planet was a red glowing ball. It cooled off after 200 million years to allow the formation of a rocky crust. The atmosphere consisted of water vapor, carbon dioxide, and ammonia (Cain, Earth’s Early Atmosphere).

Scientists believe that the earliest forms of life emerged 4 billion years ago, but it was not before the evolution of bacteria that earth’s atmosphere began to change. Cyanobacteria used sunlight for photosynthesis and released oxygen. At around 2.2 billion years ago, they had changed the atmosphere so that life as we know it today could develop.[A2] [A3] 

Evolutionary processes are counted in hundreds of millions of years. It was then only 500 million years ago that plants were the first to make the step from water to land followed by insects and then reptiles. Dinosaurs became the dominant animal species, but 65 million years ago an asteroid impact led to their extinction. This allowed mammals to evolve. The first primates appeared 10 million years later, but it took 30 more million years for apes to evolve. The oldest known fossil of a hominid is dated at 7 million years ago while Homo sapiens is, in evolutionary terms, a very young species. Our direct ancestor only came into existence 250,000 years ago (The 25 Biggest).

It seems that humankind owes its existence to the latest major catastrophe hitting our planet.

Works Cited

Cain, Fraser. ” Earth’s Early Atmosphere” Universe Today. Space And Astronomy News, 2015, Accessed 29 Nov. 2017.

Cain, Fraser. “Why Is The Earth Round?” Universe Today. Space And Astronomy News, 2017, Accessed 28 Nov. 2017.

Choi, Charles Q. “Strange but True: Earth Is Not Round.” Scientific American, 2007, Accessed 28 Nov. 2017.

“Discovering Planets Beyond: How Do Planets Form.” Hubblesite, Accessed 29 Nov. 2017.

Moskowitz, Clara. “What Makes Earth Special Compared to Other Planets.”, 8 Jul. 2008, Accessed 29 Nov. 2017.

Schottlender, Moriel. “10 Easy Ways You Can Tell For Yourself That The Earth Is Not Flat.” Popular Science, 2016, Accessed 28 Nov. 2017.

“The 25 Biggest Turning Points in Earth’s History.” BBCearth, Accessed 29 Nov. 2017.

 [A1]It is a commonly accepted truth that understanding a question is the prerequisite for delivering adequate answers, but in the 21st century the causes of spherical shape are certainly not at the heart of astronomy anymore.

 [A2]What is significant material?

 [A3]This word is not just one of those in the list of transitional expressions to be chosen at random, it has a meaning.