SIMPLE AND GENIUS 1: How The Greeks Estimated the Circumference of Earth

Eratosthenes was a liberian in Alexandria. One day he stumbled upon a curious piece where he read that you could see the bottom of a deep well in Syene at noon on the day of the summer solstice. Alexandria was only 787km away and no such phenomenon occured there. He could tell that the sun was right above the well in Syene at noon whereas Alexendria recieve it at an angle.

He noticed that if he could calculate the angle the sun hits Alexandria with, he could use trigonometry to estimate the circumfrance of Earth. He placed a stuck a stick on the ground and measured the lenght of the shadow. He plugged in the lenght of the stick and shadow in the Law of Sines and found the angle the sun shone with over Alexandria.



Since a perpendicularly placed stick would have to pass through the center of the Earth if extended, he could use Alternate Interior Angles to work out the angle the distance between the two cities would correspond to. The graph below will brush up the high school remains of geometry knowledge you have.





Finally, he could proportion the angle to the distance to calculate the circumference:

7.2 / 360 = 787 / X
X = 39350 km

St Michael of the under-equipped hikers is gone.

The North Star no longer exists!

Apparently, it has supernovaed. The north star will outshine the combined output of an entire galaxy for a brief time and then die over several weeks or months.


What the supernova?

Temperature and pressure in a star's core is so great that it triggers a continuous nuclear fusion inside the star. The star relies on this power to make up for the energy it looses in the form of light and heat. When the hydrogen source runs out, its star can no longer sustain this nuclear fusion.

When this happens, the star is incapable of maintaining its size. The force of gravity makes a star want to shrink, and the above mentioned reactions make the star want to expand. During the life span of a star these forces are balanced, so the star remains at a fixed size. However, when there is no hydrogen to fuel the reactions, gravity wins. The inner parts shrink and the outer parts are discarded into the space.

When a star has 8 times more mass than the sun like the North Star, the outer shell breaks with the catastrophic supernova explosion. So, the sun can not go supernova.



The Little Dipper just got smaller!

The reject

Pluto's name was removed from the IAU Walk of Fame in 2006.




















The definition of "planet" set by the International Astronomical Union states that in the Solar System a planet is a celestial body that:
1) is in orbit around the Sun √
2) has sufficient mass to assume hydrostatic equilibrium (a nearly round shape) √
3) has "cleared the neighbourhood" around its orbit. :(

The third clause gave Pluto the boot from the Big Boys Band.
If Pluto was larger, it would be gravitationally dominant and thus, there would be no bodies of comparable size other than its own satellites or those otherwise under its gravitational influence.

Pluto was further humiliated as "dwarf planet", which is a celestial body that fulfills only the first two conditions.

Size does matter.

designed by chris murphy