Daily Science+

When I was still studying in senior high, my mathematics teacher told us a love story about the French mathematician René Descartes and a Swedish Princess Kristina.

By the year 1648, when the princess is 18, Descartes was appointed to be the teacher of the young princess. Descartes taught her Cartesian coordinates system(直角坐標系), and soon they fell in love with each other. The King was furious when he learnt that his daughter was in love, and he expelled Descartes out from Sweden.

On one hand, Descartes soon felt into a serious illness, the Black Death, and could hardly recover since then. During his illness, he wrote 12 letters to Kristina, but there was no reply. Descartes died after he wrote the 13th letter to Kristina.

On the other hand, the King intercepted the letters from Descartes, and never gave them to Princess Kristina. Yet the King found the 13th letter, which only the math equation "r=a(1-sinΘ)" was written, difficult to understand. Therefore, he finally gave this letter to Kristina, hoping the letter might cheer her up a bit. At last, Princess Kristina solve the maze, and found out that Descartes was actually confessing his true heart to her.

Isn't this story beautiful? Yet we have to remember this in mind: story is often only a romantic fantasy.

In the Swedish history, by the year 1648 was the Swedish Kingdom ruled by Drottning Kristina (Queen Kristina). Though Descartes actually visited Sweden by the time, he discuss philosophy instead of mathematics. In February, 1650, Descartes contracted pneumonia(肺炎) in Sweden, and died after ten days.

Resources: Baidu Baike (百度百科)

>>The video is a speed up version of the whole process of lunar eclipse on Oct.8 .

The most exciting news for astronomy fans in Taiwan this year, might be the lunar eclipse on Oct.8, and it's the first chance for people in Taiwan to observe the lunar full eclipse since Dec.10, 2011. People can see the eclipse with naked eyes, or take photos with common photography equipment.

The reason why lunar eclipse happens, is because the moon is passing through the Earth umbra (本影). At the very beginning, the shadow will start to darken the moon gradually. And then, when the time comes, the shadow started to "cover" parts of the moon, and turn its colour to dark-red. Some might wonder why the moon doesn't vanish anyway? Since the "lunar full eclipse" means that "it's covered by Earth umbra", it doesn't means that there's no light for the moon to reflect, therefore we can still observe the moon itself.

And why is the colour "dark-red"? Actually, according to astronomers, since the moon can't reflect the sunlight directly during the lunar eclipse, the earth atmosphere will scatter the long wavelength
 light, such as blue light away, and refract the short wavelength light, such as red lights onto the moon. In addition, if the earth atmosphere is clean and clear, the colour will appeared to be brighter red; on the contrary, it will appear to be dark red, if the earth atmosphere contains more ashes and dust.

The next lunar full eclipse will be at 2015.4.4, but if people in Taiwan wish to see it without traveling far away from home, will have to wait until 2018.1.31 to see its next visit to Taiwan!

Resource: Wikipedia, 網路天文館, 中央氣象局天文訊息