# Question of the Week

B R Sitaram

Here are the answers to last month’s questions!

Q 1. The great Isaac Newton was born on Christmas day 1642 and the great Galileo Galilee died on Christmas day 1642. But the two events actually took place on different days. How come?
A. When the calendar was changed from the Julian calendar to the Gregorian calendar, not all countries agreed to the change, especially countries which considered the Gregorian calendar a Popish invention. Italy changed over immediately, but England did not. There was a difference of about 11 days between the two calendars (because of the extra leap days every 100 years in the Julian calendar), which is the reason Newton’s birthday would today be reckoned as falling on 4th January, 1643.

Q 2. I have three photos taken of the night sky taken on three consecutive nights. One of the objects in the photos is a planet. How do I make out which one?
A. When you observe the night sky over a period of a few hours, you notice that the objects in the sky move from east to west. This motion of course is because of the rotation of the earth and has nothing to do with the motion of the celestial objects. When you look at stars, they move together, maintaining their relative shapes. However, planets have a separate motion of their own, relative to the stars. So, when I look at the three photos, I will see that while most of the objects will retain their positions with respect to each other, one of them, however, will move relative to the others. That’s the planet!

Q 3. Most diets are based on the idea of the calorie and talk about consuming a certain number of calories (actually kilo calories) per day. What is fundamentally wrong with this approach?
A. The number of calories is estimated by burning the food item and measuring the total heat generated. This pays no attention to whether the human body can actually digest the food or not!

Q 4. Everyone knows that Christopher Columbus was not given funds by many kings and queens till he got funds from Spain. If everyone at that time believed the earth was round, why was he denied funds?
A. No one believed his estimates of the radius (and hence circumference) of the earth! Most people were convinced that India was much further away from Europe (going westwards) than Columbus believed, and they were right!

### Questions for this month

1. Lunar calendars are based on 30 day months and 12 such months give you only 360 days. Does this create a problem? How is it solved?
2. A common claim on WhatsApp and Facebook is that the ancient Indian Rishis knew about the existence of the nine planets (Nava Gruha) for millennia, while European astronomers discovered them only after the discovery of the telescope in the 17th century. Why is this claim absurd?
3. What is wrong with the phrase “burning calories”?
4. We make it a point to make young children realize that left, right, front and back are all relative to the observer. For example, if I am standing facing you, my left is your right and vice versa. However, we rarely (if ever) talk about up and down in the same way. Are they relative or absolute? Is it okay never to talk about up and down in this way?