B R Sitaram Here are the answers to last month’s questions! Q 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? A. It does create a problem. If we do not do something about it, a lunar calendar will very quickly go out of step with the solar calendar. This will result in festivals that are celebrated according to the lunar calendar being held in the wrong season! This is corrected by adding an extra month (called an intercalary month) every few years, so that the lunar calendar is brought back in step with the solar calendar. In the Hindu calendar, these extra months are called “Adhik maas”; in 2018, for example, an extra month (adhik jyaishta) was added. In such years, there will be two months with same name, one with the qualification “adhik”. Q 2. A common claim on WhatsApp and Facebook is that ancient Indian Rishis knew about the existence of 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? A. To see the absurdity of the claim, all you need to do is to list out the nava gruha. They are the Sun, the Moon, Mercury, Venus, Mars, Jupiter, Saturn, Rahu and Ketu. Of these, 4 are not planets! Only the remaining 5 (Mercury to Saturn) are planets! These were known to astronomers all over, including in Babylon, Greece, China and Egypt. What we knew was exactly what every one else knew! And, please note that the Earth was not considered a planet, neither in India nor anywhere else. Q 3. What is wrong with the phrase “burning calories”? A. Calories are a unit of energy! You cannot burn a unit, anymore than you can destroy a centimetre. What you can do is to convert energy from one form (in this case, chemical energy) into other forms (work and heat). And while this requires the oxidation of glucose, it is certainly not burnt! Q 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 OK never