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Tag Archives: 12+

distance to the Moon [try it]

How far is the Moon? You don’t have to look up the answer in a book. You can measure it yourself, and quite easily at that. You will need an accomplice however. For this, you will need some way to record the precise location of the Moon in the sky relative to the stars in […]

parallax [try it]

How do we know how far anything is? For nearby objects, we can pace off the distance, of course, but what about places we can’t walk to? How does your brain know that that door is 10 feet away without marking it off on a ruler? Suppose you are standing at point A (see figure) […]

solar differential rotation [try it]

The Sun is giant fluid ball of gas. It is not a solid body, and it does not behave like one. In particular, it rotates at different speeds at different latitudes. The website SolarMonitor.org displays daily collections of solar images ranging from visible light photospheric images to magnetic maps to high-energy X-ray images of the […]

exponential increase [try it]

Take a chess board and some rice. Put a grain of rice on the first square, Rook’s a1. Put two grains on the next one, Knight’s b1. Keep going down the row, doubling the grains at every square (4 on Bishop’s c1, 8 on King’s d1, etc), and continue the same way for row 2, […]

yasti yantra [Q&A]

Suhas of Poornaprajna PU College asks, what is the stick machine of Bhaskaracharya? I had no idea what it was until I looked it up online. There is a nice description in a report by S. Narvekar (Astronomical Instruments of Ancient India, IFToMM 2007) that describes a stick-like device that can be used to measure […]