Enjoyable questions and problems

  K452b Artist Impression Image Credit NASA and Wikimedia Commons Exoplanets are Planets outside our solar system. Over four thousand of them have been discovered. They orbit some star other than the Sun. Some are earth-like. They have temperatures suitable for living things. Some exoplanets even have an atmosphere. Some have hard surface at least in part so that life can live on it. Some other exoplanets are balls of gas! Scientists have not found any proof of living things on any of these exoplanets. Who knows, they may find proof of that in the coming years. The image above is not a photograph. It was an artist’s painting. NASA used it to tell news reporters in July 2015 about how its scientists found it. We don’t know much about it yet. It may be earth-like in some respects. It is in the constellation of Cygnus, the Swan.  Do you want to go there? Even if you travel at the speed of light, it will take approximately 1,800 years! We have no clue how we can travel that ...

       Photo: Irvin calicut, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons We had a partial solar eclipse on Tuesday, October 25, 2022. Today, Tuesday, Nov 8, 2022, we had a lunar eclipse. Is it a rare coincidence? Or is it that solar and lunar eclipses occur within 14 days of each other often? If so, why? Can you think of a reason? Can someone tell you? Srinivasan Ramani  

  We had a partial solar eclipse on Tuesday, November 25, 2022. It was a new moon day. We call it a partial solar eclipse when a part of the Sun is visible while the rest is covered. Is it true that solar eclipses occur only on new moons? Why don’t they occur every new moon? Discuss this with family members. Or ask a teacher. Can you watch a solar eclipse in future? Don’t do it unless you are with someone knowledgeable about it. Looking directly at the Sun is always dangerous. They will tell you how to observe an eclipse without hurting your eye.  The next solar eclipse would be on  April 8, 2024. It would be a total solar eclipse in some countries, including the USA. During a total solar eclipse, the whole Sun would be covered by a shadow.  Even that eclipse should NOT be observed by looking directly at the Sun.  Srinivasan Ramani

This is the story of our most recent common ancestor. She is called Mitochondrial Eve. She is different from the Eve mentioned in the bible. Scientists have found a method of extracting the substance named DNA from old bones. If they find two similar skeletons, by studying the DNA, they can say which is older. They can even say how much older. They can say which is an ape skeleton and which is a human skeleton. They can also say if the older skeleton is that of an ancestor of the other one. They can collect a sample of your DNA by merely rubbing a cotton bud on your inside-cheek. That will show them which part of the world your ancestors came from! Using these methods, scientists have identified a set of bones found buried in East Africa as being approximately 155,000 years old. From the skeleton’s shape and from the DNA, they know that it is the skeleton of a woman. The amazing discovery is that she is the ancestor of every human being on earth! We all have a common ancestor! The...

  “Takes this medicine on Monday, Wednesday, Friday and Sunday”: this sentence tells you to take the medicine on - days. Tell me what word one should use instead of - here. “Don’t take this medicine. A better - is Tylenol”. Tell me what word one should use instead of - here. Srinivasan Ramani 

  There are 20 houses on the 13 th Street in a small town. 15 of these houses have a dog. 9 houses have a cat. No house is without a pet. How many houses have a dog and no cat?  Houses that have a dog = 15 Houses that havea cat =       9 Total number of houses = 20 How can the first two numbers add up to more than the number of houses? That is because some houses have a cat as well as a dog. Consider 15 + 9 - 20 = 4. So, four houses have dogs as well as cats.  How many houses have a dog and no cat? 15 - 4 = 11  Srinivasan Ramani 

  There are 20 houses on the 13 th Street in a small town. 15 of these houses have a dog. 9 houses have a cat. No house is without a pet. How many houses have a dog and no cat? (The answer will appear here on Thursday, 11 th August). Srinivasan Ramani