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Khoj - Edition #1 on 11 Dec 2022

Updated: Dec 19, 2022

The bad weather did not dampen the spirits of my neighbours as they came together, both children and adults, to make the first edition of Khoj a success. Khoj is my attempt to establish a platform where people of all ages can come and discuss science and astronomy. It is a forum that gives opportunity for people to ask any question, share knowledge or debate on matters related to science and astronomy. Often seemingly simple questions open up the door for much larger and deep discussions and discoveries. That's precisely what we witnessed in this edition, as you can see from the summary below.

Summary of the first edition below:

How astronauts eat and drink if there is no gravity in space?

They use specially packed food and beverages that they will have to consume by sucking from the container. If it is let out, it starts floating. So they cannot eat as they normally do on Earth.

If there is no gravity in space how the spacecraft lands on planets and our Moon?

Actually there is gravity in space (see next question and discussion below). Any body that has matter exerts a gravitational force on other bodies (including light). Even two humans when they come close exerts gravitational force on each other, though it is too small to be experienced. So scientists calculate how much gravity a planet, asteroid or our Moon has to determine how they design the landing mechanism of spacecrafts. Japan's refrigerator sized probe Hayabuza2 that landed on the asteroid Ryugu was bounced around before it was able to land firmly because of the rather weak gravity a small asteroid like Ryugu exerts.

Are the astronauts floating in space because of lack of gravity?

Not really. There is gravity everywhere. Astronauts are constantly on a free fall towards Earth when they are inside the spacecraft or space station. In fact, even the spacecraft and spacestation orbiting Earth is constantly on a free fall towards Earth, but their constant motion around the planet that is aligned with the curvature helps them avoid crashing on to the planet. See this article for more details: What Is Microgravity?

Further discussion around the initial questions on gravity

Earth's magnetism and how we are fortunate?

Earth's solid inner core, molten outer core and solid mantle helps in generating magnetism as Earth spins. This magnetic field protects us from harmful radiation from the Sun.

This magentic field also helps turtles and other marine animals to find directions across vast featureless oceans. It also helps in birds in their migration across continents.

Turtle can travel long distances to eat sea grass from the straights between Papua New Guinea and Australia. Then they find their way to return home by aligning the iron in their brain to Earth's magnetic field.

Parked Question: How do they know there is sea grass near Australia and how they find their way to that place in the first place?

This was the winning question, winner being Aditya!

Where did all the elements that we see around come from?

Hydrogen is the most fundamental of all the elements. Universe was born with abundance of Hydrogen. The Hydrogen rich gas clouds then collapsed due to gravity to form stars and planets. Stars then started fusing Hydrogen atoms to form heavier elements. When stars die and explode, these heavier elements are thrown into space which is used in the formation of new stars and planets. See this video (suitable only for 12 years and above due to the complex topic being discussed) for more details:

What happens if Sun suddenly disappears?

Since nothing can travel faster than light, Earth will continue to revolve around a non-existent Sun for about 8 minutes before it realises that Sun's gravity is no longer existing. It will then drift off into space tangential to the current orbit.

How clouds spin?

They spin due to the spin of the planet. Various latitudes of the planet spin at different speeds due to the difference in circumference of the planet at different latitudes. Equator has a faster speed than other latitudes as the circumference of the planet is the highest there. This creates an effect known as Coriolis Force

Parked Questions:

  1. If light travels so fast across such large distance, wouldn't it ever get tired?

  2. How plants regulate their intake of water and nutrients?

  3. Why do we age and die? It is due to the decay of our cells. But why do cells decay if it is fed with nourishments?

Before you leave the page, you might be interested in reading this compilation of questions young children asked me in the past:

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