Why does a hologram appear three-dimensional? To create holograms, a beam of laser light is split into two beams which travel through an arrangement of lenses and mirrors. One beam bends toward the object. The other travels toward the holographic film. Then the beams meet...
Why do cats have rough tongues? The tongues of cats, big (lions) and small, are like sandpaper. They have tough bits of flesh or papillae, which stick up from the middle of the tongue. They function like the bristles of a hairbrush. When the cat...
What is Stonehenge famous for? Stonehenge is in England and was built around 5,000 years ago. It features standing megaliths or big stones which were arranged to mark the midsummer sunrise and midwinter moonrise. It is speculated that Stonehenge might have been a religious meeting...
Which is the biggest planet? The biggest planet is Jupiter as it has more mass than the combined mass of all the other planets. It is 11 times bigger than Earth and spins 30 times faster than Earth spins. It takes a little less than...
What are star signs? From Aries to Pisces there are 12 star signs. Depending on the month and date of birth, people have different star signs. The sun, according to astrologers, moves through the stars in the heavens, during the year, passing through the 12...
Why is Uranus called the topsy-turvy planet? Planets spin around their axis while orbiting the sun. In other planets the axis is almost upright but in Uranus, the axis is at right angles to normal which makes it seem as if Uranus is lying on...
Why do people yawn? It is not just people who yawn. Even cats and dogs do. Sometimes we yawn when we are feeling sleepy or bored. It is believed that yawning makes us more alert. During yawning, the facial muscles and neck muscles are stretched....
What are yin and yang? According to Chinese beliefs, everything in nature exists in a state of harmony. The famous Chinese thinker, Confucius, used the symbols, yin and yang, to depict this. Yin is dark and yang is light. Both interlock with each other and...
Who were the Spartans? Sparta was a city state in southern Greece. It was a great military power. Spartan men had to join the army and boys had to leave home when they were seven, to get trained as soldiers. The women too had to...
Why is it difficult to breathe on high mountains? High up in the mountains, the air is thin as it has fewer molecules of gases, including oxygen which we need to live. When there is less oxygen in the air, we find it hard to...
