Why does the setting sun appear reddish-orange?

The light of the sun on the horizon takes a longer path to reach our eyes through the atmosphere. This does not happen when the sun is directly overhead. By the time the light of the setting sun reaches our eyes, most of the blue light scatters out.

The light we finally see is reddish orange. It is the color of white light minus the blue color.

Why do you cry while slicing onions?

Onion cells contain a chemical compound that contains sulfur. When we slice onions the cells rupture and react with the enzyme outside the cells.

This reaction produces molecules which react with the moisture in our eyes (forming sulfuric acid) which in turn causes an irritating sensation. This makes our eyes water.

Why do we yawn?

Yawning is an involuntary action that causes us to open our mouths wide and breathe in deeply. We yawn when oxygen levels in our lungs become low.

Studies show that during normal breathing we don’t use anywhere near lung capacity. The air sacs or alveoli needs fresh air or else they tend to stiffen up a bit.

Therefore it is believed that the brain prompts the body to either sigh or take a yawn to get more air into the lungs.

Why do flies rub their legs together?

When you see a fly rubbing its legs together, it is just cleaning itself, and scraping off some of the material that has gathered there.

But how dangerous that material may be! It may be the bacteria of such diseases as tuberculosis, typhoid fever or dysentery. Flies get such germs from garbage and sewage. If they happen to our food, the germs spread to the food, and if we eat it, we may become infected.

You may wonder how the fly carries these germs around. If you notice a fly under a magnifying glass, you would notice that the fly’s body, its claws and its padded feet, are covered with bristling hairs.

The fly’s tongue is also coated with sticky glue. This means that any place the fly stops for even a moment, it’s going to pick up things that stick to its body, its feet, or its tongue. In fact, each foot on its three pairs of legs has claws and two hairy pads-so that it can pick up plenty of things. 

Why do we laugh?

Laughter is the biological reaction of human beings to moments of humor. Depending upon the extent and pitch, laughter can be subcategorized as giggles, chuckles, guffaws etc.

Human laughter has its biological origins as a kind of shared expression of relief at the passing of danger. Laughter is a part of human behavior regulated by the brain. It provides an emotional context to our conversations. We also tend to laugh on being tickled.

The reason being that when anyone is tickled, there is an element of surprise followed by feelings of panic, laughter and sensation, which eventually breaks into peals of laughter.

Why is grass green?

The green color in grass and in most other plants, comes from chloroplast in the cells which contains four different colors. Of these, chlorophyll-a, which is blue-green in color, is the strongest.

The colors are yellow-green (chlorophyll-b), yellow (xanthophyll) and orange (carotene). The color of the grass changes from light green in early spring to dark green and brown in summer and autumn because the amount of pigment changes, like paint on a palette.

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