Tag: shine

Aluminium Used to be Costlier than Gold

By Anupum Pant

Unlike gold and silver, there is enough Aluminum in the world. It is in fact, the third most abundant element in the Earth’s crust. Also, it is about two times more abundant than Iron – an element which has a complete  branch of metallurgy revolving around it – Abundance of Aluminium is 2 times of that! Still, for the middle class of the 19th century, bricks made of Aluminium were things they could only dream to buy – Aluminium costed more than gold back then.

The same metal, Aluminium, certainly shines like silver. But our generation almost has no respect for it. Today, it is one of those blasé metals that is used to make disposable soda cans.

Back then, the US, to show off its wealth, decided to cap the Washington monument with a 3 kg pyramid of Aluminium. Later, since enterprising individuals found out a way to extract it in a very efficient manner, Aluminium became something that was not all that rare. People in the 19th century knew how precious it was. That was because, back then there was no good way to extract aluminium from its ore.

In the 19th century Napoleon III invited the King Siam to a dinner. He then gave himself Gold Cutlery, his troops Silver & the King of Siam Aluminium. This was no insult but an honour because aluminium was the most valuable metal on the planet at that time. Today, aluminium is $1,800 a ton while Gold is $50 million. – [Source]

In the mid-1800s, an Aluminum ingot would sell for about $550 per pound. Fifty years later, it costed around 25 cents for the same amount. What changed? Extraction.

Sun’s Green Flash

By Anupum Pant

More often while setting than rising, if the conditions are right, a part of the sun (on the top) can appear green. This happens for very short interval lasting for about 2-3 seconds and is considered a rare phenomenon. Since it is green and lasts for a very small interval, it is also called the green flash, emerald flash or green ray. If you have ever captured it or plan to do it in the future, do share your results with me through mail/twitter. [See the animation] [Real GIF]

What does it look like?

Sometimes the sun’s rim can appear green (in optically zoomed images). Otherwise, when the sun is set, for a brief moment, it appears as if a part of sun has separated from the main body and has turned green. It is usually seen as a horizontal line, like in the video below. But, a few lucky ones have captured complete green auras too.

Why does it happen?

The sun gives out a white light, which contains all the colors – Green is one among  them. Normally, our eye isn’t able to resolve the separate colors and sees them as a mixture which is white. When the sun sets, our atmosphere acts like a prism and bends the colors. A few colors get bent more than others. For example, green bends more than red. As a result the two colors get separated enough to be resolved by our eye. But the right amount of bending happens only if the atmospheric conditions are right.

In extremely rare cases, blue or violet flashes have been reported. [image]

For a detailed explanation you can go through this – [Geometric Optics of Green Flashes]

At poles where the sun moves in a different manner, probably the green ray can last much longer. Admiral Richard Byrd has claimed to have seen this green flash for 35 minutes while on an expedition to Antarctica.