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Shamim Ansary:
How Many Different Types of Precious Gems Are There On Earth?

Gems are valuable, but some are much more valuable than others.

Such gems as topaz, aquamarine, and garnet are called semi-precious, and cost much less than precious gems.

There are only four minerals that are considered precious gems today: diamond, emerald, and two forms of corundum, ruby and sapphire.

Pearl, which is not a mineral but the product of oysters, is also called a precious gem.

Shamim Ansary:
When Was the Hubble Space Telescope Launched Into Orbit and Who Is the Hubble Telescope Named After?

Fortunately, NASA made plans for repairing the Hubble Space Telescope throughout its projected 15-year orbit.

Two months after the Hubble Space Telescope’s launch in 1990, it was discovered that the primary mirror had not been ground properly, among other problems.

The telescope could not be focused.

While this was a major embarrassment, the dangerous and complex repair mission was a coup.

The space shuttle Endeavor was launched in December 1993.

Its crew captured the Hubble Space Telescope, fixed it, and released it successfully.

The images and data returned since have more than outweighed the early difficulties, promising that the Hubble Space Telescope will be remembered for its scientific achievements rather than its flaws.

Many Hubble observations have led to breakthroughs in astrophysics, such as accurately determining the rate of expansion of the universe.

The Hubble Space Telescope is named after the astronomer Edwin Hubble.

Shamim Ansary:
What Does the Word “Clock” Mean In French and Where Did the Word for a Large Timepiece Come From?

Like cloche in French, the word clock literally means bell.

When the large mechanical clock was invented in the fourteenth century it didn’t tell time with a face and hands, but rather by sounding bells on the hour and eventually the quarter and half-hour.

This time device was named a clock because it told time by sounding bells.

O’clock, as in twelve o’clock or five o’clock, is an abbreviation for “of the clock,” or “of the bells.”

The word clock today is used for a large timepiece.

Shamim Ansary:
Who Invented the Zodiac, What Does Zodiac Mean In Greek, and Where Did the Zodiac Signs Come From?

The zodiacal signs originate in Babylonian astronomy during Neo-Babylonian times around 7th century BC.

The real sky that the zodiac corresponds to is simply those constellations through which the sun appears to move during the course of the year as seen from the earth.

People living anywhere on the surface of the earth would pretty much see the sun take the same path in the sky relative to these stars.

The constellations that make up the zodiac are on a plane that can be seen in both hemispheres.

The orientation is different, but the stars are in the same positions relative to each other.

Ancient thinkers observing the changing positions of the stars that accompanied the changes in seasons developed the idea of the zodiac more than two thousand years ago.

They divided the sky into twelve equal sections, or signs.

Later astrologers came to believe that the position of the stars at the time of birth influences people’s lives.

Dividing the sky according to the zodiac is of little scientific use to astronomers.

The position of the earth in space has changed since ancient times, so the dates for each sign of the zodiac no longer represent the time when the sun is in the related constellation.

The word zodiac comes from the Latin word “zōdiacus”, which comes from the Greek word “ζῳδιακὸς κύκλος”, which means circle of animals.

Shamim Ansary:
How Does an Oyster Make a Pearl?

How Does an Oyster Make a Pearl?

The inside shells of oysters and other shell-forming mollusks are covered with a shiny, lustrous substance called nacre, or mother-of-pearl. Only tropical sea pearl oysters have the beautifully colored nacre necessary to make valuable pearls. Other edible clams and oysters also make pearls. But we would not recognize them as pearls, and they have no value.

When a foreign particle such as a piece of sand or a parasite enters the oyster’s shell, these nacre-producing cells set to work, covering the particle with layer upon layer of the nacre substance, until the particle is completely enclosed.

The color of the pearl will be the same as the nacre lining of the shell. That is why there are black (really a dark gray), pink, cream-colored, and white pearls.

It takes a pearl-producing oyster about seven years to make a moderate-sized pearl!

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