Written by Joey Lewitin


Travertine is one ofrepparttar most beautiful, versatile, and historically important stones. Its durability makes it highly useful in building applications, and it has been used in this manner sincerepparttar 127629 Roman Empire.

Formation Travertine is a form of limestone that is heavily compacted. Generally it is formed when minerals in streams or hot spring water become deposited on river beds and dry out. Ifrepparttar 127630 chemical composition has enough ofrepparttar 127631 mineral calcium carbonate in it, thenrepparttar 127632 result is considered to be travertine.

Coloration In its purest form travertine is a very pale color, however imperfections in its structural make up, such asrepparttar 127633 presence of iron, can cause beautifully colorful banding to occur across its face. Different colors are caused by different minerals, and different shapes are formed inrepparttar 127634 stone dependant on howrepparttar 127635 impurity combines with its structure. Sincerepparttar 127636 imperfections show up semi-randomly, no two pieces ever look exactly alike. It is however grouped into quarry names where similar strains ofrepparttar 127637 marble taken from similar places are classified into categories.

Time travel: sci-fi?

Written by Khalil A. Cassimally

When you look atrepparttar clear night sky, you see stars-those tiny diamonds suspended inrepparttar 127628 vast pitch-black emptiness. But stars shine because…? Our own sun, which is a star, emits light. Stars are like giant bulbs but are much more powerful.

Light travels at a speed of 3.0*108m/s in vacuum and space is mostly vacuum. In other words light can cover a mighty distance of 300 000 000m in only 1 second!

The thing is that 300 000 000m is a just one of those small amounts in space. Other stars are billions of kilometres-let alone metres-away. Astronomers in fact use light year asrepparttar 127629 unit for distance. One light year isrepparttar 127630 distance travelled by light (in vacuum) during one year. Therefore one light year equals (300 000 000*3600*24*365)m.

A single light year is definitely huge: 9.46 trillion kilometres-no need to put this in digit form-in fact. But where exactly do I want to converge? A star that you see inrepparttar 127631 night sky is not one but many light years away. This means that it is very far away. But most importantly, it means that light from this particular star takes many years-and not mere seconds-to reach your eyes! So what?

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