Age of the universe
The age of the universe is around 13.7 billion years.
Age of the earth
The age of the earth is around 4.5 billion years.
An atom contains a nucleus at its center and electrons that "rotate" around the nucleus. The nucleus contains nucleons, that is, protons and neutrons. The electrons have a negative electrical charge. The protons have a positive electrical charge, of the same value as that of the electron.
Billion in million
A billion (1 000 000 000) = a thousand million.
At the chemistry level life is surprisingly commonplace: carbon, hydrogen, oxygen and nitrogen, a little calcium, a drop of sulfur and a light dust of other very ordinary elements.
Life on Earth is not only brief but terribly tenuous. We come from a planet that is very good at promoting life, but far better at annihilating it. The average species on Earth only lasts about 4 million years.
Our solar system is enormous
On a diagram of the solar system to scale, with the Earth reduced to the diameter of a pea, Jupiter would be over 300 metres away and Pluto would be 2.5 km distant and about the size of a bacterium.
On the same scale Proxima Centauri, our nearest star would be 16000 km away.
The average distance to the Moon is 385,000 km
The average distance between stars is over 30 million million kms
Sea salt
Sea water is salty due to the intense volcanic activity of the early ages of the Earth. A large amount of volcanic gas was then released into the hot atmosphere of the earth. Later, when the earth cooled, all this water vapor and these gases precipitated in acid rain, eroding the rocks for millennia. This water loaded with ions, minerals and alluvial deposits poured into the oceans, gradually stabilizing at the present salinity by the play of the dissolution of the salts and the evaporation of water.
A few Speeds
Speed of light:
186 000 mi/second (300 000 km/second)

The Earth rotates on its axis at a speed of about 994 mi/h (1 600 km/h)
The Earth rotates around the sun at 62 137 mi/h (100 000 km/h)
The Sun orbits around the center of the Milky Way at 528 165 mi/h (850 000 km/h)
Our galaxy sails at nearly 1 429 153 mi/h (2,3 millions de km/h), 391 mi per second (630 km/s).
Very large numbers
10 E9 = 1 000 000 000 = 1 Billion short scale (anglophones) = 1 Milliard long scale (others)
10 E12 = 1 000 000 000 000 = 1 Trillion short scale (anglophones) = 1 Billion long scale (others)
10 E15 = 1 000 000 000 000 000 = 1 Quadrillion short scale (anglophones) = 1 Billiard long scale (others)
10 E18 = 1 000 000 000 000 000 000 = 1 Quintillion short scale (anglophones) = 1 Trillion long scale (others)


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