What is a light-year? Physics definitions
Light takes years to reach us from these stars far away in space. What is a light-year? A light-year is the distance that light can travel in one year - [...]
16
08, 2017
16
08, 2017
What is electricity? Physics
What is electricity? A bolt of lightning in the sky What is electricity made of? Everything in the universe is made of atoms. Those atoms are made of electricity. Atoms are [...]
27
07, 2017
Medieval Islamic astronomy
Islamic astronomers taking observations West Asian astronomy before Islam West Asian astronomers had been world leaders in astronomy for thousands of years before the Islamic conquests in the 600s AD. In the last centuries BC, [...]
18
07, 2017
What is parallax? History of astronomy
Parallax and your finger Parallax comes from the Greek word "para", meaning "alternate" and "alla", meaning "change". Greek people used the word parallax to describe how an object seems to move when [...]
18
07, 2017
Ancient Greek astronomy
Greek astronomy: Eclipse of the sun Astronomy before the Greeks The art of astronomy was already very advanced before the Greeks began to interest themselves in the stars. The Egyptians and especially [...]
16
07, 2017
What is an astrolabe? Greek science
An Islamic astrolabe (832 AD) Who invented the astrolabe? About 140 BC, the Greek astronomer Hipparchus of Rhodes invented the science of trigonometry. What's trigonometry? Greek astronomy History of astronomy All our [...]
2
06, 2017
What is metal? Chemistry
Copper ore in Iran What is metal? Metals are atoms that attach themselves to other atoms in a particular way. Metal atoms, because of how their electrons are arranged, lose [...]
2
06, 2017
What is sulphur? Atoms, elements, chemistry
Diagram of a sulphur atom Sulphur atoms fall near the middle of the scale: they are heavier than silicon but lighter than iron. Every atom of sulphur has 16 protons [...]
2
06, 2017
What is the strong nuclear force? Atoms and Physics
Diagram of an iron atom The protons inside the nucleus of an atom all have a positive electrical charge, so they push away from each other. But the strong nuclear [...]
2
06, 2017
What is silicon? Atoms, elements, chemistry
Diagram of a silicon atom When a red giant star is getting older and runs out of helium fuel, it starts to convert the oxygen atoms in the star into silicon [...]
