The sun at sunset: The sun in Greek astronomy At first the Greeks imagined that the sun was the god Helios, or Apollo, driving his chariot around and around the earth. In the morning he began driving [...]
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 [...]
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 [...]
Antikythera mechanism: a clockwork machine to calculate how the earth and the sun move around When did Hipparchus live? Hipparchus was a Greek astronomer and mathematician in the 100s BC, in the time [...]
The earth in Greek astronomy: The Greeks never saw this view of the earth from space! Gaia and the Earth Early Greeks thought of the Earth as the goddess Gaia, the mother of [...]
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 [...]
See how the degrees match up. Many hot things take up more room than the same things when they are cold. Thermometers take advantage of that to measure heat. The old-fashioned kind of [...]
Coal plant in China: causing global warming When did global warming start? Human activities probably started to affect the world's climate as early as about 10,000 BC. That's when people [...]
Charcoal history Why use charcoal? Charcoal is a certain kind of half-burnt wood. People use charcoal for fires because it burns hotter and cleaner than wood (less smoky), and more [...]
How to write 103,367 in Egyptian numbers How to write Egyptian numbers By about 3000 BC, the ancient Egyptians had ways to write down numbers. They made one vertical line [...]
