The Study of the Universe/Space Exploration – Demo

An astrolabe illustrates how the sky looks at any given time of day and throughout the year. This is accomplished by drawing the sky (star patterns) on the astrolabe with moveable parts to adjust for the date and time. The traditional sky map astrolabe allowed people to locate celestial objects in the sky similar to how a place is located using a map. A mariner’s astrolabe is different in that it was used to measure the height or altitude of the Sun or of a star above the horizon. The altitude of a star is the angular height above the horizontal from 0 to 90°. Mariners needed to measure the altitude of the Sun or stars in the sky in order to determine their position. Knowing the altitude of the Sun at noon or of the pole star at night told them their latitude (their distance, north or south, from the equator.

The azimuth of a star is its angular position from north, measured clockwise. For example a star located directly to the north of Earth has an azimuth of 0°, while a star directly to the east has an azimuth of 90° and a star to the northwest has an azimuth of 315°.

Click here to download the demo…..

The science behind winter tires and how they work – Globe and Mail

All-season tires are a bad compromise. On snow, ice or cold pavement, the stopping distance of a car equipped with winter tires can be 30 to 40 per cent shorter than one with all-seasons. Since the force of a crash increases as the square of impact speed, this could be the difference between life and death.

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