PHYSICAL SCIENCE

• Oblate Spheroid - the shape of the earth
• Solstice - either the two times in the year, the summer solstice and winter solstice, when the sun reaches its highest or lowest point in the sky at noon, marked by the longest and shortest days
• Eclipse - an obscuring of the light from one celestial body by the passage of another between it and the observer or between its and its source of illumination
• Heliocentrism - the astronomical model in which the earth and planets revolve around the sun.
• Geocentrism - any theory of the structure of the solar system in which earth is assumed to be at the center of it all
• PYTHAGORAS believed that the earth was round and proposed a spherical theory around 500 BC.
• Anaxagoras further supported Pythagoras's proposal through his observation of the shadow that the earth cast on the moon during a lunar eclipse around 500-428 BC.
• Aristotle, a student of Plato and tutor of Alexander the Great, listed several arguments for a spherical earth which included the positions of the north star, the shape of the moon and the sun, and the disappearance of the ships when they sail over the horizon around 384-322 BC.
• Eratosthenes made the first successful attempt to determine the size of the earth by measuring the angle which the sun rays hit our planet’s surface around 276 BC.
• Eudoxus proposed a system of fixed spheres around 350 BC.
• Rhia, the second largest moon of Saturn, is also the second largest moon in the solar system.
• Saturn has 82 moons.
• One year on Saturn is equal to 29.5 years on Earth.
• Titan, the largest moon of Saturn, is also the largest moon in the solar system.
• Saturn has the lowest density of all the greater than the Earth.
• Saturn is noted for its famous rings.
• Hipparchus also measured the length of the year within minutes of the modern value.
• Hipparchus observed and compared the brightness of 850 stars and arranged them into order of brightness or magnitude.
• Jupiter is a jovian planet with a volume 1,300 times that of earth, 1 revolution taking 11.78 years and 1 rotation taking 9 hours 55 mins, and it has more than 60 moons.
• The rising and setting of the sun in the east and the west is a primitive version of sundial also known as gnomon.
• Venus is the hottest planet and the twin sister of earth, with 1 venus day lasting 243 earth days and it rotates clockwise on its axis.
• Claudius Ptolemy believed that the earth was the center of the universe and his Ptolemic model claimed that the planets moved in a complicated system of circles.
• Mercury is the smallest and fastest planet, with 1 revolution taking 88 days and 1 day lasting either a very thin atmosphere or none at all.
• Aristarchus was the first Greek to profess the heliocentric view and attempted to calculate the distance of the sun and the moon by geometric principles.
• A sundial is an instrument used to measure the time that is faced to the sun.
• By looking at the shadow that the gnomon cast, Babylonia and Egyptian civilization were able to observe that the sun rises in the eastern part of the sky, reaches its highest point in the midday and sets in the western part of the sky.
• saturnian planet

  1 revolution = 29.4 years, 1 rotation = 10 hours 14 mins

  has 62 moons

  Titan - largest moon in saturn and solar system

  Uranus

  uranian planet

  1 revolution = 84.01 years, 1 rotation = 17 hours 22 mins

  has 27 moons

  Neptune

  neptunian planet

  1 revolution = 164.8 years, 1 rotation = 15 hours 34 mins

  has 14 moons
• Mars is a reddish planet and home for the largest volcano in the solar system, with two moons named phobos and deimos, half the size of earth's diameter and less density.
• Saturn is a saturnian planet with 1 revolution taking 29.4 years and 1 rotation taking 10 hours 14 mins, and it has 62 moons.
• Uranus is an uranian planet with 1 revolution taking 84.01 years and 1 rotation taking 17 hours 22 mins, and it has 27 moons.
• The point where the sun rises and sets in the horizon varies in a year and changes in the variation are related to weather and seasonal changes in the climate.
• The geocentric model of the universe posits that the sun, the moon, the five known planets and the stars are attached to spheres which carry them as they revolve around the stationary earth.
• Neptune is a neptunian planet with 1 revolution taking 164.8 years and 1 rotation taking 15 hours 34 mins, and it has 14 moons.
• Hipparchus developed a method for predicting the times of lunar eclipses to within a few hours.
• The earth's axis is not perpendicular to the planet and is tilted on its axis approximately 23.4 degrees, giving the different seasons in earth.
• Retrograde motion is a perspective effect caused when earth passes a slower moving outer planet that makes the planet appear to be moving backwards relative to the background stars.