Intro To Astronomy

Words you should know: Rotation: Earth spinning like a top Axis: invisible line that passes through the Earth and the North and South Poles

Words You Should Know: Revolution: Movement of one object around another… The Earth revolves around the sun Orbit: the path of the object as it revolves

Words You Should Know Longitude: Tells how many degrees East or West you are from the Prime Meridian (Greenwich, England) (vertical lines on globe) Latitude: Tells how many degrees North or South you are from the Equator (horizontal lines on globe)

Day and Night Day and night is caused by Earth’s rotation. The side of the Earth that faces the sun has day and the side that is facing away from the sun is night The amount of day and night depends on the season and your latitude

Why does the sun rise in the East and Set in the West? The Earth rotates west to east, so the sun appears to rise in the East and set in the West The exact location of the rise/set depends on the time of the year

Does the moon rise and set? Yes the moon rises and sets As the Earth rotates part of the Earth is facing the moon and part is not Due to the Moons revolution around the Earth and the shape of its orbit, the moon rises about 50 minutes later each day

Keeping Time Throughout Time Believed that Chinese had first calendar Egyptians created a calendar 6000 years ago – they knew a year was 365 days based on observations of a star (Sirius) They had 12 months of 30 days and an extra 5 days not in a month

More Calendar History Many civilizations had lunar calendars (Chinese, Babylonians, Greeks, Jews and Arabs) Julius Caesar and the Romans created a calendar very similar to our current calendar – called the Julian Calendar Current Calendar (the Gregorian calendar) was created in the 15th century

Leap Years A solar year is actually 365 days 5 hours 48 minutes and 46 seconds… So we have an extra day every 4 years Century years have a leap year only if they can be divisible by 400.