Chapter 27 Earth, Moon & Solar System

Age of the Earth The earth is thought to be about 4.5 billion years old. Model of Earth & Moon

The earth is about 384,400km from the moon. It would take about 3 days in a space craft to reach the moon from earth.

Each rotation of the earth takes 24 hours.

Sun Rise and Sun Set

Eratosthenes Greek mathematician who was the first to estimate the diameter of the earth.

Newgrange Built 5,000 years ago by farmers during the Stone Age. On the shortest day of the year (21st Dec.) and for a couple of days either side the sun is low enough to shine down the main passage and light the chamber inside.

Lunar Phases

Aristarchus Greek Scientist who tried to measure the angle between the moon, the earth & the sun.

Eclipses Two types: Solar eclipses & Lunar Eclipses Eclipses Two types: Solar eclipses & Lunar Eclipses. A solar eclipse (as seen from the planet Earth) is a type of eclipse that occurs when the Moon passes between the Sun and Earth, and when the Moon fully or partially blocks the Sun.

Solar Eclipse Region A: Umbra – A circular shadow between one to two hundred km wide which crosses the earth. Region B: Penumbra – Region in which you see a partial eclipse.

Lunar Eclipse The moon turns a red colour due to light Passing through The earth’s atmosphere and forming a giant circular Sunset in the moons direction.

The Moon Main features on surface of moon are craters seas Impact Craters - are the remains of asteroid strikes. As the moon has no atmosphere any marks (e.g. footprints) remain on the surface forever. Seas – are the remains of ancient lava plains. They were called seas by early astronomers who thought they were real seas. An unusual feature of the moon is that we only see one side of it.

We only see one face of the moon because the time for the moon to travel around the earth (27.3 days) is exactly the same time it takes for it to spin once on its axis.

The Planets The 8 planets can be divided Into two groups: a) The rocky inner four planets (Mercury, Venus, Earth & Mars) b) The outer four gas planets (Jupiter, Saturn, Uarnus & Neptune)

The fastest you are lightly to travel is On a transatlantic jet speed is about 900km/hr. Using a transatlantic jet it would take about two weeks to reach the moon and 19 years to reach the sun.