1. Space And Gravity
Ben Kendall 9B

2. What Is Gravity?
the force that attracts a body towards the centre of the earth, or towards any other physical body having mass.

3. What Is Mass?
a large body of matter with no definite shape.

4. What Is Weight?
a body's relative mass or the quantity of matter contained by it, giving rise to a downward force; the heaviness of a person or thing.

5. What Are The Differences Between Mass And Weight?
In the physical sciences, mass and weight are different. The mass of an object is a measure of the amount of matter in the object. Weight is a measure of the force on the object caused by a gravitational field. In other words, weight is how hard gravity pulls on an object.

6. Elliptical Orbit
In astrodynamics or celestial mechanics an elliptic orbit is a Kepler orbit with the eccentricity less than 1; this includes the special case of a circular orbit, with eccentricity equal to zero.

7. Identifying Our Planets In Our Solar System
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto

8. Planet, Natural Satellite, Artificial Satellites

9. Stars, Galaxy And Universe