What is gravity? - NASA
Newton's "law" of gravity is a mathematical description of the way bodies are observed to attract one another, based on many scientific experiments and observations. The gravitational equation says …
Teachers' Center Activity: Gravity Effects on Planet Motion - NASA
1. Introduction: Review the definition of gravity Drop a ball and explain why it falls downward Explain that the strength of a gravitational pull is determined by the masses of the objects involved and the …
StarChild: Glossary - NASA
GRAVITATIONAL FORCE See Gravity GRAVITATIONAL PULL See Gravity GRAVITY The force of attraction between two objects which is influenced by the mass of the two objects and the distance …
How do we know that dark matter exists? - NASA
The cluster does not behave as scientists would expect it to if only the visible matter is generating the gravity present in the cluster. 'Dark matter' theory suggests that a huge amount of dark (invisible to …
StarChild: Glossary - NASA
GRAVITY The invisible force between objects that makes objects attract each other. GRAVITATIONAL PULL The attraction that one object has for another object due to the invisible force of gravity. H …
StarChild: Stars - NASA
A star is a brilliantly glowing sphere of hot gas whose energy is produced by an internal nuclear fusion process. Stars are contained in galaxies. A galaxy contains not only stars, but clouds of gas and …
StarChild: The Asteroid Belt - NASA
An asteroid is a rocky body in space which may be only a few hundred feet wide or it may be several hundred miles wide. They are considered to be debris left over from the formation of the solar …
What is the shape of the universe? - NASA
The geometry of the universe is often expressed in terms of the "density parameter", which is defined as the ratio of the actual density of the universe to the critical density that would be required to cause …
StarChild: The Planets and Dwarf Planets - NASA
The Planets and Dwarf Planets A planet is a large space body which reflects the light of a star around which it . The planets in our are classified as inner planets and outer planets. The inner planets, the …
StarChild: The Asteroid Belt - NASA
An asteroid is a bit of rock. It can be thought of as what was "left over" after the Sun and all the planets were formed. Most of the asteroids in our solar system can be found orbiting the Sun between the …