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 …
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 …
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 …
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 …
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 …
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 …
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 …
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 …
What is a light-year and how is it used?? - NASA
A light-year is a unit of distance. It is the distance that light can travel in one year. Light moves at a velocity of about 300,000 kilometers (km) each second. So in one year, it can travel about 10 …
StarChild: Comets - NASA
Scientists believe that comets are the debris left from the solar nebula which condensed to form the Sun and planets in our solar system. Most comets are thought to originate in a huge cloud …