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 that the force of gravity is proportional to the product of the two masses (m 1 and m 2 ), and inversely proportional to the square of the distance ...
Matter in Motion: Earth's Changing Gravity | NASA Earthdata
Dec 28, 2020 · This map, created using data from the Gravity Recovery and Climate Experiment (GRACE) mission, reveals variations in the Earth's gravity field. Dark blue areas show areas with lower than normal gravity, such as the Indian Ocean (far right of image) and the Congo river basin in Africa. Dark red areas indicate areas with higher than normal gravity.
Teachers' Center Activity: Gravity Effects on Planet Motion - NASA
Gravity and Its Effect on Planetary Orbits 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 distance between the objects
StarChild: Glossary - NASA
A cluster of stars, dust, and gas held together by gravity. GAMMA-RAYS Penetrating short wave electromagnetic radiation of very high frequency. GEOSYNCHRONOUS An orbit in which a satellite's rate of revolution matches the Earth's rate of rotation. This allows the satellite to stay over the same site on the Earth's surface at all times.
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 direct observation) matter, interacting gravitationally with the normal, visible matter in the universe, exists.
Glacier Power: How do Glaciers Move? | NASA Earthdata
Apr 17, 2025 · The ice flows like a conveyor belt driven by gravity and ever mounting snows. Ablation Zone: Where the glacier loses ice through melting, calving, and evaporation Output Zone: In this zone, the glacier loses ice. This is the lower region of the glacier. Meltwater flows out to the terminus through hidden channels and tunnels. Oldest ice is the ...
The Case of the Missing Waves | NASA Earthdata
Gravity waves are a real challenge because they are largely invisible to climate and weather models. The crux of the problem is the way satellites see them. Satellite instruments sweep the atmosphere in either a vertical or horizontal plane, so their measurements are either one- …
StarChild: Galaxies - NASA
A galaxy is a cluster of stars, dust, and gas which is held together by gravity. Galaxies are scattered throughout the universe and they vary greatly in size. A galaxy may be alone or it may be in a large group of galaxies called a "supercluster". Galaxies are classified by scientists according to their shape and appearance.
StarChild: Glossary - NASA
An invisible object in outer space formed when a massive star collapses from its own gravity. A black hole has such a strong pull of gravity that not even light can escape from it. BLUR To make less clear, to run together. BIG BANG THEORY A theory that says the universe began with a super-powerful explosion. BOLT A flash of lightning. BOULDER
What makes stars shine - NASA
It is this energy which causes the star to shine and stops it from collapsing due to the pull of gravity. Does the conversion of this tiny bit of mass into energy create enough energy to account for the Sun’s output of 390,000,000,000,000,000,000,000,000 Watts?