The most feeble of the four fundamental forces in the universe that affect all matter. The magnitude of gravitational attraction depends directly on mass and inversely on distance squared. For instance, the gravitational attraction between you and Earth is much greater than that between you and the Sun, even though the Sun is 333,000 times more massive than Earth. The distance separating you from the Sun weakens the mutual gravitational attraction, so as you stand on Earth's surface, Earth's gravitational pull on you is 1,650 times greater than the Sun's.

Radio Programs

General Relativity V Catching ripples in the universe Friday, November 27, 2015
General Relativity IV Four views of a single quasar Thursday, November 26, 2015
General Relativity III Proof that Einstein was right Wednesday, November 25, 2015
General Relativity II Cutting the strings of gravity Tuesday, November 24, 2015
General Relativity Albert Einstein makes history Monday, November 23, 2015
On the Frontier Pushing the intergalactic frontier Monday, March 9, 2015
Neutron Stars Gravity wins the stellar battle Thursday, March 21, 2013
Wobbly Clocks Listening for cosmic “ripples” Friday, May 11, 2012
Gravity Probe B Putting a spin on space itself Thursday, May 10, 2012
General Relativity Albert Einstein “warps” the universe Monday, May 7, 2012
White Dwarfs II Stretching the light of a dead star Thursday, February 2, 2012
Gravitational Waves V The “wavy” birth of a black hole Friday, January 27, 2012
Gravitational Waves IV Silencing the rumbling Earth Thursday, January 26, 2012
Gravitational Waves III Lighting up ripples in spacetime Wednesday, January 25, 2012
Gravitational Waves II Tiny ripples from heavy objects Tuesday, January 24, 2012
Gravitational Waves Rippling across the universe Monday, January 23, 2012
Lumpy Moon Measuring the Moon’s “lumpiness” Tuesday, September 6, 2011
Apollo 15, Part II Putting Galileo to the test Sunday, July 31, 2011
Urbain Leverrier A "calculated" planetary discovery Friday, March 11, 2011

Featured Images

Hubble Space Telescope view of Abell 2744, a massive galaxy cluster
On the Frontier Monday, March 9, 2015
HST image of thousands of galaxies
Galaxies Galore Thursday, April 17, 2014
Hubble image of a galaxy cluster and the deduced location of its dark matter
Dark Universe Monday, August 5, 2013
GRAIL map of lunar surface gravity
Lunar Lumpiness Sunday, April 14, 2013
Gravitational map of the Moon compiled by the GRAIL mission
Lunar Attraction Saturday, December 15, 2012
Optical and X-ray image of the galaxy cluster Abell 383
Brilliant Darkness Friday, March 16, 2012
Map of the Moon's gravitational field
Lunar Lumpiness Tuesday, September 6, 2011


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