Did you know that there’s one country in the world where you would weigh less as compared to any other part of the world? For years, people were baffled by a mysterious area in Canada known as Hudson Bay.
40 years is how long it took for scientists to figure out exactly why this territory has less gravity. Ultra-precise measurements taken over four years by a pair of satellites known as GRACE (Gravity Recovery and Climate Experiment) of this territory.
GRACE, a joint mission of NASA and the German Aerospace Center, was launched into space in 2002. The two spacecraft fly 500 kilometres above the Earth, 220 kilometres apart. Using a microwave ranging system, the two spacecraft can measure distance differences between them as tiny as a micron.
That allows them to measure tiny changes in the distribution of mass – and hence gravity – on the Earth.
Reference Links
https://www.newscientist.com/article/dn11826-satellites-solve-mystery-of-low-gravity-over-canada/
https://en.wikipedia.org/wiki/GRACE_and_GRACE-FO
https://en.wikipedia.org/wiki/Hudson_Bay
https://science.howstuffworks.com/environmental/earth/geophysics/missing-gravity.htm