About: http://webisa.webdatacommons.org/69401679

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	Monitoring the Earth's mass is difficult because the gravitational effects exerted by the sun and moon and other planets are complicated.
http://www.w3.org/ns/prov#wasQuotedFrom	phys.org