A Look Back at 2015: The Year in Science and Technology

greenhouse gas emissions –n. harmful gases, like carbon dioxide that scientists say cause global warming

mainstream – n. the ideas, beliefs or activities regarded as normal

recruiting –v. finding the right people to join an organization

solar system –n. our sun and the planets that move around it

patent –n. official document that gives a person or company the right be the only one to make or sell a product for a certain amount of time

organism –n. an individual living thing

human ancestor –n. a person who came before modern humans, one of the people from whom humans descended