pollution
comet
extinct
global warming
glacier
climate
ancestor
melt
probe
primate
orbit
a general increase in world temperatures caused by increased amounts of carbon dioxide around the Earth
the process of making air, water, soil etc dangerously dirty and not suitable for people to use, or the state of being dangerously dirty
the curved path through which objects in space move around a planet or star
an object in space like a bright ball with a long tail, that moves around the Sun
the general weather conditions usually found in a particular place
a member of your family who lived a long time ago
no longer existing
to turn from something solid into something soft or liquid
a large mass of ice that moves slowly
a member of the most developed and intelligent group of mammals, including humans, monkeys, and apes
to ask questions in order to find things out