The process in which the nuclei of two atoms are merged together, releasing large amounts of energy
nuclear fusion
The idea that a large object roughly the sane size and mass as the planet Mars collided with the Earth, releasing rocks that were pulled together to form the Moon.
collision hypothesis
Respiration is the __________ of carbon dioxide, while photosynthesis is the sink.
source
The name of our galaxy
Milky Way galaxy
The hypothesis that explains mass extinction 65 million years ago.
Alvarez hypothesis
The moon is covered by circular dips called __________.
craters
When plants and animals decomposed, _________ is released in the air.
carbon dioxide
A dense part of a nebula in which new stars are formed
stellar nursery
The roundness of the Moon suggests the Moon has formed and been made stable mainly due to its ___________.
gravity
The idea that the moon is a large asteroid that has been pulled into orbit around the Earth.
capture hypothesis
Some asteroids can be pulled towards the Earth by the force of ________
gravity
Asteroids are objects in space which are made out of __________
rocks
a cloud of interstellar dust
nebula
The piece of rock left behind after a meteor collides with the Earth's surface.
meteorite
Name the process in D
respiration
The element that has the biggest proportion of the universe
hydrogen
The idea that the Moon and Earth formed together, close to each other, at the same time.
co-formation hypothesis
A huge, red-coloured star that is formed when a massive star expands towards the end of its life,
red supergiant
Name the process in B
combustion
An asteroid that enters the atmosphere.
meteor
Name the process in C
respiration
Any substance that has mass, which is usually made up of atoms or molecules.
matter
The explosion of a massive star at the end if its life, which produces a nebula
supernova
Name the process in A
photosynthesis
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