Astrophysics Crossword Puzzle

QUESTIONS LIST: red giant : a star that has expanded and cooled, resulting in it becoming much larger and cooler than it was before it expanded, star : a large ball of mostly hydrogen and helium that gives out light, fastest : the orbital speed of a comet is _ when it is closest to the sun, dark matter : hypothesized type of mass that cannot be observed by current methods. it is used to explain why some galaxies rotate faster than they should for their observed mass, main sequence : the life stage of a star during which it radiates energy because of fusion of hydrogen nuclei in its core, protostar : the first stage all stars go through after forming from a nebula. in this stage the star becomes hot enough for hydrogen nuclei to fuse, natural satellites : the moons that orbit planets, neutron star : the highly compressed core of a massive star that remains after a supernova, black dwarf : a star that has faded out and gone cold, red-shift : increase in the wavelength of electromagnetic waves emitted by a star or galaxy due to its motion away from us, red supergiant : a star much more massive than the sun will swell out after the main sequence stage to become this before it collapses, dark energy : a hypothesised form of energy, believed to be responsible for the universe’s ever increasing rate of expansion, supernova : the explosion of a massive star, that d, day : time for a planet to complete one whole rotation around its axis, galaxy : a large group of stars orbiting a black hole, milky way : the galaxy in which our solar system is located, centripetal force : the resultant force towards the centre of a circle acting on an object moving in a circular path, black hole : an object in space that has so much mass that nothing, not even light, can escape from its gravitational field, asteroid : small rock that orbits the sun, ice : comets are made of rock and _ , artificial satellites : man-made objects that have been sent into space and which are in orbit around the earth, elliptical : comets orbit the sun in highly _ paths, big bang : the theory that the universe was created in a massive explosion, and that the universe has been expanding ever since, nebula : a massive cloud of gas and dust