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1) This is the distance between the sun and the earth. It is the standard unit for distance within our solar system.
3) This is a group of stars near each other in space that resemble each other in certain ways that suggest a common origin.
5) This is a galaxy consisting of mostly older stars that has no dust lane and is fairly featureless. The shape can range from spherical to highly elongated.
7) This is a galaxy with a characteristic pinwheel shape with a flat disk, central bulge, and graceful arms containing regions where young stars form.
8) This is all matter and energy, including Earth, the galaxies, and the contents of intergalactic space.
9) This is a massive ball of plasma that shines because of thermonuclear fusion in its core.
10) This is the study of celestial bodies and extra-terrestrial phenomena.

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2) This is a galaxy that does not have a regular shape, like a spiral or an elliptical galaxy. The shape of one of these is uncommon and often were once spiral or elliptical galaxies and were deformed by gravitational action.
4) This is the distance that a light travels in 365.25 earth days.
6) This is a massive, gravitationally bound system consisting of stars, interstellar gas and dust, and dark matter.