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space × 179universe × 27
telescope × 16
space-time × 15
gravity × 14
star × 12
planet × 12
expansion × 12
big-bang-theory × 10
galaxy × 9
light × 9
black-hole × 7
solar-system × 7
astrophysics × 7
general-relativity × 7
the-sun × 6
the-moon × 6
water × 6
observational-astronomy × 5
temperature × 5
speed × 5
vacuum × 5
earth × 4
cosmology × 4
time × 4