ConceptChecks
ConceptCheck 1-1: While a hypothesis is a testable idea that seems to explain an observation about nature, a scientific theory represents a set of well-tested and internally consistent hypotheses that are able to successfully and repeatedly predict the outcome of experiments and observations.
ConceptCheck 1-2: Shorter lifetime. The larger star has twice as much mass as the Sun. However, it consumes its nuclear fuel much more than twice as fast, so that its lifetime is shorter than the Sun.
ConceptCheck 1-3: Yes. The apparent size of an object is given by how wide it appears (in other words, the angle that it subtends). By moving a basketball near and far, it can appear very large or very small.
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