Answers to Exploration Questions: Universe

Answer: We see an object when light is given off or reflected by that object. Light travels, so it takes time for light to travel from the object to our eyes. So the farther away an object is, the longer it takes to travel. We see objects in space as they appeared when the light left it. For example, it takes light from the Sun eight minutes to reach us, so we see it as it appeared eight minutes ago. Objects outside our solar system take years to reach us, so we see them as they appeared years ago.

Answer: In 1964, Penzias and Wilson discovered cosmic microwave background radiation, the remnant glow of radiation from the Big Bang. It was the first observational evidence to support the Big Bang theory, and led most astronomers to accept this theory over the “steady state” theory that all matter is created continuously.

Answer: This graph shows that the expansion of the universe is accelerating. Until scientists discovered that the expansion of the universe was accelerating, most thought the force of gravity would slow the expansion of the universe. From this discovery, scientists infer a mysterious pressure they call dark energy.