The scale of the universe can be difficult to comprehend. Pretend you are going to make a scale model with a basketball representing the Earth and a tennis ball as the Moon.
When a star explodes as a supernova, it shines brightly for a few weeks or months before fading away.
How many Earth-like planets are in our galaxy? Scientists have asked that question for hundreds of years.
(617) 495-7462Christine Pulliam
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