How astronomers work out the size of the solar system

The size of the solar system is defined by the volume of space over which the sun's influence exceeds those of other nearby stars in the Milky Way galaxy. This influence derives from two fundamental forces of nature: gravity ...

Mars likely had cold and icy past, new study finds

The question of whether Mars ever supported life has captivated the imagination of scientists and the public for decades. Central to the discovery is gaining insight into the past climate of Earth's neighbor: Was the planet ...

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