Our Sun is about 4.6 billion years old. We know that from models of Sun-like stars, as well as through our observations of other stars of similar mass. We know that the Sun has grown hotter over time, and we know that in about 5 billion years it will become a red giant star before ending its life as a white dwarf. But there are many things about the Sun’s history that we don’t understand. How active was it in its youth? What properties of the young Sun allowed life to form on Earth billions of years ago?
If we had a time machine, we could travel to the distant past and observe the Sun’s youth directly. But since that’s not possible, we can do the next best thing. Look for young stars that are very similar in size and composition to our Sun. The spitting image of the Sun, if you will. This
has been done before with older stars. HIP 102152, for example, is a solar doppelganger that’s about 4 billion years older than our Sun. Now a team has studied a young solar doppelganger known as kappa-1 Ceti.
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