There is a finite amount of information that astronomers can gather about our universal 'neighborhood' just by looking at it, so they find ways around this by observing other stars, other solar systems, and other galaxies in order to acquire a better understanding of our own. For a long time they have searched for other stars like our sun so that they can learn more about what it might have been like in the past and what might happen to it in the future. While they have found several similar stars, only recently did they find one so incredibly close to our own star.
The star is called HIP 102152 and is located about 250 million light years away from us. It is approximately 8.2 billion years old, making it about 4 billion years older than our sun. What makes HIP 102152 so fascinating, though, is that it is an almost identical mass (0.97 whereas the sun has 1 solar mass) and chemical composition, giving astronomers an excellent source of comparison to our sun.
During the Big Bang, three elements were created: hydrogen, helium, and lithium. Scientists have observed that similar younger stars seem to have more lithium than our own, leading them to believe that stars lose lithium as they age. This is speculation, but measurements of HIP 102152 show that it has lower levels of Lithium than our star, lending credence to this idea and showing that our sun has the expected amount for its age.
Perhaps the most exciting thing about this star is that, like our sun, it is lacking the elements used to form planets and rocky bodies, meaning that something else likely 'used up' those elements when the sun was forming. This suggests that the star may have several terrestrial (rather than gas) planets orbiting it, meaning that there is a possibility that at least one could support life as we know it.