Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. GJ 3021, formally cataloged as Gliese 3021, is a binary star system approximately 57 light-years away in the constellation of Hydrus. The visible star in the system, A, is considered to be a Solar twin. As of 2000, it has been confirmed that an extrasolar planet orbits the star. It is of note for being a relatively Sun-like star not very far from the Sun that is home to an extrasolar planet. As a nearby Sun-like star, the last decade has seen GJ 3021A being studied carefully for the first time, especially after its substellar companion was discovered.