The number of exoplanets with detected atmospheres is rapidly increasing. Exoplanet atmospheres present an intriguing opportunity to evaluate planetary habitability, and a critical component of that evaluation will be the unique properties of the host star. I will present recent observations of an extended exoplanet atmosphere, revealed by the first detection of H-alpha absorption in the transmission spectrum of the transiting exoplanet, HD189733b. The mechanism for causing such an extended atmosphere is almost certainly tied to the electromagnetic radiation and particle wind of the host star. While main sequence low-mass stars have relatively weak winds that are difficult to detect directly, such measurements are critical for understanding the planetary atmospheres in the system. I will review a technique to measure the mass loss rate of a solar like star by detecting its astrosphere, or the interface between the stellar wind and the surrounding interstellar medium, a stellar analog to the heliosphere which surrounds our own solar system. I will discuss a recent Hubble program to search for astrospheres in several nearby stars, including some that host their own planetary systems.