... Tonight's Sky . ... solar system . ... Observe the Solar System . ... Spacecraft discovers solar winds weakening . ... Data from the Ulysses spacecraft, a joint NASA-European Space Agency mission, show the Sun has reduced its output of solar wind to the lowest levels since accurate readings became available. ... This border, called the heliopause, is a bubble-shaped boundary surrounding our solar system where the solar wind's strength is no longer great enough to push back the wind of other stars. ...