Which spacecraft significantly advanced our understanding of solar physics and its impact on terrestrial weather?

The spacecraft that significantly advanced our understanding of solar physics and its impact on terrestrial weather is Skylab. Launched in 1973, Skylab was the United States' first space station and provided crucial insights through its solar observatory experiments.

One of the most important aspects of Skylab was its ability to observe solar phenomena such as solar flares and coronal mass ejections. These observations helped scientists understand how solar activity affects the Earth's atmosphere and how it can influence things like geomagnetic storms and variations in terrestrial weather patterns.

In contrast, while the Hubble Space Telescope has made significant contributions to astronomy, its primary focus is on deep-space observations rather than solar physics. Viking 1 was primarily a Mars lander and focused on planetary science, and Apollo 11 is famed for landing humans on the Moon but did not contribute to solar physics or weather studies.