During the last decades, the heliospheric studies significantly contributed to our understanding of how the Sun’s magnetic acitivity affects the space weather of Earth in the short term and its climate change in the intermediate term. It now seems quite timely or urgent to extend this expersise to resolve two outstanding problems: 1) how the solar magnetic activity have affected the habitability of Earth and other planets in the long term, and 2) how the magnetic acivity of a star affects the habitability of an exoplanet orbiting around the star. Resolving these two problems are intimately related to revealing of the fundamental principle and diversity of dynamo process in a variety of stars, planets and satellites. A useful tool for these scientific goals is comparative heliospheric studies: comparing Earth and Mars, comparing the present Sun-Earth system and the past system, comparing solar magnetic activity and stellar magnetic activity. Comparing flares between the Sun and other stars has become very active in the last decade, and comparing prominence eruptions between the Sun and stars is becoming popular, as prominnece eruptions are regarded as a signature of coronal mass jections that can be observed from the ground. In this talk, I will review the recent observations of flares and prominence eruptions on EK Dra that is regarded as a “young Sun”, in comparison with those on the Sun. We conclude that detecting prominence eruptions on a magnetically active star is much more difficult to detect flares, and would require high S/N spectroscopy as well as a reasonable model of radiation on the star during the eruptions.