Just days after the launch of THEMIS, NASA's mission to unravel the mysteries of the aurorae, the international scientific community is celebrating the start of the International Heliophysical Year (IHY).

According to the very po-faced announcement, this is "a year of scientific collaboration and public engagement events aimed at understanding space weather and the Sun's true effects throughout the Solar System".

All space weather in our solar system originates in the sun. Its activity - from run-of-the-mill sun spots, bog-standard solar wind through to solar flares and the even more impressive coronal mass ejections - determines it all.

Researchers have worked hard to understand the way the sun interacts with Earth, but the European Space Agency(ESA) says it is now time to think bigger.

Hermann Opgenoorth, European Space Agency head of solar system missions division, argues that we are "on the threshold of being able to investigate the interconnectivity of the whole Solar System".

The ESA has a vast fleet of craft at its disposal, from the 20-year-old Ulysses which is now on its third orbit of the sun, to the Cluster spacecraft, and the SOHO observatory.

Plasma instruments of probes ESA has sent to our sister planets Mars and Venus are also gathering data that will help researchers build a more complete picture of the sun's influence on all the planets.

But the IHY is also about raising awareness. Carine Briand, Observatoire de Paris à Meudon, and the co-chair of the European coordinating committee for IHY, says that when you say "astronomy", very few people think of our own star. This is one of the things the organisers of the IHY are hoping to change. ®

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