This guide from Nasa explains what happens when the powerful magnetic fields in and around the sun reconnect, which could lead to a "solar superstorm".
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Foreign Secretary Phillip Hammond said there will have to be a "trade-off" on access to the EU single market and migration controls.
A man arrested on suspicion of murdering Melanie Hall 20 years ago has been released on police bail. She disappeared in Bath in 1996.
The stakes are high for the Labour leader, writes Chris Ship - will another general election be on the cards in the coming months?