Scottish Secretary Michael Moore said that in 12 months people will make a choice that "will affect our nation's future forever".
"This is an absolutely defining moment and a once-in-a-lifetime choice. That's why I hope people will think carefully as they prepare for the vote.
"I firmly believe that Scotland will be stronger, more secure and more prosperous if we remain as part of the UK.
"Between now and next September I will continue to argue this case as well as providing what I believe will be robust and persuasive evidence.
"I'm sure the year ahead will be both challenging and exciting as the arguments crystallise and people prepare to cast their vote. It will also be memorable and, above all, historic.
"We are all privileged to be able to play a part in it."
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Kerrie brings you Sunday night's forecast
The highest risk of snow is from the NW later on Monday into Tuesday. For all it will remain cold with raw days and frosty, icy nights
Wintry start for some and windy. Brightening later