A coalition including the Mersey Basin Campaign, the Northwest Development Agency, Mersey Waterfront and Peel Holdings is behind the contest to design an observatory that could attract 250,000 visitors a year.
The scheme, which will replace a disused radar tower, must meet high sustainability standards and include renewable energy.
The winning design will be announced in March. It is one of three schemes aimed at generating tourism, including Sefton Water Centre.
