Colon: Space after not before

Do this

Outer space: The new frontier

Not

Outer space : The new frontier

Don't put a space before a colon in titles or in sentences; it is bad grammar. It is fine if you are using the colon like a pipe or other divider between separate items such as in a horizontal list of links to separate pages. That is using the colon as a typographical element or decoration other than a colon and quite all right. In a title however, such as the title of a presentation, book or paper, there must be no space before the colon. Otherwise it breaks the title into two separate things which is wrong or simply bad grammar.

I hope this helps,

Thank you :-)