Is it possible to write * instead of all column names?

I have three table A,B,C. Every table has 9, 10 columns.

My current query is very long and complicated because of column names.

I just want to replace column name with *(select all)

'Select col1, col2,.....col10 from table1 
union all
select col1, col2,......,null as col10 from table2
union all
.......
'

How can i write simple query or with *;