You could have used any of the following methods to shorten the length of the method you've used. The first one is a straight forward method in which you initialize the array when you declare it.
The second method is you create a string which contains all the image names with their extension delimited by comma (,) and perform a split operation on that string. As a result of that split operation it will return an array and each element of that array will hold an image name.
image = new Array("aries_sm.jpg","taurus_sm.jpg","gemini_sm.jpg","cancer_sm.jpg","leo_sm.jpg","virgo_sm.jpg","libra_sm.jpg","scorpio_sm.jpg","sagittarius_sm.jpg","capricorn_sm.jpg","aquarius_sm.jpg","pisces_sm.jpg");
But from my point of view you can go for the first method used
var imgnames = "aries_sm.jpg,taurus_sm.jpg,gemini_sm.jpg,cancer_sm.jpg,leo_sm.jpg,virgo_sm.jpg,libra_sm.jpg,scorpio_sm.jpg,sagittarius_sm.jpg,capricorn_sm.jpg,aquarius_sm.jpg,pisces_sm.jpg";
var image = imgnames.split(",");