Hallo VidyaMS und sfpugh,
Thank you very much for your explanation, sfpugh!
Just to add to what sfpugh has said, adjective endings depend on the nature of the article, the case, and the gender of the noun they are describing. Don't worry, it's not as complicated as it sounds - there are pattern and many endings repeat themselves which makes it easier to memorise.
In your example above "Siehst du die kleinen Sterne?" we have the definite article "die" and the noun "Sterne" is masculine accusative plural which makes the adjective ending "–en" in this case.
You can also have a look at lesson '5.8 Adjectives in the Nominative and Accusative' which has some good explanations and charts to look at.
There is also a lesson on this in level 2 '10.8 Adjective Endings'