'Appear' would become 'appeared' in the past tense so the sentence would simply be 'some stars appeared to be brighter than others'.
The stars shone brightly in the sky.
Stare is present tense. The past tense is stared, and the future tense is will stare.
"Stare" is a present tense verb.
The past tense is blurred.
The past tense is shone.
The future tense of appear is will appear.
Appear is present tense.
future tense
The past tense of appear is appeared.
The past tense is appeared.
The past continuous tense is: was/were appearing.