In a small bowl, combine unflavored gelatin in water; set aside.

Drain pears, reserving juice; set pears aside. Add enough water to the juice to measure 2 cups. Pour into a saucepan; bring to a boil. Remove from the heat; stir in gelatin mixture and lemon Jell-O until completely dissolved. Cool for about 15 minutes.

Stir in sour cream and eggnog until well blended. Chill until partially set.

Cut the oranges and pears into chunks; add to eggnog mixture.
Pour into a lightly oiled 6-cup mold. Chill until firm.