The word heliospheres is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 20
Highest Scoring Words With Friends™ Plays In The Letters heliospheres
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Seven Letter Word Alert: (29 words)
elopers, heiress, helpers, heroise, hosiers, isohels, lispers, lossier, peelers, pheeses, phisher, pieless, poesies, reheels, repeels, repiles, replies, reposes, reships, reshoes, resoils, resoles, rosehip, seepier, sleeper, slopers, soirees, spheres, spoiler