interplanetary travel

21 LETTERS · STARTS WITH I

interplanetary travel is a valid 21-letter word worth 28 points in Scrabble and 33 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS

I1N1T1E1R1P3L1A1N1E1T1A1R1Y4T1R1A1V4E1L1

1 + 1 + 1 + 1 + 1 + 3 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 4 + 0 + 1 + 1 + 1 + 4 + 1 + 1 =28 PTS

DOUBLE WORD → 56TRIPLE WORD → 84

MEANING

What does interplanetary travel mean?