Definition of "interplanetary" []

• Existing or occurring between planets. (adjective)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The EPOXI spacecraft is indeed in interplanetary space; during the DINET test its distance from Earth varied between 81 and 49 light seconds, which is around 50 times the distance to the Moon, around 1/4 of the distance to Mars at closest approach, and around 1/20 of the maximum distance to Mars."
• "It would enable a drastic reduction in interplanetary transit times necessary to maintain functional humans."
• "He's also a proponent of manned space travel even though his background might indicate that he would be more interested in interplanetary robotic missions."