Sources: (In Order)
By The International Astronomical Union/Martin Kornmesser [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
CC0 Public domain https://pixabay.com/en/mercury-planet-surface-solar-system-11591/
By NASA/JPL (from Planetary Photojournal) [Public domain], via Wikimedia Commons
CC0 Public domain http://maxpixel.freegreatpicture.com/Starry-Sky-Red-Planet-Planet-Universe-Space-Mars-11012
CC0 Public domain https://www.goodfreephotos.com/astrophotography/full-view-of-jupiter.jpg.php
By NASA / JPL / Space Science Institute [Public domain], via Wikimedia Commons
CC0 Public domain https://en.wikipedia.org/wiki/Uranus
By NASA (composite image by Jcpag2012) [Public domain or Public domain], via Wikimedia Commons