| UMBRIEL | Darkest of Uranus' largest moons (7) |
| TITANIA | Uranus' largest moon and 8th largest in the solar system, discovered by William Herschel in 1787 (7) |
| DOGSBREAKFAST | Darkest of bags (anag) (4,9) |
| JETBLACK | Darkest of colours (3,5) |
| DEADOFNIGHT | How to do the fading into the darkest of times (4,2,5) |
| GALILEO | Forename of the discoverer of the isochronism of a pendulum who improved upon the design of the refracting telescope to observe the four largest moons of Jupiter (7) |
| NEPTUNE | Planet whose largest moons are Triton and Proteus |
| FOUR | Galilean moons, the ___ largest moons of Jupiter |
| EUROPA | One of Jupiter's four largest moons |
| IAPETUS | Third-largest moon of Saturn, discovered by Giovanni Domenico Cassini in 1671 (7) |
| JUPITER | Planet whose largest moon is Ganymede (7) |
| GALILEAN | Like Jupiter's 4 largest moons |
| HIMALIA | Jupiter's fifth-largest moon, which was discovered in 1904 by Charles Dillon Perrine (7) |
| HUYGENS | Dutch polymath Christiaan ____ invented the pendulum clock and discovered Titan, Saturn's largest moon |
| RHEA | Name of a flightless ostrich-like bird; the second-largest moon of Saturn; or, the mother of Zeus (4) |
| TITAN | Any one of the gigantic offspring of Uranus (Heaven) and Gaia (Earth) after whom an element, a mighty ship, Saturn's largest moon and the body's biggest protein derive their names (5) |
| GANYMEDE | Cupbearer of Greek gods - largest moon of Jupiter (8) |
| OBERON | The second largest moon of the planet Uranus (6) |
| ARIEL | Fourth-largest moon of Uranus |
| ELARA | Eighth-largest moon of Jupiter, named after a mortal lover of Zeus (5) |
