Theia
Theia est planeta qui abhinc circiter 4 500 000 000 annorum cum Tellure colliserit. Ex hac collisione creata sit Luna. Quo planeta non supervivente, nomen "Theia" ab Unione Astronomica Internationali haud recognosci potest sed ab eruditis saepe adhibetur.

Bibliographia 
 Daniel Herwartz, Andreas Pack, Bjarne Friedrichs, Addi Bischoff, "Identification of the giant impactor Theia in lunar rocks" in Science vol. 344 no. 6188 (6 Iunii 2014) pp. 1146-1150
 Ian Sample, "Moon created in violent collision with Earth, clues in Apollo rocks suggest" in The Guardian (5 Iunii 2014)
 Ulrich Wiechert, A. N. Halliday, D.-C. Lee, G. A. Snyder, L. A. Taylor, D. Rumble, "Oxygen Isotopes and the Moon-Forming Giant Impact" in Science vol. 294 no. 5541 (2001) pp. 345–348

Systema Solare
Luna
Res astronomicae opinabiles
Mechanica caelestis