If you get any of these answers wrong, the app will simply say ‘incorrect’, the game will continue. You can then make another guess on a future turn. If you’re right, finish your turn and move to the ‘End Of The Game’. Game Theory Asteroids (4) – These will always appear in pairs, which means they can be in two groups of 2 or one group of 4. Osbourne, Hannah (23 June 2017). "Forget Planet9 - there's evidence of a tenth planet lurking at the edge of the solar system". Newsweek . Retrieved 23 June 2017.

Renu Malhotra (1998). "Orbital Resonances and Chaos in the Solar System" (PDF). Solar System Formation and Evolution ASP Conference Series. 149: 37. Bibcode: 1998ASPC..149...37M. Give each player all the pieces in one colour (1 player screen, 1 telescope miniature, 12 Theory Tokens) and 2 Target Tokens. If playing in Expert Mode, each player should also attach the ‘expert panel’ to the indicated slot in their player screen. There are a couple of other game points, which keep things interesting. Every few moves you get to submit theories based on what you know, and there are conferences where the app gives all players more information about the location of Planet X – this can be a real leveller! Lowell's sudden death in 1916 temporarily halted the search for PlanetX. Failing to find the planet, according to one friend, "virtually killed him". [25] Lowell's widow, Constance, engaged in a legal battle with the observatory over Lowell's legacy which halted the search for PlanetX for several years. [26] In 1925, the observatory obtained glass discs for a new 13in (33cm) wide-field telescope to continue the search, constructed with funds from Abbott Lawrence Lowell, [27] Percival's brother. [18] In 1929 the observatory's director, Vesto Melvin Slipher, summarily handed the job of locating the planet to Clyde Tombaugh, a 22-year-old Kansas farm boy who had only just arrived at the Lowell Observatory after Slipher had been impressed by a sample of his astronomical drawings. [26]

Starting in 2018, several surveys have discovered multiple objects located beyond the Kuiper Cliff. Some of these new discoveries are close to the heliopause (120 AU) or well beyond it ( 2018 VG 18, 2018 AG 37, 2020 BE 102, 2020 MK 53). An analysis of the TNO data available prior to September 2023 shows that there is a gap at about 72 AU, far from any mean-motion resonances with Neptune. [88] Such a gap may have been induced by a massive perturber located further away.

C. de la Fuente Marcos & R. de la Fuente Marcos (1 January 2024). "Past the outer rim, into the unknown: structures beyond the Kuiper Cliff". Monthly Notices of the Royal Astronomical Society Letters. 527 (1): L110–L114. arXiv: 2309.03885. Bibcode: 2024MNRAS.527L.110D. doi: 10.1093/mnrasl/slad132 . Retrieved 28 September 2023. Chang, Kenneth (20 January 2016). "Ninth Planet May Exist Beyond Pluto, Scientists Report". The New York Times . Retrieved 22 January 2016.In essence, the game is an extended Logic Problem puzzle wrapped up into a board game. So, if logic is your thing, then you’re likely to get a lot out of Planet X. If not, it might leave you a little cold.

The player with the most points is the winner, ties broken in favor of most points scored by finding Planet X. a b c d e f g h i j k Morton Grosser (1964). "The Search For A Planet Beyond Neptune". Isis. 55 (2): 163–183. doi: 10.1086/349825. JSTOR 228182. S2CID 144255699. In certain sectors of the board, you will find a ‘Theory’ symbol. Whenever the yellow arrow on the Earth board points to or passes over, one of these, pause the game and carry out a ‘Theory Phase’.There's also the issue of size. Brown says even at 100 miles across, Gna would be one of the biggest objects seen in that part of the outer solar system. Almost all of the Kuiper belt and trans-Neptunian objects found so far are smaller than that. The Search for Planet X was touted as the next great logic/deduction game. As the story goes: “At the edge of our solar system, a dark planet may lurk. In 2015, astronomers estimated a large distant planet could explain the unique orbits of dwarf planets and other objects. Since then, astronomers have been scanning the sky, hoping to find this planet. In The Search for Planet X, players take on the role of astronomers who use observations and logical deductions to search for this hypothetical planet. Each game, the companion app randomly selects an arrangement of objects and a location for Planet X following predefined logic rules.”

After 1978, a number of astronomers kept up the search for Lowell's PlanetX, convinced that, because Pluto was no longer a viable candidate, an unseen tenth planet must have been perturbing the outer planets. [44] Than, Ker (18 June 2008). "Large 'Planet X' May Lurk Beyond Pluto". Space.com . Retrieved 18 July 2016. a b c Trujillo, C. A.; Sheppard, S. S. (2014). "A Sedna-like body with a perihelion of 80 astronomical units" (PDF). Nature. 507 (7493): 471–474. Bibcode: 2014Natur.507..471T. doi: 10.1038/nature13156. PMID 24670765. S2CID 4393431. Archived from the original (PDF) on 2014-12-16 . Retrieved 2016-01-25. a b David A. Weintraub (2014). Is Pluto a Planet?: A Historical Journey through the Solar System. Princeton University Press. p.141. ISBN 978-1400852970. However, Brown notes that even though it might approach or exceed Earth in size, should such an object be found it would still be a "dwarf planet" by the current definition, because it would not have cleared its neighbourhood sufficiently. [78] Kuiper cliff and "Planet Ten" [ edit ]a b Batygin, Konstantin; Brown, Michael E. (20 January 2016). "Evidence for a distant giant planet in the Solar system". The Astronomical Journal. 151 (2): 22. arXiv: 1601.05438. Bibcode: 2016AJ....151...22B. doi: 10.3847/0004-6256/151/2/22. S2CID 2701020. It’s also worth understanding the concept of the ‘visible sky’– at all times, the Earth board will be covering up half of the sectors in the game. Whenever you Survey/Target, you can only ask for information in the half that is currently uncovered. Marc W. Buie; William M. Grundy & Eliot F. Young (July 2006). "Orbits and photometry of Pluto's satellites: Charon, S/2005 P1, and S/2005 P2". Astronomical Journal. 132 (1): 290–298. arXiv: astro-ph/0512491. Bibcode: 2006AJ....132..290B. doi: 10.1086/504422. S2CID 119386667.