Our Dwarf Planets Trivia Quiz

Answer: Haumea

Haumea is the third largest of the five dwarf planets in volume, although it is also the most oblong in shape of them all, with estimated dimensions of 2,100 × 1,680 × 1,074 km. It has an orbit of 283.77 years with a very fast rotational period (day) of just 3.9 hours.

In January of 2017, Haumea was discovered to have a ring in addition to its two moons. It was determined to have a radius of about 2,287 km, a width of roughly 70 km. This is the first Trans-Neptunian object (outside of Neptune's orbit) discovered to have a ring system.

Answer: Pluto

Pluto was discovered by Clyde W. Tombaugh in 1930 and was originally classified as our solar system's ninth planet. It remained so until the discoveries of more planetoids in the Kuiper Belt of similar size, which prompted the International Astronomical Union in 2006 to better define what qualified as a planet.

First, a body has to have established a stable orbit around the Sun. Second, a body has to have developed a spheroidal shape (hydrostatic equilibrium). Third, a body has to have cleared its debris field (Pluto doesn't qualify).

Answer: Ceres

Ceres was discovered by Giuseppe Piazzi in 1801 and is the only one of the five dwarf planets this side of Neptune. More specifically, it can be found within the main asteroid belt between Mars and Jupiter (slightly closer to Mars). Ceres orbits the sun every 4.6 years, and its day (rotation period) lasts 9 hours and 4 minutes.

Answer: Makemake

When it was discovered, Makemake was given the official designation '2005 FY9', but the team also called it 'Easterbunny' due to having been discovered shortly after Easter. Makemake was chosen to honour that connection as Rapa Nui is also known as Easter Island.

Makemake has an estimated diameter of 1,360 to 1,480 km, making it the second smallest of the five dwarf planets. It orbits the sun once every 306.21 years and its rotation period (day) is estimated at 22.83 hours. It has just one known satellite, discovered in 2015, that is designated S/2015 (136472) 1 and nicknamed MK2.

Answer: Ceres

While Ceres is the largest asteroid within the Main Belt, it is still the smallest of the dwarf planets in our solar system. It has a diameter of approximately 945 km (nearly the length of the UK from top to bottom).

In 2015, the NASA space probe 'Dawn' became the first mission to establish orbit around a dwarf planet.

Answer: Eris

Eris is *almost* the same size as Pluto, with a diameter of 2,326 km (about 50 km less), but its mass is approximately 0.27 times more than that of Pluto. This has been calculated from the relation to Eris' moon Dysnomia.

When Eris was first discovered (by Michael Brown, Chadwick Trujillo and David Rabinowitz) in 2005, it was estimated to be slightly larger (in volume) than Pluto, but after the New Horizons mission did its flyby of Pluto in 2015, more accurate measurements confirmed Pluto as being the larger of the two.

Answer: Haumea

Haumea was discovered by the team led by Michael Brown from observations made at the Mauna Loa Observatory in Hawaii. The name Haumea - the Hawaiian goddess of childbirth - was chosen to honour this association. And Haumea's two moons were also named after two of the goddess Haumea's daughters: Hiʻiaka and Nāmaka.

Answer: Pluto

Pluto is approximately 2,376 km in diameter and has a surface area roughly equivalent to the size of Russia. While it is the largest of the dwarf planets by volume, it is only the second on the list when considering mass.

Pluto orbits the sun once every 247.94 years, and has a day that lasts 6.387 days. There are five (known) moons orbiting this dwarf planet, named Charon, Styx, Nix, Kerberos, and Hydra.

Answer: Makemake

Ceres was discovered first (1801), then Pluto in 1930. The other three were discovered in quick succession by the same team led by Michael Brown.

Haumea was the first new dwarf planet discovered on December 28, 2004, but it did not receive a name until September of 2008.

Eris was discovered on January 5, 2005. It was officially named in September of 2006 after the Greco-Roman goddess of strife and discord.

Makemake was the last to be spotted on March 31, 2005. The name 'Makemake' was designated in July of 2008.

Answer: Eris

Eris has an eccentric orbit, on an axis about 44 degrees off from the plane of Earth's orbit (and that of most of the seven other planets). It completes an orbit of the sun every 559.07 years, reaching an estimated maximum distance from the sun (the aphelion) of 97.457 AU (1 Astronomical Unit is the distance from the Earth to the Sun), with the closest approach (the perihelion) being 38.271 AU.

To compare, Pluto's maximum distance from the sun is 49.305 AU.