New Dwarf Planet Discovered! Now Called Eris. Quiz

Answer: Xena

Xena was a popular TV-series about a fictional ancient Greek warrior princess on air when they were looking for planets and, according to the discovering team", they always wanted to name something 'Xena'".

Hippolyta is the queen of the Amazons in Greek mythology, Barbara is Bush and "Heeeeeeeeeeeeeeeere's Johnny".

Update April 2008: Since September 13, 2006, the dwarf planet was officially named Eris.

Answer: 2003 UB313

Although the dwarf planet was officially discovered January 8th 2005, it had already been photographed in 2003 without identifying it as a new dwarf planet. Hence the "2003" in the name.

2003 VB12 is an object beyond Pluto called "Sedna", discovered only a year earlier. Level42 and UB40 are music bands.

Answer: Nobody had previously looked in its direction

The new dwarf planet is neither very dark nor very small and, with modern space technology, it is impossible for any solar system object to hide behind anything for long. However, Eris is a long way from the ecliptic plane (the plane in which the first eight planets are orbiting). Since most planets are in this plane, it was logical to look there, and almost everyone did.

Newer measurements in April 2008 indicate that it is actually the brightest object in the solar system after Enceladus.

Answer: 44 degrees

The orbital inclination is an amazing 44 degrees. Until now Pluto held the record with 17 degrees and it was considered extremely inclined. It's no wonder nobody ever looked in its direction!

There is another similarity: like Pluto, Eris has a tiny satellite. It's called Dysnomia.

Answer: about three times as far as Pluto

The distance in 2005 was about 9 billion miles or 14.5 billion kilometres or 97 times as far as Earth or three times as far as Pluto (at that time). Since its orbit is very elliptical it can come as close as 5.3 billion kilometres which is inside Pluto's orbit. It's still really, really far away.

Answer: 300 Mars years

One orbit takes about 560 Earth years, which is 298 Mars years (close enough for me), or 910 Venus years.

Pluto's orbit takes 248 Earth years so it must take longer than that. The new dwarf planet is further away so its orbit must take longer than Pluto's.

Answer: Almost certainly larger than Pluto

Determining the size of a body so far from Earth is a tricky thing and a lot of scientific effort was directed to it. Because of its brightness and distance astronomers put the size at 1 1/2 times Pluto. According to Dr. Brown, one of the discovering team, "It is definitely/guaranteed bigger than Pluto" (different sources give different quotes). This was the biggest single fact that lead to the discussion of what constitutes a planet.

Newer measurements taken in April 2008 seemed to show that it is indeed larger, but only by a few percent (0%-8% in diameter, 27% in mass). Eris's size was estimated with the assumption of it having an average brightness, but it is actually very bright. By 2015, with data from the New Horizons spacecraft, Pluto regained its status as the largest dwarf planet, although the size difference is minimal.

Answer: A large amateur astronomer's telescope in your backyard will do

Unlike the planets in other solar systems, if you are an amateur astronomer with a large size telescope (I couldn't find the information about the minimum diameter needed) you can help the professionals with the study of this exciting new object. You can't see Pluto with the naked eye and also simple binoculars won't be enough.

Answer: 1846, Neptune

Neptune is larger than Rhea or Titania (their discovery dates are correct). Amazingly, Triton was discovered in 1846, only weeks after its parent planet. At the time of its discover, the diameter of Eris was estimated at 3300 km. It is certain that this is the biggest thing since 1846.

Answer: True

With this discovery of Eris the debate about how to define a planet heated up again, with NASA originally calling the new discovery a planet, which, at the time, made it the tenth.

Update April 2008: Because of the controversy the discovery of Eris generated, the IAU decided to give a definition of planet. As a result, objects are now classified as planets, dwarf planets, and small solar system body (SSSB). According to this definition, only the first 8 planets are now called planets. Pluto was demoted, Eris was assigned, and most interestingly, the asteroid Ceres was promoted to the status of dwarf planet.

The rest were classified as SSSB but many among them might be promoted to dwarf planet in the future. There are still many astronomers who have a different definition of planet.