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Two New Dwarf Planets Discovered in Outer Solar System

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Lisa Winter

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602 Two New Dwarf Planets Discovered in Outer Solar System
Dwarf planet Eris. ESO/L. Calçada and Nick Risinger (

Astronomers have now confirmed the discovery of two new dwarf planets: 2013 FY27 and 2013 FZ27. This announcement is especially exciting considering that last week, dwarf planet 2012 VP113 (nicknamed Biden, because of Joe Biden, “VP” of the United States. Get it?! Womp womp.) was also confirmed by the same group. These three dwarf planets were all discovered using the Dark Energy Camera on the Blanco telescope in Chile.

In order to be categorized as a dwarf planet, a celestial body must orbit the sun directly (as opposed to a moon which would orbit the planet directly and the sun indirectly) and be massive enough that its own gravitational force created its round shape. Regular planets must have an orbit that doesn’t intersect with another planet’s orbit, while dwarf planets are free of that restriction. (Side note: this is where Pluto went wrong and had to be reclassified when the definitions were set in 2006).


Dwarf planet 2013 FZ27 is currently about 50 astronomical units (1 AU = 1 average Earth distance from the Sun) away from the Sun on the far end of the Kuiper Belt. The diameter is roughly 600 km (372 miles) across.

FY27 is just over 80 AU away from the sun and its 3.0 magnitude means that it is actually the ninth brightest object past Neptune. There is a little variation in the diameter, as it could be 760-1,500 km (472-932 miles) but it is most likely right around 1,000 km (620 miles). 

Scientists speculate that dwarf planets could be much more abundant in the outskirts of the solar system than is currently known. Objects in the Kuiper Belt are so distant, they reflect light fairly poorly, which makes them hard to detect. Using the Blanco’s Dark Energy Camera, more of these objects could come to light. The astounding 570 megapixel camera (as a comparison, an iPhone is 8 megapixels) was first put into use in 2012 and is able to detect faint light better than previous devices. We could very well see a surge in the number of known dwarf planets in our solar system as more of the collected data is processed.


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