**Astronomers were astounded to find that, rather than being a featureless crater-ball as expected, the dwarf planet 2032XD420 was a world full of complex and interesting geological features, such as**

 lakes and cracks. The details revealed by Hubble allowed astronomers to make a number of detailed measurements of the surface and interior of the dwarf planet, which were then used to measure its gravity. The data revealed that 203XD420 has a density similar to Earth's - and, thus, is a possible candidate to host extraterrestrial life.

At the heart of 203XD420 lies a dwarf planet roughly twice the size of Jupiter orbiting the Sun every 2.2 Earth years.

A ring of ice covered by a dense haze is observed at 203XD420's core. At a temperature of 1,200 degrees Fahrenheit, the ice is roughly 50 percent denser than the atmosphere around it, suggesting that the core could contain a core liquid pool.

The surface of 203XD420 is dominated by water ice. The dwarf planet's surface is also covered with volcanic rings, which suggest that it is composed of a similar mix of water and rock as our own planet.

The Hubble observations show that the surface temperature varies between -200 degrees Fahrenheit to 300 degrees Fahrenheit. The planet's surface pressure, measured at 3.3 pounds per square inch, is similarly varied, ranging from 0.04 inches to 8.8 inches.

The Hubble data also revealed that 203XD420 has a rocky core. The core is estimated to be 1.7 times as large as the rocky planet's rocky mantle.

There are two possible structures that could be at 203XD420's core, both of which are consistent with observations from NASA's Spitzer Space Telescope, the European Space Agency's Herschel Space Telescope and ground-based telescopes.
The two structures have similar shapes and thicknesses, a finding that is consistent with theories that the planet is composed of large, rocky objects with an outer crust.

The first possible structure is called a "dwarf star." Such a structure is thought to consist of a rocky core surrounded by an outer layer of water ice.
This structure can be seen in the images of the planet taken by the Hubble Space Telescope, which show that 203XD420 has a distinct dwarf star-like ring. The dwarf star-like ring is about 30 times larger than our own sun's sunlit disc.

The second structure is a "plutoid." A plutoid is a planet with an inner "water ice" layer, a thickening layer on the planet's surface and an outer "rocky" layer. Pluto is a dwarf planet, while its rocky core is too hot to sustain liquid water.

The Hubble data also reveals that 203XD420 has a small moon, named J2000.combo, which orbits the planet at an estimated distance of 0.5 to 2.5 AU. This makes J2000.combo the closest moon-like object to 203XD420.
"J2000.combo is probably the smallest object that orbits a planet of this size, making it the most compact example of a planetary system," concludes the paper.
If this is the only planet orbiting a planet with two moons, the planets might only be made of rock, not ice.
The paper does not suggest any theories to explain these observations, but that could be another story.
The paper is titled: "Three-body system orbiting a trans-Neptunian object .
http://arxiv.org/abs/1311.4840 "J2000.combo is probably the smallest object that orbits a planet of this size, making it the most compact example of a planetary system."
There have been two papers that suggest the planet could be a rocky, frozen object, not a planet. The first paper , published in 2001, describes an object that orbits a planet at an estimated distance of 1 AU. The object is believed to be a small asteroid, but that study did not find any evidence of a large moon orbiting the asteroid.