A dwarf planet will become the brightest comet

The dwarf planet 2003 EL61, which is shaped like a rugby ball, will approach Neptune and be thrown into the inner solar system, but this will happen in about 2 million years

An unusual dwarf planet in the Kuiper Belt is on its way to becoming the brightest known comet. 2003 EL61 is a rapidly spinning rugby ball-shaped rock. Prof. Mike Brown from the California Institute of Technology (Caltech) calculated that the object may come very close to the planet Neptune. "If this happens, Neptune's gravity will throw the object into the inner solar system and turn it into a short cycle comet.

If you come back here in two million years, EL61 will be a comet, Prof Brown said. "When it becomes a comet it will be the brightest comet ever seen."

Strange ball

2003 EL61 is a large object that resides in the Kuiper belt and is shaped like a cigar or a rugby ball, in its long part it is equal to the diameter of Pluto but its mass is only about one third that of the ex-planet. But it is unusual - it rotates around its axis every four hours and its shape is elongated. The dwarf planet is composed of rocks and a thin layer of water ice on its surface. The other objects in the Kuiper belt contain much more water.

Computer simulations conducted by Brown showed that the object is in an unstable orbit that will eventually bring it to a close encounter with Neptune. The pull of the eight planets may, when it affects such an object, throw it into the inner solar system, throw it out into the Oort cloud, or push it out of the solar system into interstellar space. Therefore, the orbits of Kuiper belt bodies tend to be stable, but the area is considered a reservoir for short-lived comets. From time to time some of these lumps must be pushed in.

Brown and his colleagues arrived at this scenario due to the physical properties and behavior of the bone. About 4.5 billion years ago the object that became 2003 EL61 had a spherical shape that was half ice and half rock like Pluto and was also similar in size. At some point in its early history it was struck by another large object from the Kuiper Belt and the ice evaporated or broke off, leaving it with its strange shape. The ice that flew off its surface became several moons surrounding it. As expected these moons are composed of almost pure ice. Parts of this ice may have already made their way into the inner solar system as part of the cometary material. The impact caused the object to spin rapidly and as mentioned also to its elliptical shape.

A similar thing, says Brown, also happened to the planet Hema (Mercury), which only had its rocky core left. Brown presented his research at this week's meeting in Seattle of the American Astronomical Union.

The page of 2003 EL61