There is much debate on how the solar system began, but evidence suggests it was anything but an orderly process. In a recent research paper, astronomers pointed out that a carbon-rich asteroid in the Kuiper Belt, of all places, could provide vital clues regarding the solar system’s chaotic origins.
The asteroid, titled Kuiper Belt Object 2004 EW95, caught the attention of scientists after routine observations by Wesley Fraser, an astronomer from Queen’s University Belfast and one of the persons behind the research, revealed its odd nature. For one, its reflectance spectrum – the particular set of wavelengths an object reflects – was different from that of its surroundings. The discovery was made using the NASA/ESA Hubble Space Telescope.
The Kuiper Belt is an area beyond the orbit of Neptune that is home to asteroids and dwarf planets, like the Solar System’s famous ex-member Pluto. Most of the objects in this area are floating chunks of ice made from methane and other volatile elements. Against this background, 2004 EW95 stood out like a sore thumb.
“The reflectance spectrum of 2004 EW95 was clearly distinct from the other observed outer Solar System objects,” Tom Seccull, lead author of the paper, explained. “It looked enough of a weirdo for us to take a closer look.”
Measurements performed by Secull’s team using the Very Large Telescope (VLT) at the European Organization for Astronomical Research (ESO) determined the asteroid’s composition and confirmed its nature as a carbonaceous or C-type asteroid. This type of asteroid is the most common of its kind but is very rare in the Kuiper Belt. It is mostly found in the inner areas of the Solar System, such as the asteroid belt between Mars and Jupiter.
Other clues that pointed to 2004 EW95’s peculiar nature were the ferric oxides and phyllosilicates in its composition. These features have never been observed in other objects in the Kuiper Belt. These factors suggest that the asteroid may have been a relic from the beginning of the Solar System, originally positioned close to the Sun before a massive force flung it to its current position in the distant past.
Such an event is consistent with recent theories that detail how, during the Solar System’s younger days, the movement of the gas giants – Jupiter and Saturn – set many planetary system-wide events into motion.
One of these theories is called the grand tack hypothesis, which tells of how the movement of Jupiter influenced the formation of the smaller planets closer to the Sun, including the Earth. In this model, Jupiter started moving towards the sun shortly after its formation. Its massive gravitational force absorbed much of the materials in its path, increasing its size.
The hypothesis offers that the formation of Saturn created enough gravitational pull on Jupiter that the larger planet tacked (similar to how sailboats turn back against the wind) away from the sun. Both heavenly bodies retreated to their current positions, having removed most of the materials close to the Sun, but leaving enough materials to form the smaller planets – Mercury, Venus, Earth, and Mars.
Another theory, called the Nice model, explains that the four gas giants – including Uranus and Neptune – were originally close to each other. The movement of objects in their periphery caused Uranus and Neptune to move closer to Saturn and Jupiter, whose massive gravity was enough to push the two smaller planets away. This movement caused much smaller objects – like asteroids – to move out of their place and occupy their current position. (Related: Uranus smells, says scientist, who finds that the planet’s upper atmosphere is composed of hydrogen sulfide.)
Both theories supply the factors necessary to explain how an object as large as an asteroid could be sent over massive distances. Astronomers believe that further study of 2004 EW95 could provide further insight into the origins of the Solar System.
However, there are a number of factors complicating their research. As a C-type, 2004 EW95’s carbon-rich composition makes it appear dark against outer space. In the words of one of the authors, it’s like “observing a giant mountain of coal against the pitch-black canvas of the night sky.”
Also, 2004 EW95 isn’t exactly staying out.
“Not only is 2004 EW95 moving, it’s also very faint,” said Seccull. “We had to use a pretty advanced data processing technique to get as much out of the data as possible.”
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