The outer solar system: Something new under the sun; A miniature planet sheds light on the extremities of the solar system

The outer solar system: Something new under the sun; A miniature planet sheds light on the extremities of the solar system

Mar 29th 2014 | From the print edition

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MODERN telescopes can see things billions of light-years away, so it may seem surprising that there remains anything to be discovered in the Earth’s backyard. But there is. On March 27th, for example, in a paper published in Nature, Chadwick Trujillo of the Gemini Observatory, in Hawaii, and Scott Sheppard of the Carnegie Institution for Science, in Washington, DC, announced that they have found a new member of the sun’s retinue, in a part of the solar system of which astronomers know little.

The object in question, thought to be 450km across and provisionally dubbed 2012VP113, is much farther away than Neptune, the icy world that is the most distant of the sun’s proper planets. Neptune is about 30 astronomical units from the sun (an astronomical unit, or AU, is the average radius of Earth’s orbit, about 150m kilometres). The highly elliptical orbit followed by 2012VP113 brings it no closer to the sun than 80 AU. At its most distant, though this is hard to estimate until more data are available, it may be as much as 500 AU away.

This orbit puts 2012VP113 much farther out even than the Kuiper belt, a collection of icy asteroids beyond the orbit of Neptune in which Pluto (which was booted out of the planetary club in 2006) makes its home. Instead, the two researchers suggest their find is a member of the inner part of the Oort cloud, a collection of dwarf planets, asteroids and comets thought—but not yet proved—to surround the sun, and which may extend as much as half of the four light-year distance to Alpha Centauri. The Oort cloud is believed to be the source of many comets. But some models of how the solar system works suggest there ought to be a gulf of empty space between the Kuiper belt’s edge and the Oort cloud’s beginning, somewhere around 10,000 AU from the sun. Uncomfortably for those models, 2012VP113 sits in that gap.

The Oort-cloud-gap theory has already taken one hit. In 2003 Mike Brown, of the California Institute of Technology, discovered a dwarf planet called Sedna, 1,000km across, travelling in an orbit (see diagram) similar to that of 2012VP113—exactly where it should not have been, in other words. Finding one such body could have been a fluke. A second, though, “strongly suggests that the inner Oort Cloud is real”, according to Megan Schwamb, of the Institute for Astronomy and Astrophysics, in Taiwan, who worked with Dr Brown.

Regardless of whether Sedna and 2012VP113 are part of an inner Oort cloud, their weird orbits need explaining. They have probably not been like that from the start. The sun and its retinue condensed from a rotating disc of gas and dust, and anything produced this way should have ended up in a more-or-less circular orbit, such as those the modern planets follow.

One idea is that the two eccentrics were kicked into their orbits by a close encounter with Neptune (which is how the Kuiper belt is thought to have been created). That seems unlikely, though, for both are too far from Neptune for its gravity to have had much influence on them.

Another theory is that they were forced into their current orbits during the solar system’s youth, perhaps by a close encounter with another star that formed in the same nebula as the sun. If so, then they have probably orbited undisturbed ever since, and may thus provide a window onto the earliest years of the solar system.

Elliptical thinking

There is, however, a more intriguing possibility. Sedna, 2012VP113 and a handful of smaller objects share similar values of a particular orbital characteristic called the “argument of perihelion”, which describes the angle that their orbits form with the plane of the solar system. Computer models suggest these angles should be randomly distributed. So far, they do not seem to be. And that is a puzzle. According to Drs Trujillo and Sheppard, one possible explanation is that the gravity of something big, distant and unseen is marshalling the orbits of these smaller hunks of rock. The two researchers say their data are compatible with the idea of a giant planet lurking in the far reaches of the solar system.

“Compatible with” is not the same as “proof of”, of course. Unlike the makers of science-fiction films, most astronomers are sceptical of “Planet X” hypotheses, of which there have been plenty over the years. So far only one has proved correct—Neptune itself, whose existence was inferred in the 19th century from irregularities in the orbit of Uranus. But things should become clearer in the not-too-distant future, when new telescopes more capable of spotting dim, distant objects come into operation. When these get going, they will probably find that Earth’s backyard holds plenty more surprises.

 

About bambooinnovator
Kee Koon Boon (“KB”) is the co-founder and director of HERO Investment Management which provides specialized fund management and investment advisory services to the ARCHEA Asia HERO Innovators Fund (www.heroinnovator.com), the only Asian SMID-cap tech-focused fund in the industry. KB is an internationally featured investor rooted in the principles of value investing for over a decade as a fund manager and analyst in the Asian capital markets who started his career at a boutique hedge fund in Singapore where he was with the firm since 2002 and was also part of the core investment committee in significantly outperforming the index in the 10-year-plus-old flagship Asian fund. He was also the portfolio manager for Asia-Pacific equities at Korea’s largest mutual fund company. Prior to setting up the H.E.R.O. Innovators Fund, KB was the Chief Investment Officer & CEO of a Singapore Registered Fund Management Company (RFMC) where he is responsible for listed Asian equity investments. KB had taught accounting at the Singapore Management University (SMU) as a faculty member and also pioneered the 15-week course on Accounting Fraud in Asia as an official module at SMU. KB remains grateful and honored to be invited by Singapore’s financial regulator Monetary Authority of Singapore (MAS) to present to their top management team about implementing a world’s first fact-based forward-looking fraud detection framework to bring about benefits for the capital markets in Singapore and for the public and investment community. KB also served the community in sharing his insights in writing articles about value investing and corporate governance in the media that include Business Times, Straits Times, Jakarta Post, Manual of Ideas, Investopedia, TedXWallStreet. He had also presented in top investment, banking and finance conferences in America, Italy, Sydney, Cape Town, HK, China. He has trained CEOs, entrepreneurs, CFOs, management executives in business strategy & business model innovation in Singapore, HK and China.

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