Sejak tahun 2006 silam, Pluto telah kehilangan gelarnya sebagai planet di dalam Tata Surya (Solar System) kita dan dikategorikan sebagai “planet katai” atau benda langit berukuran lebih kecil dari planet.

Mengingat hingga kini tidak ada planet besar lain di Tata Surya yang lebih jauh selain planet katai Pluto, maka ilmuwan dunia memutuskan Tata Surya kita hanya mempunyai 8 planet saja. Maka planet Neptunus pun dinobatkan sebagai planet terluar.

Namun, hal itu sepertinya bakal berubah. Usut punya usut, ahli astronomi dari Universitas Cambridge dan Universitas Madrid telah menemukan tanda-tanda dari keberadaan planet lain, di luar Pluto.

Semua itu berawal saat ilmuwan mengetahui pola gerakan aneh pada planet-planet kerdil di sekitar Pluto yang biasa disebut ‘ETNO’. Lintasan planet ETNO baru-baru ini diketahui mempunyai kecenderungan untuk berubah-ubah, layaknya terkena gaya gravitasi sebuah planet besar.

“Dari perubahan orbit (lintasan) planet ETNO yang tidak diperkirakan sebelumnya itu, membuat kami yakin ada dorongan dari benda langit lain. Dorongan itu juga mengubah susunan planet ETNO,” ujar Carlos de la Fuente Marcos, ahli astronomi dari Universitas Madrid, (15/01/2015).

Dr. Marcos pun menduga sumber dorongan dahsyat itu berasal dari planet misterius. Bahkan, dia mengatakan bila setidaknya ada lebih dari satu planet misterius yang mampu menyebabkan planet-planet kerdil ETNO berubah lintasannya!

“Jumlah pastinya belum pasti mengingat data masih terbatas, namun perhitungan kami menunjukkan setidaknya ada dua planet baru bahkan lebih di Tata Surya kita,” tambah Dr. Marcos.

new solar system outer planet-X
New view of the Outer Solar System.

Sebelumnya, ilmuwan memang mempunyai teori bila tidak ada planet yang mampu mempunyai lintasan melingkar di luar planet Neptunus. Lintasan melingkar dikenal sebagai salah satu tanda bahwa planet tersebut mengelilingi matahari dan menjadi bagian Tata Surya kita.

Akan tetapi, kemudian ditemukanlah Pluto yang berhasil membantah teori itu. Meski akhirnya Pluto sendiri dinyatakan tidak lagi memenuhi ‘syarat’ sebagai sebuah planet karena ukurannya terlalu kecil.

Bila prediksi ilmuwan akan adanya dua planet lain yang berada dalam Tata Surya kita tenyata benar, sekali lagi teori tak adanya planet besar dibelakang Puto akan terbantahkan. Selain itu, penemuan itu juga akan merubah susunan planet yang ada di Tata Surya saat ini, bukan lagi 8 planet namun 10 planet.

Tapi itu pun harus dapat dilihat dulu sebesar apa ukuran planetnya. Apakah keberadaan planet misterius ini yang membuat konspirasi selama ini, mengenai sebuah planet yang tak bernama, lalu dinamakan sebagai “Planet-X”? Banyak konspirasi hingga penamaan Planet-X ini, dan menyebutkannya sebagai Planet Nibiru atau Planet Anunnaki atau Planet Harcobulus.

Entah apa planet-planet itu berbeda atau hanya satu, namun yang jelas banyak peneliti, ilmuwan, astronomis hingga saintis yang menduga bahwa tidak tertutup kemungkinan bahwa keberadaan “Planet Besar” itu bisa jadi memang ada.

Bagi ilmuwan, Planet-X memang banyak menuai kontroversi dan konspirasi selama ini. Planet misterius ini disinyalir memiliki lintasan sangat elips bagaikan lintasan komet. Oleh karenanya, maka ia butuh ribuan tahun untuk kembali lagi mendekati matahari lalu mengelilinginya dan kemudian kembali menjauh.

Planet-X inilah yang dituduh dapat menyebabkan “kiamat kecil” karena terancamnya planet-planet lain di Tata Surya akibat ukurannya yang sangat besar maka gravitasinya juga sangat besar.

Gravitasinya dapat “merusak” jalur planet lain bahkan lintasan dan atmosfir hingga gravitasi planet-planet lain termasuk Bumi jika Planet-X masuk dari luar Pluto untuk kembali lagi mendekati Matahari, setelah ribuan tahun ia menjauh. Mungkinkah dorongan-dorongan gravitasi yang mengubah susunan planet ETNO adalah akibat dari keberadaan Planet-X? Jika benar, selamat datang hari kiamat. (Daily Mail).

Could there be another Pluto-like object out in the far reaches of the Solar System? How about two or more?

Earlier this week, we discussed a recent paper from planet-hunter Mike Brown, who said that while there aren’t likely to be any bright, easy-to-find objects, there could be dark ones “lurking far away.” Now, a group of astronomers from the UK and Spain maintain at least two planets must exist beyond Neptune and Pluto in order to explain the orbital behavior of objects that are even farther out, called extreme trans-Neptunian objects (ETNO).


We do know that Pluto shares its region Solar System with more than 1500 other tiny, icy worlds along with likely countless smaller and darker ones that have not yet been detected.

In two new paper published this week, scientists at the Complutense University of Madrid and the University of Cambridge noted that the most accepted theory of trans-Neptunian objects is that they should orbit at a distance of about 150 AU, be in an orbital plane – or inclination – similar to the planets in our Solar System, and they should be randomly distributed.

But that differs from what is actually observed. What astronomers see are groupings of objects with widely disperse distances (between 150 AU and 525 AU) and orbital inclinations that vary between 0 to 20 degrees.

“This excess of objects with unexpected orbital parameters makes us believe that some invisible forces are altering the distribution of the orbital elements of the ETNO,” said Carlos de la Fuente Marcos, scientist at UCM and co-author of the study, “ and we consider that the most probable explanation is that other unknown planets exist beyond Neptune and Pluto.”

He added that the exact number is uncertain, but given the limited data that is available, their calculations suggest “there are at least two planets, and probably more, within the confines of our solar system.”

In their studies, the team analyzed the effects of what is called the ‘Kozai mechanism,’ which is related to the gravitational perturbation that a large body exerts on the orbit of another much smaller and further away object. They looked at how the highly eccentric comet 96P/Machholz1 is influenced by Jupiter (it will come near the orbit of Mercury in 2017, but it travels as much as 6 AU at aphelion) and it may “provide the key to explain the puzzling clustering of orbits around argument of perihelion close to 0° recently found for the population of ETNOs,” the team wrote in one of their papers.



They also looked at the dwarf planet discovered last year called 2012 VP113 in the Oort cloud (its closest approach to the Sun is about 80 astronomical units) and how some researchers say it appears its orbit might be influenced by the possible presence of a dark and icy super-Earth, up to ten times larger than our planet.

“This Sedna-like object has the most distant perihelion of any known minor planet and the value of its argument of perihelion is close to 0°,” the team writes in their second paper. “This property appears to be shared by almost all known asteroids with semimajor axis greater than 150 au and perihelion greater than 30 au (the extreme trans-Neptunian objects or ETNOs), and this fact has been interpreted as evidence for the existence of a super-Earth at 250 au. In this scenario, a population of stable asteroids may be shepherded by a distant, undiscovered planet larger than the Earth that keeps the value of their argument of perihelion librating around 0° as a result of the Kozai mechanism.”

Of course, the theory put forth in two papers published by the team goes against the predictions of current models on the formation of the Solar System, which state that there are no other planets moving in circular orbits beyond Neptune.

But the team pointed to the recent discovery of a planet-forming disk around the star HL Tauri that lies more than 100 astronomical units from the star. HL Tauri is more massive and younger than our Sun and the discovery suggests that planets can form several hundred astronomical units away from the center of the system.

The team based their analysis by studying 13 different objects, so what is needed is more observations of the outer regions of our Solar System to determine what might be hiding out there.

Further reading:
Carlos de la Fuente Marcos, Raúl de la Fuente Marcos, Sverre J. Aarseth. “Flipping minor bodies: what comet 96P/Machholz 1 can tell us about the orbital evolution of extreme trans-Neptunian objects and the production of near-Earth objects on retrograde orbits”. Monthly Notices of the Royal Astronomical Society 446(2):1867-1873, 2015.

C. de la Fuente Marcos, R. de la Fuente Marcos. “Extreme trans-Neptunian objects and the Kozai mechanism: signalling the presence of trans-Plutonian planets? Monthly Notices of the Royal Astronomical Society Letters 443(1): L59-L63, 2014.

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