Remember how Australian scientists have been recruiting amateur astronomers in the search for the elusive ninth planet thought to orbit the solar system?

Thanks to this campaign, the team is now eyeing four unknown objects that could be Planet Nine candidates.

Citizen Search In Action

The planetary search, launched on BBC’s Stargazing Live broadcast, harnessed thousands of images captured by the Australian National University’s SkyMapper telescope in New South Wales. From there, around 60,000 eager stargazers worldwide had classified more than 4 million space objects as part of the search.

Lead researcher Brad Tucker reported that the probe is now taking a specific direction.

"We've detected minor planets Chiron and Comacina, which demonstrates the approach we're taking could find Planet Nine if it's there," Tucker said in a statement. "We've managed to rule out a planet about the size of Neptune being in about 90 percent of the southern sky out to a depth of about 350 times the distance the Earth is from the sun.”

The citizen scientists have flagged four specific objects for follow-up in the search for Planet Nine, which calculations from January 2016 suggest may be orbiting the sun. The hypothesized planet is believed to be around 10 times Earth’s size and 800 times its distance from the sun.

Astronomers will now use the telescope at Siding Spring as well as others around the world to investigate the four objects and see if they’re viable planetary candidates. Even if they don’t turn out to be likely prospects, the team celebrated achieving four years’ worth of scientific analysis in under three days.

In fact, Tucker shared, a volunteer by the name of Toby Roberts made an impressive 12,000 classifications under this citizen-search program.

The search for Planet Nine, which involved the citizen-science website Zooniverse.org, is now officially on. Take note, though, that the publicly open aspect of it has ended. ANU’s citizen search however continues via www.planet9search.org.

The Fuss Over Planet Nine

In 2014, astronomers Scott Sheppard and Chadwick Trujillo first proposed Planet Nine’s existence, broaching the discovery of space body 2012 VP113 and its shared orbital traits with the dwarf planet Sedna and other objects.

According to the two, the similarities could be answered for by a massive, unseen “perturber” that lurks in the outer spans of the solar system and tugs on the said objects.

This was bolstered by astronomers Konstantin Batygin and Mike Brown in 2016, dubbing the perturber “Planet Nine” and thinking it could be sculpting more distant objects’ orbits.

Scientists, according to Tucker, concluded from here that Planet Nine existed after they studied Pluto’s orbit. This orbit could have been affected by another planet’s gravity, the same way Neptune was actually predicted.

At present, the solar system currently has eight recognized planets, after Pluto’s planetary status was stripped in 2006. Science, however, can be expected to keep looking – a group, for instance, put forward a new way to classify planets that could likely bring the planet count to more than 100.