Maybe we're considering Pluto wrong. Planet, dwarf planet – this semantic debate could be irrelevant, because in reality. , , Maybe Pluto is actually a huge comet? In an article published this week in the journal Icarus scientists from the Southwest Research Institute are putting forward a new theory that Pluto could actually be just the collection of comets. Billions of them.
Scientists usually thought that Pluto was born in the usual way for a planet: in the early days of the solar system, a stony nucleus formed amidst a mass of gas and dust, and gravity slowly accumulated more and more material leads to a small spherical ball, which we now call Pluto. But recent findings in the 1
"The current paradigm is that bodies in the outer solar system are affected by the accretion of rock and ice," says Christopher Glein, a scientist from the Southwest Research Institute and lead author of the new work. "We think that comets are leftover building blocks of larger bodies, and previously it was thought that Pluto could have been made from cometary building blocks, but we did not have the data to actually test it Step in this process. "
The data for this paper comes from two sources: the New Horizons mission, in which scientists were able to observe a nitrogen-rich glacier on Pluto called Sputnik Planitia; and the chemical composition of comet 67P / Churyumov-Gerasimenko, studied by the Rosetta probe (RIP) of the European Space Agency. The authors of the article found that the nitrogen content of the glacier was similar to what other models would predict if Pluto had been formed by the mashup of billions of comets such as 67P
"We first used information from New Horizons," says Glein Estimate how much nitrogen is on Pluto and have escaped from Pluto's atmosphere, "which is a limitation that is a target for theoretical models." Then we used Rosetta's nitrogen abundance and reduced it to the mass of Pluto scales. What was really interesting is that the two approaches give values that agree well. "
This new" giant comet "model is shocking, but also the discovery of an atmosphere on Pluto, suggesting that it might have an underground ocean, but for safe measurement researchers have also developed a so-called" solar model ", suggesting that Pluto is made of cold ice that contains a lot of nitrogen, similar to the Sun. "The solar model provides much more nitrogen than we see in Pluto," says Glein, "but we can not rule this out because we do not knowing exactly how much nitrogen has escaped from the Pluto atmosphere throughout its history. "New Horizons is" just a snapshot, "and it's unclear how nitrogen levels have changed over billions of years.
Like all strange new ideas, it is far from bulletproof, according to Glein, the biggest limitation of the model is that New Horizons ei a fairly low level of carbon monoxide on Pluto, although comets tend to carry high levels of carbon monoxide. Much of this could have been buried deep under Sputnik Planitia, so New Horizons would obviously miss discovering it on the surface, and an ocean below the surface could also have led to the destruction of carbon monoxide. "I find the latter hypothesis particularly intriguing because there are other New Horizons evidences that suggest the existence of such an ocean," he says.
While Glein thinks most scientists have kept the study warm, he does admit this, some people have raised issues with the "giant comet" connotation. "I'm not saying that Pluto is a comet," he says, "but instead its composition could be related to a model of an oversized comet." There are a lot of nuances that could easily be lost when making that distinction (19659002) Ultimately, the only way to confirm or disprove this new theory is to study Pluto directly. This means going beyond a flyby mission like New Horizons and sending an orbiter – and maybe even a lander – to Pluto. Glein chooses, for obvious reasons, to land on Sputnik Planitia, where we could try out some of these cool glaciers and analyze them with a mass spectrometer. It's hard to see such a mission getting the green light soon, but the success of New Horizons means the call to Pluto is getting louder and louder.