Goldilocks, meet Godzilla

Scientists have a good idea of where to find habitable planets. A certain number of provisos have to be met: it must have an atmosphere and be in the “Goldilocks zone”, the right distance from its parent star to have water in liquid form.

Whether this is possible depends, to a large degree, on the star and its age, and the size of the planet itself.

This is why the discovery of a “Godzilla” Earth has come as a surprise for planet hunters. Enter Kepler-10c, a planet about 560 light years from Earth in the constellation Draco, where it circles its sun-like star every 45 days.

It’s about 2.3 times larger than Earth, and was one of hundreds of planets discovered by Nasa’s spacecraft Kepler.

Using data from Kepler, scientists can tell how large a planet is – in this case about 29 000km across – but not whether it is rocky or has a firm surface. However, a recent discovery by scientists at the Harvard-Smithsonian Centre for Astrophysics has found that it is 17 times as dense – a bit like comparing a styrofoam ball with a bowling ball.

This means that it is dense and rocky, similar to Earth. “This is the Godzilla of Earths!” said Centre for Astrophysics researcher Dimitar Sasselov, director of the Harvard Origins of Life Initiative. “But unlike the movie monster, Kepler-10c has positive implications for life.”

Dense rocky planet
Planet hunters were surprised by the discovery of such a dense rocky planet, dubbed a “mega-Earth” because theoreticians say that a planet like this cannot exist.

Another researcher from the centre, David Latham, said: “The standard theory says that a planet first accumulates a core of rocky or dense materials: dust grains, pebbles, rocks … but once the core mass of the planet exceeds 10 times that of Earth, it’s a one-way street: [it is so heavy that] it pulls [the surrounding] gas to itself and makes a gas giant planet.”

Gas giants, such as Jupiter, are not conducive to life, as they generally comprise helium and hydrogen, rather than the heavy elements required for a planet such as Earth. They also do not have a “surface”, rather varying concentrations of gas.

But, perhaps more fundamentally, this Godzilla planet calls much of what we know about the evolution of planets into question.

Scientists at Nasa have estimated the age of the Kepler 10 system at about 11-billion years, about three billion years after the Big Bang. According to common ideas about the formation of rocky planets, Godzilla should not exist.

After the Big Bang, the universe was a swirl of hydrogen and helium, which coalesced into stars. Only once these stars had gone supernova – collapsing in on themselves to form the heavy elements that we associate with rocky planets – and then exploded outwards, could these rocky planets begin to form.

“We thought that you had to wait a few billion years to get rocky planets … [This discovery] pushes back the [time scale] for the possibility of planets where life might evolve,” Latham said.

Kepler-10c shows that the universe was able to form such huge rocks even during a time when heavy elements were scarce. “Finding Kepler-10c tells us that rocky planets could form much earlier than we thought. And if you can make rocks, you can make life,” said Sasselov.

But the researchers do not know whether Godzilla has life and the compact atmosphere required to support it. Latham said that they would have to wait for the next generation of instruments, such as the James Webb Space Telescope or the Square Kilometre Array, to be able to study Kepler-10c in that kind of detail.

Subscribe to the M&G

These are unprecedented times, and the role of media to tell and record the story of South Africa as it develops is more important than ever.

The Mail & Guardian is a proud news publisher with roots stretching back 35 years, and we’ve survived right from day one thanks to the support of readers who value fiercely independent journalism that is beholden to no-one. To help us continue for another 35 future years with the same proud values, please consider taking out a subscription.

Related stories

Government’s Covid-19 science mask is slipping

The government’s professed reliance on science to justify its response to the pandemic reveals both its overconfidence and its insecurities about getting citizens to cooperate

Inclusivity through innovation

Special Annual Theme Award: Materials for inclusive economic development

Why we need more women to work in water research

Investing more in women in science — particularly in the water and sanitation sectors — is imperative if we are to meet the sustainable development goals by 2030

African governments must invest in science for future growth

Allocating adequate funding to scientific research, development and innovation can have a positive effect on sustainable development

Build bond between science and society

New ideas and technologies can provide solutions but in unethical hands they can be dangerous

​All actions to counter climate change matter

Sipho Kings and Sarah Wild consider the question we all ask: Do our efforts count, or is this just about what big corporations do?

Subscribers only

Toxic power struggle hits public works

With infighting and allegations of corruption and poor planning, the department’s top management looks like a scene from ‘Survivor’

Free State branches gun for Ace

Parts of the provincial ANC will target their former premier, Magashule, and the Free State PEC in a rolling mass action campaign

More top stories

Vitamin therapy is for drips

It may be marketed by influencers, but intravenous vitamin therapy is not necessary and probably not worth the hype, experts say

Facebook, Instagram indiscriminately flag #EndSars posts as fake news

Fact-checking is appropriate but the platforms’ scattershot approach has resulted in genuine information and messages about Nigerians’ protest against police brutality being silenced

Murder of anti-mining activist emboldens KZN community

Mam’Ntshangase was described as a fierce critic of mining and ambassador for land rights.

Unite with Nigeria’s ‘Speak Up’ generation protesting against police brutality

Photos of citizens draped in the bloodied flag have spread around the world in the month the country should be celebrating 60 years of independence

press releases

Loading latest Press Releases…

The best local and international journalism

handpicked and in your inbox every weekday