2019-06-22_New_Scientist

News

Exomoons

Leah Crane

ABOUT 370 light years away, a

planet is being born, possibly with its

own set of rings or moons. In 2018,

astronomers spotted a young world

growing around star PDS 70. Now

they have observed what appears

to be a disc of debris orbiting the

planet, the same sort of disc that

we think can coalesce into a moon.

Faustine Cantalloube at the Max

Planck Institute for Astronomy

in Heidelberg, Germany, and his

colleagues used the Very Large

Telescope in Chile to examine the

spectrum of light coming from the

planet, PDS 70b, and found that

it appeared to be emitting more

infrared light than we would expect

for a planet alone.

The infrared light indicates that

something above the planet’s

surface is being heated as it absorbs

light from the planet and re-emits it

at a longer and redder wavelength.

The team compared the data with

models that included a planetary

atmosphere or a disc of dust and

gas, and found that the disc was a

far better match (The Astrophysical

Journal Letters, doi.org/c698).

“The planet is very young,

so it’s hot and bright and it’s

heating up this dust around the

planet,” says Cantalloube.

This is the first time we have

spotted a disc around a young

planet. Some material from the disc

is probably falling onto the planet

and helping it grow, but eventually

the disc may flatten out to form

rings like Saturn’s or clump up and

create moons. We have never before

definitively spotted a moon around

a planet outside our solar system. ❚

The live birth

of a planet and

its moons

Adam Vaughan

THE UK is to set itself the most

ambitious long-term climate

target of any major country: to

become carbon neutral by 2050.

It is being seen by many as a

bid by outgoing prime minister

Theresa May to build a legacy

beyond Brexit. “Now is the

time to go further and faster

to safeguard the environment

for our children,” she said in

a statement last week.

The net zero target is a

dramatic raising of ambition

from the existing UK target of

an 80 per cent cut in emissions

by 2050. Under net zero, some

industries are likely to still emit

carbon by mid-century, but

these would be offset by other

measures, such as tree planting,

that suck carbon from the air.

The decision to push ahead

with the tougher goal comes

despite grumbles about it from

parts of the government. Earlier

this month, the Treasury said

that moving to net zero would

cost in excess of £1 trillion by

2050 – more than government

advisers had said – and the

implications should be better

understood before enacting the

target. In an apparent nod to

these concerns, Downing Street

promised a review within five

years, to see if other countries

are taking similar action and

to check that “industries do

not face unfair competition”.

Boris Johnson and Jeremy

Hunt, two of the frontrunners in

the race to lead the Conservative

party and become the UK’s next

prime minister, have both said

they support the new goal.

It was also welcomed by the

government’s adviser on global

warming, the Committee on

Climate Change (CCC), which

had called for the stricter target

in May. And it follows months

of protests by school pupils and

campaigners calling for tougher

action (see “Do protests work?,

page 20). The Confederation of

British Industry also says it is

“the right response to the...

climate crisis”.

However, the government

says it would “retain the ability

to use international carbon

credits”. This can involve paying

other countries to make carbon

cuts on the UK’s behalf to count

towards the target. The CCC

advises against this, saying the

target should be met within the

UK’s borders.

The goal has been introduced

as a draft amendment to the

Climate Change Act 2008, but

MPs will need to vote for the

measure before it becomes law.

Only three MPs voted against

the original law 11 years ago.

One way to get close to net

zero by 2050 would be to replace

natural gas with hydrogen.

A report by the Institution of

Engineering and Technology

last week concluded that using

hydrogen for heating, power

and industry would be safe.

However, the report revealed

that this would require a hike

in hydrogen production to

10 times current levels.

Norway also made climate

moves last week, with its MPs

backing a decision to divest the

country’s $1 trillion sovereign

wealth fund from oil and gas

exploration firms and invest

more in renewable energy.

The fund, known formally as

the Government Pension Fund

Global, will gradually sell off an

$8 billion stake in 134 oil and

gas firms. But the shift will only

affect companies solely involved

in fossil fuel exploration, not

those such as Shell and BP

which also have renewable

energy business arms. ❚

UK raises climate goal to

net zero carbon by 2050

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Protesters want

more drastic

action on emissions

11

years since the UK’s last major

climate change legislation

Climate policy

Planet PDS 70b

(the light circle)

is forming in the

protoplanetary

disc of star

PDS 70

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10 | New Scientist | 22 June 2019