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IN NUMBERS

Does the Solar System have a dark secret?
Researchers at the University of Edinburgh have
found that ‘dark hydrogen’ may be hidden under
the surface of gas giant planets such as Jupiter
and Saturn.
It is accepted that hydrogen exists as a gas on
the surface of giant planets and as liquid metal at
their core. But what lies in between?
To investigate this, the team used a laser-
heated diamond anvil to recreate conditions
found in the interior of gas giants. They
squeezed hydrogen to pressures up to 1.
million times of that on the Earth’s surface and
heated it up to 5,000°C. They found a point

between the gas and liquid phases at which the

hydrogen doesn’t absorb or reflect light, which

they dubbed ‘dark hydrogen’.

“A dark hydrogen layer in giant planets

separates the atmosphere and the metallic

interior, and neither reflects nor transmits visible

light, but does allow infrared radiation to pass,”

said researcher Stewart Williams. “This indicates

heat can easily escape from within giant planets.

The dark hydrogen layer also weakly conducts

electricity, allowing it to participate in the

production of the planetary magnetic field.”

The finding may help researchers to

understand how gas giants form.

MYSTERIOUS ‘DARK HYDROGEN’

MAY BE LURKING INSIDE GAS GIANTS

On gas giants,

hydrogen may

exist in three

different forms: as

a gas, as a liquid

and as ‘dark

hydrogen’

999%

The proportion of the Earth’s

one trillion microbial species

yet to be discovered, as

estimated by a biologist at

Indiana University.

89.5m

The height of the world’s

tallest tree: a yellow meranti

discovered in the Malaysian

rainforest by researchers at

Cambridge University.

The number of litres of

helium found in a gas field

in Tanzania. The discovery

will help to combat the world

shortage of the gas, which is

used in everything from

MRI scanners to deep-sea

diving equipment.

trillion

15

SPACE