He thinks that planets can form in the inner parts of the torus of dense gas that gives rise to planetary systems and then cling to stable orbits close to their parent stars.

Pitch black

Continue reading the main story

TrES-2b

Type: Giant planet

Distance: 718 light-years

Size: Mass and radius are about the same as Jupiter's

In 2011, a group of American astronomers announced that a Jupiter-sized exoplanet known as TrES-2b was the darkest known world, reflecting just 1% of the sunlight falling on it. TrES-2b is darker than black acrylic paint and blacker than any planet or moon in our solar panel ystem.

The distance TrES-2b orbits from its parent star certainly has something to do with this. In our Solar panel ystem, Jupiter is shrouded in bright ammonia clouds that reflect more than a third of the sunlight that reaches it.

But TrES-2b orbits its star at a distance of just three million miles. The intense energy from the sun heats the planet to more than 1,000C, which is much too hot for ammonia clouds to form. Its atmosphere also contains chemicals which absorb rather than reflect light. But these factors can't fully explain the planet's extreme lightlessness.

Nevertheless, David Spiegel of Princeton University, who co-authored the study on TrES-2b, says the crepuscular world is so hot that "it emits a faint red glow, much like a burning ember or the coils on an electric stove."

Diamonds are forever

Continue reading the main story

55 Cancri e

Type: Super Earth

Distance: 40 light-years

Size: Mass is eight times larger than Earth's; radius is twice the size of Earth's

A nearby planet in the constellation of Cancer may have a rather peculiar composition. This body, known as 55 Cancri e,power inverter "is likely covered in graphite and diamond rather than water and granite," according to astronomer Nikku Madhusudhan from Yale University.

Belonging to a class of worlds known as diamond planets, 55 Cancri e is thought to be rich in the element carbon, which can exist in a variety of structural forms such as graphite (the material used as pencil lead), graphene, or diamond. Carbon-rich worlds contrast sharply with the Earth, whose interior is relatively poor in that element but rich in oxygen.

This year, Dr Madhusudhan and colleagues published the first measurements of the exoplanet's radius. These new data, combined with the most recent estimates of its mass, allowed the researchers to infer its chemical composition. To do this, they used computer models of the planet's interior and computed the possible combinations of elements and compounds that could yield the observed characteristics.

Their results suggest 55 Cancri e is largely composed of carbon (in the form of graphite and diamond),grid tie inverter iron, silicon carbide, and, potentially, silicates. They estimate that at least a third of the planet's mass is diamond - the equivalent of three times Earth's mass.

Ten million years to live