Five Extraordinary Exoplanets
Exoplanet visualisation. Credit: NASA

Five Extraordinary Exoplanets

31/03/2021Written by Alex Thompson

For the past three decades scientists have been able to look further into our Universe, not just at stars but at exoplanets too.

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Credit: NASA

Although the first possible existence of a planet outside our Solar System was noted in 1917, orbiting the white dwarf Van Maanen 2, it was not until 1992 that we saw the first confirmed discovery of extrasolar planets, with several terrestrial-mass planets orbiting the pulsar PSR B1257+12.

In 1995 the gas giant 51 Pegasi b became the first exoplanet orbiting a main-sequence star to have its existence confirmed.

Some exoplanets have been imaged directly by telescopes, but the vast majority have been detected through indirect methods, such as the transit method and the radial-velocity method.

  • Transit method – the detection of a dip in the brightness of a distant star due to the orbit of another object.
  • Radial-velocity method – (also known as Doppler spectroscopy) the detection of movement of a star due to the gravitational pull of an orbiting object.

As of 1 March 2021, there are 4,687 confirmed exoplanets in 3,463 systems, with 770 systems having more than one planet.

Here are five of the most amazing exoplanets found to date.

55 Cancri e – a super-hot super-Earth

55 Cancri e – a super-hot super-Earth

Credit: NASA

At around twice the size of Earth, 55 Cancri e the first super-Earth discovered around a main sequence star.

Orbiting its host star, 55 Cancri A, at a distance twenty-five times closer than Mercury is to our Sun, 55 Cancri e is toasty to say the least.

It’s so close to its star that it only takes 18 hours to complete an orbit and is tidally locked, meaning that whilst one side is always in complete darkness the other must permanently suffer unimaginable heat.

The temperature facing its sun reaching over 2300°C, whilst the cooler side reaches a modest 1400°C.

Despite these incredible temperatures scientists believe that 55 Cancri e could have similarities with Earth.

Although it is twice the size of our home planet, the density is similar, which indicates it may be rocky. Experts also believe that its size indicates it has an atmosphere, as it would have to be far larger if there was none. This atmosphere could contain nitrogen, water and even oxygen – not that we’re suggesting life could withstand such heat, or the lava lakes that possibly run throughout its surface.

However, its not all bad, as the large amount of carbon and high temperatures has the potential to create diamonds.

Kepler-16b – the real-life Star Wars planet

Kepler-16b – the real-life Star Wars planet

Credit: NASA

Anybody who has ever watched the early Star Wars movies will know that George Lucas was ahead of his time as a movie maker, but was he also over three decades ahead of scientists with the discovery of Kepler-16b in a genuine case of life imitating art?

Of course Kepler-16b is far older than the science fiction franchise, but it was not until 2011 it became the first exoplanet in a binary star system to be discovered.

This means that it orbits two moons instead of one, making it very similar to the Tatooine planet that was home to Luke Skywalker in A New Hope, the original Star Wars film.

Kepler-16b is a cold gaseous world, consisting of half gas and half rock and ice, that exists outside of its system’s habitable zone and was discovered using the space observatory aboard NASA’s Kepler spacecraft.

WASP 12b – the doomed exoplanet

WASP 12b – the doomed exoplanet

Artist's concept of the exoplanet WASP-12b. Credit: NASA

A planet on a journey towards its own slow destruction at the hands of its own sun, the gas giant WASP 12b can hit temperatures of over 2200°C (scarf and jumper weather by 55 Cancri e standards).

Like Cancri 55 e, WASP 12b is orbiting so close to the yellow dwarf star WASP-12, that it is being torn apart by tidal forces caused by gravity.

Using the Hubble Telescope, scientists have been able to observe that the planet is being pulled into the shape of an egg, and they estimate the star will consume it within the next ten million years.

WASP-12b is known as a ‘hot Jupiter’, a class of gas giant exoplanets that are  similar to Jupiter, have very short orbital periods, close proximity to their stars and high surface-atmosphere temperatures.

GJ-504b – the pink planet

GJ-504b – the pink planet

Artists impression of GJ 504b Credit: NASA

Thought to be one of the oldest extrasolar planet directly imaged, GJ-504b is the lowest-mass exoplanet ever discovered around a Sun-like star using direct imaging techniques.

It is still glowing from the heat of its formation, around 160 million years ago, with a colour that is best described by NASA as “dark cherry blossom” (we think that may be in the Valspar range this summer).

However, the most intriguing thing about GJ-504b has experts questioning the way we understand the formation of giant planets.

GJ-504b is around the same size of Jupiter (though four times the mass), a planet we know was formed from gas-rich leftovers of the Sun. Based on this, we would expect GJ-504b to form at a similar distance from its star, however, that is not the case.

In fact it is around nine times further than Jupiter is from our Sun. Discoveries such as this make scientists question the theories they have long accepted as fact.

HD 189773b – the ‘rains of terror’ exoplanet

HD 189773b – the ‘rains of terror’ exoplanet

Artists impression. Credit: NASA

Another ‘hot Jupiter’ exoplanet, this one comes with a warning as one of the most harrowing and deadly exoplanets ever discovered.

The image distributed by NASA shows an artists impression of a beautiful blue planet, that you may be fooled into believing is a picture of an ocean covered world, however, looks can be deceiving.

In reality it is actually the reflection of silicate, which, when heated to the exoplanet’s temperature of 1300°C, forms grains of glass which fall to the planet’s surface.

When we say ‘fall’ we actually mean ‘blown by a ferocious 5200mph winds’, seven times the speed of sound, which combine to provide the ultimate holiday experience – death by a thousand cuts.