We may have discovered hundreds of exoplanets, but this new alien world is one of the weirdest
yet.
Hello!
I’m Ian O’Neill, space producer for Discovery News and I have a confession -- I’m a bit
of an exoplanet addict.
I’m fascinated by every exoplanet discovery -- we live in an incredible age where we can
see worlds of all sizes orbiting stars many light-years away.
This is all part of an exciting quest to ultimately track down a world with similar qualities
to Earth.
I’m my lifetime I hope that astronomers will discover a true Earth-like world that
we are able to probe its atmosphere and find possible biosignatures.
In other words: finding a world that could host a life-giving alien biosphere.
The event of finding a truly habitable alien world may be a long way off, but for now we
have missions like NASA’s Kepler Space Telescope doing mindblowing work detecting small worlds,
big worlds and worlds that are just plain WEIRD.
And this latest exoplanet discovery definitely falls into the “weird” category.
Kepler-432b is the densest exoplanet discovered to date with a mass of SIX times that of Jupiter,
but with all that mass jammed into a planet of Jupiter’s size.
But how do you go about measuring the mass of a planet that is nearly 3,000 light-years
away?
First detected by NASA’s Kepler space telescope in 2014, the mission was able to measure the
planet’s physical size by gauging how much light of its host star would dim each time
it orbited in front.
These dimming events are known as “transits” and they can be used to work out the size
and orbital period of distant worlds.
But to measure the planet’s mass, astronomers using two Spanish ground based observatories
measured the slight “wobble” of the star as that planet orbited.
The more massive the planet, the greater its gravitational effects and the greater the
star’s wobble.
This type of observation is known as the “radial velocity” method.
When observed over a long period, a precise measurement of the planet’s mass can be
recorded.
By combining data from transit and radial velocity methods, it’s a fairly simple calculation
to arrive at the planet’s density, combining the mass and size.
And it just so happens that this is one seriously dense planet.
But its density isn’t the only thing that makes Kepler-432b unique -- it also has one
of the most eccentric -- or stretched -- orbits of all the exoplanets discovered to date.
During the 52 day orbit around its star, the world suffers some extreme seasonal heating.
At its furthest orbital point, the exoplanet is a hot 1000 degrees Fahrenheit, but at its
closest approach, it bakes to over 1800 degrees.
Its orbit is a clue as to why we don’t see these kinds of exoplanets very often.
Kepler-432b is a world with an expiration date.
Its host star is a huge red giant that is undergoing its final death throes after running
out of hydrogen fuel in its core.
It is predicted to become so puffed up that its scorching plasma will likely swallow the
unfortunate exoplanet in around 200 million years time.
Therefore, Kepler-432b is a planet of extremes.
It’s extremely dense; it has a hellish rollercoaster orbit and it is destined to be destroyed by
a stellar blowtorch in the not-so-distant future.
Although this is one world certainly not suitable for life as we know it, it’s yet another
reminder about how rich and diverse our galaxy is, filled with exoplanets that are very different
to the planets contained within our own solar system.