of our solar system. At last count, we have
identified 3,538.
Out of the thousands of planets we know about,
some of them are incredibly bizarre compared to
what we are used to seeing in our own solar
system. Here are some exoplanets with very
unique characteristics:
Kepler-78b
The most astounding fact about Kepler-78b is
that it shouldn’t even exist, according to our
current knowledge of planetary formation. It is
extremely close to its star at only 550,000 miles
(900,000 kilometers). As a comparison, Mercury
only gets within 28.5 million miles (45.9 million
kilometers) of the sun in the nearest point of
orbit. With that proximity, it isn’t clear how the
planet could have formed as the star was much
larger when the planet formed. With its current
distance, that would mean it formed inside the
star, which is impossible as far as we know.
The planet itself is only slightly larger than Earth,
though surface conditions are markedly different.
The temperature on the surface is estimated to be
4300° F (2400° C), which is nearly nine times as
hot as the temperature on Venus. Unfortunately
for Kepler-78b, it is likely that the star’s
gravitational pull will gradually bring the star
closer and totally consume it in the next 3 billion
years.
WASP-12b
While Kepler-78b still has about 3 billion more
years before getting consumed by its star, the
process is well underway for WASP-12b . This
exoplanet is actively getting pulled apart by its
parent star, much to the delight of astronomers
who can watch the process unfold. So much
material has been pulled away from the planet, it
has been pulled into an oblong football shape.
Astronomers have estimated that WASP-12b has
about 10 million more years until it is completely
pulled apart by the star.
The planet is described as a “hot Jupiter” as it is
a gas planet that is about 40 percent larger than
Jupiter. It is currently so close to its star that it
only takes 1.1 Earth days for the planet to
complete a full orbit. The star, WASP-12, is G-
type main sequence star, just like our own sun. It
is located about 800 lightyears away in the Auriga
constellation.
TrES-2b
TrES-2b has been dubbed the “dark planet”
because it does not reflect light. If we were able
to view it directly, it would likely just look like a
coal-black ball of gas. At 1800°F (1000°C) the
planet is way too hot for clouds, which would
help reflect the star’s light. The red tinges are
areas of superheated gas. Other darker planets
only reflect about 10% of the star’s light, but
TrES-2b only reflects about 1%, making it the
darkest planet ever discovered.
Why is TrES-2b so dark? Scientists aren’t quite
sure. Right now, the best guess is that the
majority of the planet’s composition is something
like sodium or potassium which absorbs light.
This dark world is located about 750 lightyears
away in the Draco constellation.
HD 189773b
HD 189773b is pretty exciting. It is relatively
close, at only 63 lightyears away. It is also the
first planet to have its color determined and it
turned out to be a pretty blue planet, just like
Earth. Unlike Earth, however, HD 189773b is a
gas giant with a temperature that reaches a
sweltering 1800°F (1000°C). The weather gets
more extreme, because intense pressure and
temperature turns silicate particles in the
atmosphere into glass, which then rains down. As
if that doesn’t sound dangerous enough, the
winds have been estimated to gust at 4,000 mph
(7,000 km/h) which really whips those glass
particles around.
55 Cancri e
55 Cancri e is twice the size of Earth but is nearly
8 times more massive and twice as dense. Last
fall, researchers deduced that the mass of the
planet was largely carbon. Due to the pressure
and surface temperature of 4892°F (2700°C) it
very well could have formed diamond. It is so
close to its parent star it takes a mere 18 hours
for the planet to complete a full orbit.
55 Cancri e is only about 40 light-years away
from us in the Cancer constellation. The parent
star is much more carbon than our own sun, so it
might be too surprising that planet e is also
carbon-rich. From there, it isn’t much of a stretch
to assume that the other four known planets in
the system would also have a high carbon
content.
Because of these extreme conditions, astronomers
don’t believe that 55 Cancri e has an atmosphere,
making it a poor candidate for the possibility for
life. However, it is close enough for astronomers
to use it to test hypotheses about planetary
formation.
PSR B1620-26b
Nicknamed “Methuselah,” PSR B1620-26b is the
oldest known exoplanet. The planetary system
formed approximately 12.7 billion years ago, when
the Milky Way galaxy was in its infancy. It is
located in the Scorpius constellation about 12,400
lightyears away.
Methuselah orbits binary stars and goes around
them in a circumbinary orbit. As if Methuselah’s
age isn’t interesting enough, the fact that it orbits
two mismatched dead stars is quite unusual. One
of the stars is a pulsar and the other is a white
dwarf. Since Methuselah is found in a dense star
cluster, astronomers initially thought it could be a
star as well, and would be considered a brown
dwarf. Measurements from the Hubble would
confirm that Methuselah is a planet, and it
remains the oldest one we’ve ever discovered.
TrES-4
Located 1,400 lightyears away in the Hercules
constellation, TrES-4 is the largest exoplanet we
have discovered so far. Though it is over 1.7
times the size of Jupiter, it has an extremely low
density and is categorized as a “puffy” planet.
The planet’s density is about the same as cork,
which came as quite a shock. Astronomers
attribute this to extreme heat of 2,300° F (1,260°
C) due to is proximity to the star. At only 4.5
million miles (7.2 million kilometers) away from
its sun, TrES-4 is able to complete an orbit in
three Earth days.
Gliese 436 b
30 lightyears away in the constellation Leo, Gliese
436 b is a planet that is about as massive as
Neptune. The planet also happens to be covered
in burning ice - though the ice isn’t anything like
what we’re used to. The extreme pressure of the
planet forces the water to stay in solid form, even
though the temperature exceeds 570° F (300° C).
The outer layer of the solid water is superheated
and comes off as vapor. Water has over 10 solid
states, not including common ice.
In its present position, the water would not have
been able to condense down into a solid,
indicating that it migrated toward its sun after it
formed.


