25 Weirdest Facts About the Solar System
Our place in space.
The solar system is a bizarre place with its alien planets, mysterious moons and strange
phenomena that are so out-of-this-world they elude explanation.
Scientists have discovered ice-spewing volcanoes on
Pluto, while Mars is home to a truly "grand" canyon the size of the United States.
There may even be a giant,
undiscovered planet lurking somewhere beyond Neptune.
Read on to find out some of the strangest facts about planets,
dwarf planets, comets and other incredible objects around the solar system.
1.
Uranus is tilted on its side.
Uranus appears to be a featureless blue ball upon first glance, but this gas giant
of the outer solar system is pretty weird upon closer inspection.
First, the planet rotates on its side for reasons
scientists haven't quite figured out.
The most likely explanation is that it underwent some sort of one or more
titanic collisions in the ancient past.
In any case, the tilt makes Uranus unique among the solar system planets.
Uranus also has tenuous rings, which were confirmed when the planet passed in front
of a star (from Earth's
perspective) in 1977; as the star's light winked on and off repeatedly, astronomers
realized there was more than
just a planet blocking its starlight.
More recently, astronomers spotted storms in Uranus' atmosphere several years
after its closest approach to the sun, when the atmosphere would have been heated the
most.
2.
Jupiter's moon Io has towering volcanic eruptions.
For those of us used to Earth's relatively inactive moon, Io's
chaotic landscape may come as a huge surprise.
The Jovian moon has hundreds of volcanoes and is considered the most
active moon in the solar system, sending plumes up to 250 miles into its atmosphere . Some
spacecraft have caught
the moon erupting; the Pluto-bound New Horizons craft caught a glimpse of Io bursting when
it passed by in 2007.
Io's eruptions come from the immense gravity the moon is exposed to, being nestled in Jupiter's
gravitational well.
The moon's insides tense up and relax as it orbits closer to, and farther from, the planet,
generating enough energy
for volcanic activity.
Scientists are still trying to figure out how heat spreads through Io's interior, though,
making it difficult to predict where the volcanoes exist using scientific models alone.
3.
Mars has the biggest volcano (that we know of).
While Mars seems quiet now, we know that in the past something
caused gigantic volcanoes to form and erupt.
This includes Olympus Mons, the biggest volcano ever discovered in the
solar system.
At 374 miles (602 km) across, the volcano is comparable to the size of Arizona.
It's 16 miles (25
kilometers) high, or triple the height of Mount Everest, the tallest mountain on Earth.
Volcanoes on Mars can grow
to such immense size because gravity is much weaker on the Red Planet than it is on Earth.
But how those volcanoes
came to be in the first place is not well known.
There is a debate as to whether Mars has a global plate tectonic
system and whether it is active.
4.
Mars also has the longest valley.
If you thought the Grand Canyon was big, that's nothing compared to Valles
Marineris.
At 2,500 miles (4,000 km) long, this immense system of Martian canyons is more than 10
times as long as
the Grand Canyon on Earth.
Valles Marineris escaped the notice of early Mars spacecraft (which flew over other parts
of the planet) and was finally spotted by the global mapping mission Mariner 9 in 1971.
And what a sight it was to
miss — Valles Marineris is about as long as the United States!
The lack of active plate tectonics on Mars makes it
tough to figure out how the canyon formed.
Some scientists even think that a chain of volcanoes on the other side of
the planet, known as the Tharsis Ridge, somehow bent the crust from the opposite side of Mars,
thus creating Valles
Marineris.
More close-up study is needed to learn more, but you can't send a rover over there easily.
5.
Venus has super-powerful winds.
Venus is a hellish planet with a high-temperature, high-pressure environment on
its surface.
Ten of the Soviet Union's heavily shielded Venera spacecraft lasted only a few minutes
on its surface
when they landed there in the 1970s.
But even above its surface, the planet has a bizarre environment.
Scientists
have found that its upper winds flow 50 times faster than the planet's rotation.
The European Venus Express
spacecraft (which orbited the planet between 2006 and 2014) tracked the winds over long
periods and detected
periodic variations.
It also found that the hurricane-force winds appeared to be getting stronger over time.
6.
There is water ice everywhere.
Water ice was once considered a rare substance in space, but now we know we just
weren't looking for it in the right places.
In fact, water ice exists all over the solar system.
Ice is a common
component of comets and asteroids, for example.
But we know that not all ice is the same.
Close-up examination of
Comet 67P/Churyumov–Gerasimenko by the European Space Agency's Rosetta spacecraft, for example,
revealed a different
kind of water ice than what is found on Earth.
That said, we've spotted water ice all over the solar system.
It's in
permanently shadowed craters on Mercury and the moon, although we don't know if there's
enough to support colonies
in those places.
Mars also has ice at its poles, in frost and likely below the surface dust.
Even smaller bodies in
the solar system have ice – Jupiter's moon Europa, Saturn's moon Enceladus, and the dwarf
planet Ceres, among
others.
7.
Spacecraft have visited every planet.
We've been exploring space for more than 60 years, and have been lucky
enough to get close-up pictures of dozens of celestial objects.
Most notably, we've sent spacecraft to all of the
planets in our solar system — Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune
— as well as two
dwarf planets, Pluto and Ceres.
The bulk of the flybys came from NASA's twin Voyager spacecraft, which left Earth in
1977 and are still transmitting data from beyond the solar system in interstellar space.
Between them, the Voyagers
clocked visits to Jupiter, Saturn, Uranus and Neptune, thanks to an opportune alignment
of the outer planets.
8.
There could be life in the solar system, somewhere.
So far, scientists have found no evidence that life exists
elsewhere in the solar system.
But as we learn more about how "extreme" microbes live in underwater volcanic vents
or in frozen environments, more possibilities open up for where they could live on other
planets.
These aren't the
aliens people once feared lived on Mars, but microbial life in the solar system is a possibility.
Microbial life is
now considered so likely on Mars that scientists take special precautions to sterilize spacecraft
before sending
them over there.
That's not the only place, though.
With several icy moons scattered around the solar system, it's
possible there are microbes somewhere in the oceans of Jupiter's Europa, or perhaps underneath
the ice at Saturn's
Enceladus, among other locations.
9.
Mercury is still shrinking.
For many years, scientists believed that Earth was the only tectonically active
planet in the solar system.
That changed after the Mercury Surface, Space Environment, Geochemistry and Ranging
(MESSENGER) spacecraft did the first orbital mission at Mercury, mapping the entire planet
in high definition and
getting a look at the features on its surface.
In 2016, data from MESSENGER (which had crashed into Mercury as
planned in April 2015) revealed cliff-like landforms known as fault scarps.
Because the fault scarps are relatively
small, scientists are sure that they weren't created that long ago and that the planet
is still contracting 4.5
billion years after the solar system was formed.
10.
There are mountains on Pluto.
Pluto is a tiny world at the edge of the solar system, so at first it was thought
that the dwarf planet would have a fairly uniform environment.
That changed when NASA's New Horizons spacecraft flew
by there in 2015, sending back pictures that altered our view of Pluto forever.
Among the astounding discoveries
were icy mountains that are 11,000 feet (3,300 meters) high, indicating that Pluto must have
been geologically
active as little as 100 million years ago.
But geological activity requires energy, and the source of that energy
inside Pluto is a mystery.
The sun is too far away from Pluto to generate enough heat for geological activity, and
there are no large planets nearby that could have caused such disruption with gravity.
11.
Pluto has a bizarre atmosphere.
Pluto's observed atmosphere broke all the predictions.
Scientists saw the haze
extending as high as 1,000 miles (1,600 km), rising higher above the surface than the atmosphere
on Earth.
As data
from New Horizons flowed in, scientists analyzed the haze and discovered some surprises there,
too.
Scientists found
about 20 layers in Pluto's atmosphere that are both cooler and more compact than expected.
This affects calculations
for how quickly Pluto loses its nitrogen-rich atmosphere to space.
NASA's New Horizons team found that tons of
nitrogen gas escape the dwarf planet by the hour, but somehow Pluto is able to constantly
resupply that lost
nitrogen.
The dwarf planet is likely creating more of it through geological activity.
12.
Rings are everywhere in the solar system.
While we've known about Saturn's rings since telescopes were invented
in the 1600s, it took spacecraft and more powerful telescopes built in the last 50 years
to reveal more.
We now know
that every planet in the outer solar system – Jupiter, Saturn, Uranus and Neptune – each
have ring systems.
That
said, rings are very different from planet to planet.
Saturn's spectacular rings, which may have come from a
broken-up moon, are not repeated anywhere else.
Rings aren't limited to planets, either.
In 2014, for example,
astronomers discovered rings were discovered around the asteroid Chariklo.
Why such a small body would have rings is
a mystery, but one hypothesis is perhaps a broken-up moonlet created the fragments.
13.
Jupiter's Great Red Spot is shrinking.
Along with being the solar system's largest planet, Jupiter also hosts
the solar system's largest storm.
Known as the Great Red Spot (since it's big and ruddy-colored), it's been observed
in telescopes since the 1600s.
Nobody knows exactly why the storm has been raging for centuries, but in recent
decades another mystery emerged: the spot is getting smaller.
In 2014, the storm was only 10,250 miles (16,500 km)
across, about half of what was measured historically.
The shrinkage is being monitored in professional telescopes
and also by amateurs, as telescope and computer technology allow high-powered photographs
at an affordable cost.
Amateurs are often able to make more consistent measurements of Jupiter, because viewing time
on larger,
professional telescopes is limited and often split between different objects.
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