From its discovery in the depths of space, to what makes it special in terms of composition,
and more!
Allow us to show you Ariel Uranus Brightest Moon.
10.
The Discovery of Ariel In terms of its finding, Ariel was discovered
on October 24, 1851 by William Lassell, it is named for a sky spirit in an Alexander
Pope's story and Shakespeare's The Tempest.
Which is not too uncommon given the power that literature and mythology have in regards
to naming things like this.
Both Ariel and the slightly larger Uranian satellite Umbriel were discovered by William
Lassell on the same day believe it or not.
Although William Herschel, who discovered Uranus's two largest moons Titania and Oberon
in 1787, claimed to have observed four additional moons, this was never confirmed and those
four objects are now thought to be spurious.
If you look at the history of finding planets and moons you'll find similar stories of astronomers
trying to get credit because of believed discoveries.
All of Uranus's moons are named after characters from the works of William Shakespeare or Alexander
Pope.
The names of all four satellites of Uranus then known were suggested by John Herschel
in 1852 at the request of Lassell.
Ariel is named after the leading sylph in one of Pope's stories.
It is also the name of the spirit who serves Prospero in Shakespeare's The Tempest.
The moon is also designated Uranus I.
Which is a more generalized title to help show which moons were discovered in what order
and is a common thing across multiple moons of various planets.
9.
Its Surface All of Uranus' larger moons, including Ariel,
are thought to consist mostly of roughly equal amounts of water ice and silicate rock.
Carbon dioxide has also been detected on Ariel.
Which is important in helping determine various things about the moon itself.
Ariel's surface appears to be the youngest of all the moons of Uranus.
That is believed because it has few large craters and many small ones, indicating that
fairly recent low-impact collisions wiped out the large craters that would have been
left by much earlier, bigger strikes.
You might think, "but why does that matter?"
Scientists like to use impact craters to help determine certain things about the surface,
as well as indications of where to look for materials of asteroids or meteors that might
have pelted the surface of certain moons or planets.
Because getting samples of them can help tell a timeline for various things, including the
history of the planet.
Ariel is also thought to have had the most recent geologic activity of Uranus' larger
moons.
It is transected by grabens, which are fault-bounded valleys.
Ariel has the brightest surface of the five largest Uranian moons, but none of them reflect
more than about a third of the sunlight that strikes them.
This suggests that their surfaces have been darkened by a carbonaceous material.
Ariel's brightness increases dramatically when it is in opposition―that is, when the
observer is directly between it and the Sun.
This indicates that its surface is porous, casting reflectivity-decreasing shadows when
illuminated at other angles.
This is another curious thing that scientists like to study, as it can help determine how
the moon came to be and the events that led to its current form.
8.
Rotations and Orbits Among Uranus's five major moons, Ariel is
the second closest to the planet, orbiting at the distance of about 190,000 km, or over
118,000 miles.
Its orbit has a small eccentricity and is inclined very little relative to the equator
of Uranus.
Its orbital period is around 2.5 Earth days, coincident with its rotational period.
This means that one side of the moon always faces the planet; a condition known as tidal
lock.
Which is a key thing in regards to temperature (more on that later).
Ariel's orbit lies completely inside the Uranian magnetosphere.
The trailing hemispheres (those facing away from their directions of orbit) of airless
satellites orbiting inside a magnetosphere like Ariel are struck by magnetospheric plasma
co-rotating with the planet.
This bombardment may lead to the darkening of the trailing hemispheres observed for all
Uranian moons except Oberon . Ariel also captures magnetospheric charged particles, producing
a pronounced dip in energetic particle count near the moon's orbit observed by Voyager
2 in 1986.
7.
Observation and Exploration The only close-up images of Ariel were obtained
by the Voyager 2 probe (one of the most important scientific tools in the history of the space
program), which photographed the moon during its flyby of Uranus in January 1986.
The closest approach of Voyager 2 to Ariel was 127,000 km (79,000 mi)—significantly
less than the distances to all other Uranian moons except Miranda.
The best images of Ariel have a spatial resolution of about 2 km.
They cover about 40% of the surface, but only 35% was photographed with the quality required
for geological mapping and crater counting.
Meaning that there is a lot more to learn from the surface of the moon.
At the time of the flyby the southern hemisphere of Ariel (like those of the other moons) was
pointed towards the Sun, so the northern (dark) hemisphere could not be studied.
No other spacecraft has ever visited the Uranian system.
The possibility of sending the Cassini spacecraft to Uranus was evaluated during its mission
extension planning phase.
It would have taken about twenty years to get to the Uranian system after departing
Saturn, and these plans were scrapped in favour of remaining at Saturn and eventually destroying
the spacecraft in Saturn's atmosphere.
What this means on the whole is that there could be a chance to go and try and do a closer
flyby for the moon should the opportunity arise.
Especially with the desire to further go and explore our solar system growing with every
year as we potentially get closer to sending a craft to Mars and other potentially viable
spots in the solar system.
If done correctly, it might not just go and help explore Ariel, but also, explore the
other moons of Uranus.
But whether this actually happens is up for debate.
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6.
Atmosphere Despite there being carbon dioxide on the
moon of Ariel in some capacity, there is no detectable atmosphere or magnetosphere that
we can find.
While this may on the surface sound like an ok thing, it's honestly not.
Because when you want to look for a place to live in the universe, an atmosphere is
preferable for a variety of reasons.
Without it and the Magnetic Field that means that not only will anything on the surface
be open to getting hit by various cosmic rays, it makes it all the more likely that asteroids
and meteors will bombard the place.
Which, if you recall, is something we know happens on Ariel, especially with the smaller
space rocks.
Now, to be clear, this doesn't make it the most uninhabitable place ever, but it's a
major deterrent in terms of explorations and wanting to go there for one reason or another
to colonize.
5.
Surface Temperature Measurements have shown that Ariel's surface
temperature rises and falls quickly with the coming and going of sunlight, without a "thermal
inertia" lag.
That supports the picture of a porous surface, which would tend to insulate the moon and
keep the subsurface from heating up.
This texture could be the result of eons of micrometeorite strikes tilling the soil.
In an earlier time, Ariel appears to have undergone enough heating to allow differentiation―a
separation in which heavier material sinks toward the core and lighter material "floats"
at or near the surface.
Models indicate that tidal interactions with Uranus may provide an important source of
heat.
But whether that heat is enough to do certain things, including live on the surface by channeling
that heat, is up for debate.
But given how the moon is in tidal lock and that the temperatures rise and fall...it's
unlikely.
4.
Seasons Because Ariel, like Uranus, orbits the Sun
almost on its side relative to its rotation, its northern and southern hemispheres face
either directly towards or directly away from the Sun at the solstices.
This means it is subject to an extreme seasonal cycle; just as Earth's poles see permanent
night or daylight around the solstices, so Ariel's poles see permanent night or daylight
for half a Uranian year (42 Earth years), with the Sun rising close to the zenith over
one of the poles at each solstice.
The Voyager 2 flyby coincided with the 1986 southern summer solstice, when nearly the
entire northern hemisphere was dark.
Once every 42 years, when Uranus has an equinox and its equatorial plane intersects the Earth,
mutual occultations of Uranus's moons become possible.
A number of such events occurred in 2007–2008, including an occultation of Ariel by Umbriel
on 19 August 2007.
3.
Composition Ariel is the fourth largest of the Uranian
moons, and may have the third greatest mass.
Its density indicates that it consists of roughly equal parts water ice and a dense
non-ice component.
Which could consist of rock and carbonaceous material including heavy organic compounds
known as tholins.
The presence of water ice is supported by infrared spectroscopic observations, which
have revealed crystalline water ice on the surface of the moon, which is porous and thus
transmits little solar heat to layers below.
Water ice absorption bands are stronger on Ariel's leading hemisphere than on its trailing
hemisphere.
The cause of this asymmetry is not known, but it may be related to bombardment by charged
particles from Uranus's magnetosphere.
The energetic particles tend to sputter water ice, decompose methane trapped in ice as clathrate
hydrate and darken other organics, leaving a dark, carbon-rich residue behind.
Except for water, the only other compound identified on the surface of Ariel by infrared
spectroscopy is carbon dioxide (CO2), which is concentrated mainly on its trailing hemisphere.
Ariel shows the strongest spectroscopic evidence for CO2 of any Uranian satellite, and was
the first Uranian satellite on which this compound was discovered.
The origin of the carbon dioxide is not completely clear (and as we noted there is no atmosphere
to contain it or make sure it's near the surface.
It might be produced locally from carbonates or organic materials under the influence of
the energetic charged particles coming from Uranus's magnetosphere or solar ultraviolet
radiation.
This hypothesis would explain the asymmetry in its distribution, as the trailing hemisphere
is subject to a more intense magnetospheric influence than the leading hemisphere.
Another possible source is the outgassing of primordial CO2 trapped by water ice in
Ariel's interior.
The escape of CO2 from the interior may be related to past geological activity on this
moon.
2.
Origins Of Ariel As with all bodies in the sky, many wondered
how the moons of certain planets formed.
Ariel is thought to have formed from an accretion disc or subnebula; a disc of gas and dust
that either existed around Uranus for some time after its formation or was created by
the giant impact that most likely gave Uranus its large obliquity.
Significant amounts of carbon and nitrogen may have been present in the form of carbon
monoxide (CO) and molecular nitrogen (N2), instead of methane and ammonia.
The moons that formed in such a subnebula would contain less water ice (with CO and
N2 trapped as clathrate) and more rock, explaining the higher density.
The accretion process probably lasted for several thousand years before the moon was
fully formed.
And ever since its forming there have been rocks pelting the surface, including canyons
that may have been around for about 200 million years.
1.
Will We Go To Ariel?
As noted previously, there is a large desire to go and try to make our presence felt throughout
the solar system and there are certain moons out there that might just service our needs.
However, whether Ariel is one of them is up for debate.
Without an atmosphere there are immediate problems involving gas and protection.
The tidally locked rotation doesn't help either.
Add to that, while there has been water detected on the moon it's unclear if it's reachable
in certain areas or will be able to be processed into drinkable amounts.
Not to mention, Uranus is the 7th planet in the solar system and at present it would take
many years to get from Earth to it in a probe, let alone a colony vessel.
It's not out of the question, but it's definitely a place that is on the backburner right now
if you will.
What did you think of this look at Aerial?
Do you see why it's such a special moon to the planet Uranus?
What was your favorite fact you learned?
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