Space Part 1: Our Solar System: Dwarf Planets, Trans-Neptunian Objects, The Kuiper Belt, The Heliosphere, The Oort Cloud, and all the rest.

Dwarf Planets, Trans-Neptunian Objects, The Kuiper Belt, The Heliosphere, The Oort Cloud, and all the rest.

Before the telescope we knew about the first six planets, the sun, and our moon.  After the advent of the telescope in the 1600's we continued to add more and more the the universe until it literally got so big we cannot see the end of it.  Our own solar system even has increased in size so dramatically that many people really have no idea what is out there.  In this blog post I'll tell you about pretty much anything that isn't one of the eight planets.  The sheer amount of stuff that exists even in our own tiny solar system truly is staggering.

Dwarf Planets

Quick Note, if you don't know the difference between a dwarf planet and a planet I posted a link in my last blog.  There are currently five recognized dwarf planets in our solar system.  In my blog on the asteroid belt, I talked about Ceres, the dwarf planet within the asteroid belt and thus closest to the Sun.

Pluto
The former ninth major planet has had many defenders since it was "demoted" to dwarf planet status back in 2006.  However, with a diameter of of just over 1,500 miles, 600 miles smaller in diameter than our own moon, it's easy to see why Pluto was so easily demoted.  So when you truly consider Pluto's place in our solar system, it really does not deserve to be a planet.

All of this isn't to say that Pluto doesn't have interesting things about it, but saying you don't care what scientists say about Pluto is akin to people who probably forever believed the world was flat despite logical and scientific evidence to the contrary.  To deny advances in science as a result of availability of information is foolhardy and I encourage all of you to educate yourselves and come to an informed conclusion.  The above image demonstrates pretty much everything there is to say about Pluto and I love how a picture as simple as this can convey so much information!  First, Pluto is about 4.6 billion miles from the Sun at its furthest and 2.6 at its closest.

Interestingly, because Pluto's orbit is so elliptical, sometimes it gets closer to the Sun than Neptune and even develops a small atmosphere.  As you can see from the image directly above, Pluto's orbit is very elliptical and different from the eight major planets (more on that later).  The amazing distances associated with Pluto mean that no spaceship has ever been sent with the express mission of visiting Pluto.  The image I showed above with just 6 small dots of light in the distance demonstrates how far away it really is.  It's so far away that even telescopes like Hubble can't take detailed images of it.

This is the most detailed image of Pluto that the Hubble space telescope can take.

However! The New Horizons Spacecraft will arrive in Pluto's orbit in 2015 and will give us the first ever detailed images of Pluto and its moons (I absolutely cannot wait).  With the arrival of New Horizons we will be able to know more information about Pluto overnight than has ever been compiled since it was first discovered; I think that's pretty cool.  Again, the thing that makes Pluto so difficult to study is that it's simply so far away from us.  That distance means that Pluto's environment reaches near absolute zero on its surface (-430 degrees Fahrenheit, just 29 degrees away from the coldest possible temperature), making it near impossible to land any type of craft on its surface.  In addition to that, as again demonstrated by the image I showed earlier, scientists recently discovered that Pluto, despite its tiny size, has about 5 moons around it and possibly more.  This makes it very difficult to program a satellite so that it doesn't simply get demolished upon arrival; they had to change where New Horizons was going to orbit Pluto based on the locations of the newly discovered moons.  Pluto is in some ways a sad story and in some ways brilliant because although Pluto got demoted from big boy planet status, its demotion paved the way for new discoveries in the outer reaches of our solar system, including renewed interest in Pluto itself!

Eris

Scientists believe Eris could be 25% larger than Pluto but they just don't know exactly how large it is.  The small dot to the left of Eris is its moon Dysnomia

Here it is, the dwarf planet that "killed" Pluto.  When Eris was first discovered in 2005, its discoverer thought he had discovered the tenth planet, and in the terms of the day he really had.  He also had no idea that he had just sparked one of the most intriguing astronomical debates in history: what really makes something a planet?  Eris is cool not because of what we know about it, because honestly we know very little, but because of what Eris made us realize: there could be hundreds if not thousands of dwarf planets out there, specifically in the Kuiper Belt (more on this later).  We know so little about Eris that scientists don't know whether or not it is larger than Pluto, they just list it as having a diameter of about 1,500 miles.  This again comes down to the sheer distances in between us and Eris.  Eris takes about 550 years to go around the Sun and has an orbit even more elliptical than Pluto and coincidentally Eris was discovered very close to the time that it is furthest away from the Sun.

In our context, Pluto has an extremely elliptical orbit.  But then, you look at Eris and go wow!

 Right now, Eris is twice as far away as Pluto is from the Sun, nearly 9 billion miles away.  Hopefully some day, we will be able to learn more about all of the bodies within our solar system.

Make Make and Haumea

The final two currently confirmed dwarf planets in the Solar System are MakeMake and Haumea, both of which lie inside the Kuiper belt (more on this later).  Again, scientists think they are both a bit smaller than Pluto, but telling the actual size is a bit difficult due to their distance from us.  MakeMake's special feature is that it is the only Dwarf Planet discovered that has no moon.  Pretty much all of the dwarf planets that they find at these distances are made of the same icy materials (water ice, ammonia ice, methane ice, and other random stuff thrown in).

MakeMake, the freak with no moon.

 Haumea's unique feature is that it is one of the fastest spinning objects we have found in the solar system and thus one of the most oddly shaped.  Most objects when they reach the mass required to gravitationally collapse into a sphere, remain as a sphere.  Haumea is spinning so fast, it revolves once every 4 hours, that it the sheer centrifugal force overrides the force of gravity and makes Haumea look quite elongated.

NASA created this image of Haumea because it has never actually been imaged in this much detail.

This elongation is theorized to be a result of a collision and scientists are in fact able to trace bodies back to collisional groups (basically bodies that originated in the same place or were part of the same impact).

This is the most detailed image of Haumea that we have.  Without a doubt, more dwarf planets will be discovered, confirmed, and denied in the future.


The Kuiper Belt

The traditional Solar System that we think of extends outward from the Sun to the orbit or Neptune, or about 30 AU's (astronomical units(1 distance between the Earth and the Sun or about 93 million miles)) away.  In reality, the Solar System extends outwards possibly as far as 100,000 AU's or even further!  The Sun is so wildly powerful that its influence nearly extends nearly half way to the nearest star about 4 light years away.  However, before we go that far out, it is important to consider an area of our Solar System that lies from just beyond the orbit of Neptune at 30 AU's to about 55 AU's from the Sun.  This area of the Solar System is known as the Kuiper Belt and it is one of the most dynamic areas of our Solar System.

I've made the above image very large so that you can get an idea of the sheer scale of the Kuiper Belt, a nearly 2.5 billion mile wide area of space filled with an estimated 2 trillion objects, 100,000 of which scientists estimate to have a diameter greater than 100km (60 miles).  It is theorized and extremely likely that the Kuiper belt is mostly all the leftover stuff from the creation of the Solar System that didn't coalesce into planets.  However, because there is just so much stuff in such a gigantic area, some of the objects have become quite large and in fact, we know of many very large objects that originated or are still within the Kuiper Belt.  For example, scientists believe that Pluto originated within the Kuiper belt because it is made of the same materials and has a wildly elliptical orbit, implying it was captured by the Sun as opposed to formed around it.  Another example would be Neptune's moon Triton is the only moon in the solar system with a retrograde orbit, meaning it orbits Neptune the opposite way that the planet itself rotates.  This observation also implies that Triton was likely captured by Neptune as opposed to forming with it.  These large icy bodies: Pluto, Eris, Triton, MakeMake, Hauemea, and many others apparently all originated in the Kuiper Belt.  This new era of discovery began after the discovery of Eris in 2005 and will continue to expand as telescopes keep getting better.

All bodies here are shown with their respective moons.

These large objects in the Kuiper Belt that have been classified as dwarf planets are far outnumbered by  objects that are not small enough to even be classified as dwarf planets.  The images above and below show some of the larger objects that have been found within the Kuiper belt.  The image above shows the largest of these objects and their moons while the image below shows their respective orbits.  All of these objects orbit within the Kuiper Belt with Pluto getting the closest to the Sun out of any of them, the main reason why it was thought to be the ninth planet for so long.

Here are the orbits of the largest Trans Neptunian objects that we know about.

The one body here that does not seem to fit the bill is Sedna.  Sedna's orbit is completely insane compared to any other object in the solar system.

Sedna's orbit is a perfect segway into the final blog on our Solar system where I will be talking about the Heliosphere, the Oort Cloud, and why Sedna's orbit is so crazy.  Stay tuned!

Space Part 1: Our Solar System: Neptune

So here we are, the end of the major planets of our solar system.  I know some of you are still thinking: "Yah whatever, Pluto will always be a planet to me.  To you I say go read some scientific papers by the people who work at NASA.  Some of them are surprisingly interesting and to be honest, the explanations they give make complete and total sense.  For those of you interested in reading a simpler explanation from an actual authority, here's NASA's explanation: PLUTO ISN'T A REAL PLANET GET OVER IT.

Neptune

One of my favorite things about Neptune is the way it was discovered.  Scientists had recently discovered Uranus and after mapping its orbit, realized that something else was having an affect on Uranus' orbit.  It was hypothesized that there must be another large planet that had yet to be discovered and sure enough, less than 20 years after the irregular orbit had been observed, Neptune was discovered in 1846.  Normally, I don't really care all that much about how the planets in our solar system were discovered.  Not that the stories aren't cool, but at the initial point of discovery we always know very little about said planet or body and it isn't until much later that we start learning really cool things about them.  I just enjoy that Neptune was the first planet discovered through mathematical means rather than through empirical observations by humans on the ground.

The picture above shows as size comparison between the Earth and Neptune, Earth has a diameter of about 7,918 miles while Neptune has a diameter of 30,599 miles (just over 3.8 times larger than the Earth).  Now, most people when they think of Neptune, they think a cold gas planet at the edge of our solar system.  While this view is partially correct, as Neptune does in fact contain a massive amount of hydrogen and helium, we now know that what makes Uranus and Neptune different from Jupiter and Saturn is the presence of massive amounts of water ice, ammonia ice, and methane ice.

As you can see from the image above, Neptune has several main layers, very similar in composition to Uranus.  A deep outer layer of hydrogen, helium, and methane (which gives Neptune its blue color) and than an inner layer of "ice."  Now, ice is a term used here in very loose terms because really, while there is in fact some legit water ice, the sheer amount of mass and resulting gravitational forces cause these compounds to behave so strangely that they are often referred to as an icy-ammonia-methane-ocean even though the layer is actually a very dense and very hot liquid (type thing, they really don't know what the heck it really is).  Now, we know that Neptune and Uranus are composed of pretty much the same things, but one thing we do know is that Neptune is for some reason a lot more active on the surface than Uranus is.

Storms on Neptune experience the fastest winds and some of the coldest temperatures in the solar system, reaching speeds of 1,300 miles per hour and temperatures as low as -360 degrees Fahrenheit; seriously cold.  We know why the planet should be cold as it is over 2.78 billion miles from the Sun, but why should a planet that receives very little energy from the sun have storms with winds that are consistently over 1300 miles per hour?  Scientists believe that a combination of internal heat and sheer lack of friction are the causes.  With nothing majorly solid getting in the way, the winds have been getting faster and faster over millennia and who knows if they will ever slow down.  Neptune even had it's own super storm: "The Great Dark Spot" much like Jupiter's great red spot, was a storm that had been active since scientists first discovered Neptune and who knows how long before then.  Until in 1994, scientists could no longer see the storm on the surface; it had either finally stopped or has become obscured.  In addition, like all of the large planets, Neptune has a small ring system probably leftovers from the formation of the planet billions of years ago.

Picture of Neptune's rungs as imaged by Voyager.  Neptune itself has been blacked out.

Neptune also has 13 known moons, although there are probably a lot more we have yet to discover, with the largest being Triton (Triton contains 99% of the mass of all of Neptune's moons).

 Triton is the seventh largest moon in the solar system with a diameter of 1,700 miles and is the only large moon with a retrograde orbit (it orbits the opposite way that Neptune rotates) and because of this, scientists believe that Triton was formed elsewhere and later gravitationally captured by Neptune.

Our moon, Triton, and the Earth

  This is further proved by the fact that this retrograde orbit is causing Triton to slow down and will eventually cause Triton to either fall into Neptune or be ripped apart by the sheer force of gravity.  Triton is also famous for having some of the coldest temperatures in the solar system, so cold in fact, that 55% of the surface is covered in nitrogen ice (nearly -400 degrees Fahrenheit).  The other 12 moons are all shaped funny and have no seriously interesting facts about them so I'm not going to bother mentioning them.

And now we have arrived at the end of the major planets.  The next blog will cover pretty much all of the rest of the Solar system: the Kuiper belt, dwarf planets, and the edge of the solar system; stay tuned.