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!