Peculiar Shape

Retrieved from: http://space-facts.com/oort-cloud/

The Oort Cloud is different from any of the other regions of the solar system in a very distinctive way. Unlike any other portion, the Oort Cloud forms a sphere. Unfortunatly, we have never directly observed the Oort Cloud and it is only theoretical at this point. This is because most of the objects that make it up are small dark asteroids and comets. They are so distant from any body of light that they are practically invisible, and combined with how tiny they are it is practically impossible to see them in any calculated way. The way we know that the cloud looks the way it does is because of the numerous long period comets we've observed that come from off of the orbital plane. This is the currently accepted theory as to how those objects are coming from where they appear to be. They were not formed there, however. The currently accepted idea is that they are early solar system objects that were pushed out there by the gravitational force of the giant planets, Jupiter in particular.

Since the Oort Cloud is theoretical and only the best accepted theory of where these strange objects are coming from. There is a chance of course that the Oort Cloud is not actually there. and these things are coming from somewhere else entirely, debris from between solar systems. The shape itself is very strange and notable since it reminds me something of an atom. Forever we thought of electrons as having orbits, but, like the Oort Cloud, through observation it has been modeled as an electron cloud. That the path an electron takes is chaotic and could be anywhere around an atom at any time. Previously we believed that objects in the solar system existed on this orbital plane.

Long-Period Comets

Last post, we talked about the dwarf planet Sedna and some unique traits associated with it and the Oort Cloud. Today, we are going to be looking at the trillions of asteroids floating around out there. You wouldn't think that the tiny rocks way out there would have much effect on the inner solar system. The gravity would seem like it would be to weak to have any significant impact on the space rocks and would barely affect them. It is for this reason, the feebleness of the Sun's gravity on these bodies, that makes them so significant for the inner solar system. If the Sun had a stronger grip on them, they would be in tighter orbits, and we would never see them in our neck of the woods. But, due to gravitational interaction from nearby passing bodies, these rocks can get knocked off their orbit and end up traveling toward the Sun.

http://global.jaxa.jp/article/interview/2013/vol81/img/img_03_l.jpg

These bodies that get knocked off their orbit in the cloud are what we call comets. The Oort Cloud is the place where long-period comets are born. The distance from the sun and the temperature are what end up giving them their telltale signs as a comet. The make up of the comet, from being so far from the sun during its formation, is primarily dust and volatile ices, with a low density rocky/gravelly core. When a comet gets knocked toward the sun, the speed of the comet and the solar wind combined with the speed it is traveling make it hurtle off debris in 2 directions that it travels. One tail is primarily dust, and this one travels along the orbit line, so it will look more curved but a bit shorter, and it is leaving behind it a trail of dust and is generated by the low desnity rock falling off of the comet at it rips through space. The gas tail, or the Ion Tail is produced by the solar winds and will be pointing directly away from the sun, whether the comet is moving toward or away from it. The gas tail is made up of the volatile ices melting off of the comet by the sun's magnetically charged plasma and becoming charged particles.

https://en.wikipedia.org/wiki/Comet_tail#/media/File:Cometorbit.png

http://www.passmyexams.co.uk/GCSE/physics/images/comet.jpg

Next time we will look at the unique shape of the Oort Cloud and why we believe it  is like this even though we cannot see it.

Sedna

First pictures of Sedna, the most distant known planetoid in the solar system.

8 billion miles from our little blue dot is the planet Sedna, making its residence within the Oort Cloud. Sedna is currently the furthest known object in the solar system, aside from the icy comets that also call the Oort Cloud their home. It was discovered in November of 2003 by Michael Brown, Chad Trujillo, and David Rabinowitz when it was close to perihelion at 86 AU, but has a highly elliptical orbit that reaches an estimated 937 AU. It will reach its perihelion in about 70 years, at which time it will start to move away from us. It was lucky for us to catch it when it was so close as it has a 10,000 earth-year year, and we still have plenty of time to study it before it is beyond our reach again.  Designated as a dwarf planet, it is only 1,100 miles in diameter, just slightly less than Pluto but 8-10 times less than Earth, and red.

Its discovery, along with Quaoar and Eris helped to spark a debate within the International Astronomical Union which ended up narrowing  the definition for a classical planet in 2006. They came away with requirements for classical planets being: They must orbit the Sun solely, have a mass that is large enough to be nearly round, and have cleared all debris from its orbit.

The discovery is strong evidence for the existence of the Oort Cloud. Namely its orbital pattern. The pattern is unlike the known solar system, but it syncs up to what predicted objects within the Oort Cloud would be like. Because of the distance from the sun, the gravity it is bound to is fairly weak, and prone to fluctuations from outside influences. Much like comets that come from the Cloud are pushed by closely passing bodies, one may have elongated the orbit of Sedna this way.


Clavin, W. (2004). Planet-Like Body Discovered at Fringes of Our Solar System. Retrieved from http://www.nasa.gov/vision/universe/solarsystem/planet_like_body.html

Howell, E. (2014). Sedna: Possible Dwarf Planet Far From the Sun. Retrieved from http://www.space.com/25695-sedna-dwarf-planet.html

 Jet Propulsion Laboratory: California Institute of Technology. (2015). JPL Small-Body Database Browser. Retrieved from http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=Sedna

OP

The Oort Cloud is a very special place in the Solar System. For the most part, the different parts that make up the Solar System all fall onto or near the orbital plane. This is true for all objects, comets, asteroids, planets, etc. until you get to the Oort Cloud. This shell is located far away from any of the planets, starting at about 2,000 Au and continuing to over 100,000 Au away. It is thought that the material that makes up the cloud is the left over debris from the protoplanetary disk. As such, it was formed much closer to Sol then where it rests now, but due to gravitational influences in the inner solar system, many were flung to where they rest now.  Everything that is within the Oort Cloud is very cold and very old, with a large majority of it dating back to the formation of the solar system. As the objects  within the Oort Cloud are very far from the Sun, it is very hard to see any of the actual objects inside of it and as such have only been able to calculate its realness through mathematical calculations that insist that it must be there.

The Oort Cloud surrounds the Solar System like a shell.

The Oort Cloud is a major object that needs to be studied, and as it is studied there are more bodies within the cloud that are worth mention. As we take a closer look next time we will look at one of the largest objects within the cloud, the planetoid Sedna.

 Space Facts. (2015). Space Facts. Retrieved from http://space-facts.com/oort-cloud/