1. Goal: To understand what the Kuiper Belt is, and why it is important
Objectives:
To understand how we find Trans-Neptunian Objects
To explore Pluto and its moons
To learn about Plutinos
To learn about Classical region
To learn about Scattered Disk Objects

2. Difficulties in understanding the Kuiper Belt
< 1000 Trans Neptunian Objects (TNOs) found.
Mass distribution unknown.
Spatial distribution unknown.
square degrees needed just to find a single 500 km TNO.

3. TNO movement – at opposition
148”
Movement rate(in “/hour) =
R(in AU) + R1/2(in AU)

5. Location – expect ecliptic plane
Outside orbit of Neptune, but pretty much everywhere above and below the plane.

6. Do TNOs have their own plane?
If TNOs fall onto a plane their plane seems to differ from the Ecliptic plane (the plane the planets are on) by 2-6 degrees!
Below are objects from a survey I did.

7. TNOs in general Mostly icy.
Source of short period comets (comets with periods of less than 300 years).
How? If an object is thrown from the Kuiper Belt, it first ends up in the region of the gas giants. These objects are known as Centaurs.
Then, interactions with Jupiter can send it closer to the sun where it becomes a comet.
There are BILLIONs of them we have not found!

8. Why are TNOs important?
TNOs are made of materials that have not changed since the formation of the solar system.
This means by studying them we can see what our solar system was like 4.5 billion years ago.
Why no planets? Well, as you went further out there was less stuff, and it took longer for the stuff that was there to collide, so smaller objects were the result.
Current total mass is about 10% of the mass of the earth.

9. Pluto Pluto is one of the known largest TNOs (but not the largest!).
Pluto’s diameter is about 2300 km.
Mass is 0.22% of Earth’s.

10. Pluto Prediction! The surface of Pluto is VERY reflective.
Some of this is due to the atmosphere on Pluto (3 microbars, mostly Nitrogen + some Methane).
What happens is that when Pluto is closest to the sun, nitrogen sublimes from the surface, and then freezes onto the surface when Pluto gets further away (did I mention it gets VERY cold on Pluto!).
However…

11. However…
We are seeing similar surface conditions on other large outer solar system objects which have moons.
So, there might be some small amount of tidal heating from its large moon Charon (Charon is half the diameter of Pluto).
This could create just enough heating to generate Nitrogen volcanoes! (does not take much to unfreeze Nitrogen).
So, you heard it here first, I predict that when the probe we have just sent to Pluto gets there it will find VOLCANOES!
Probe New Horizons will get there in 2015, and will pass by Jupiter Feb. 28, 2007.

12. Pluto
How many known moons does Pluto have?

13. 4 moons and counting

14. Pluto + Charon BOTH tidally locked to each other!
This means that each rotate once every 6.39 days which is the same as the orbit (orbital distance, km).
Charon’s creation is a mystery, but might have been created long ago by a collision with Pluto.

15. Bizarre facts
Pluto is tilted by 120 degrees. Yes, that is more that tipped over.
Like Venus, Pluto rotates backwards.

16. However, Pluto is just one of many objects called Plutinos
Plutinos are objects which all have a 3:2 orbital resonance with Neptune.
There are millions of them.
All have highly eccentric orbits and have average distances of about 39.8 AU from the sun.
Why is this stable?

17. Recap: Pluto isn’t a major planet because…
It is too small (smaller than our moon).
Isn’t even the largest known TNO.
Has an orbital resonance (3:2) with Neptune.
Shares an orbit with millions to hundreds of millions of other Plutinos.
Pluto is considered a dwarf planet and is considered a TNO.

18. The 3 main parts of the Kuiper Belt diagram from Wikipedia.com

19. Classical Region Ranges from 42-47 AUs
Classical Region Ranges from AUs. Quaoar and Varuna are the most famous objects from this region.

20. Scattered Disk Objects which cross Neptune’s orbit – probably had a close encounter sometime in the past. May become comets in billions of years.

21. Eris
Largest known TNO km in diameter.
Moon is
Dysnomia.

22. Sedna Sedna throws a monkey wrench in the Kuiper Belt.
Sedna’s orbit is VERY eccentric!
It goes from 76 AUs to 975 AUs!
There is no way to explain this odd orbit.

23. Wikipedia Sedna Perihelion will be in 2075.
Orbital period is years.
So, we are lucky to find it.
Are there more?

24. largest

26. Conclusion The Kuiper Belt is still a very unexplored place.
We still have millions of objects to find, and then take a closer look at.
This could be an exciting place of the solar system to research for a few decades to come.
However, the solar system does not end here!