1. TNO’s

2. Trans-Neptune Objects (TNO’s)
Pluto, Eris, Makemake etc are all icy objects that cross Neptune’s orbit or come close to it They are TNO’s They all have very elipitical orbits At their greatest distance they pass into the Kuiper belt where comets orbit, The largest, (Pluto, Eris, Makemake & Haumea) unlike comets and asteroids have enough mass to be round So they are now called Dwarf Planets There are many TNO’s Possibly hundreds!

3. Eris Eris is the most massive TNO
And with a radius of 1200 km, is the second largest of the TNO’s.
It takes over 500 years to complete its 68 AU average orbit.
Eris has one small moon
Dysnomia

4. Pluto Pluto is the largest TNO but only the second most massive
It’s orbit is tilted 17° from that of the planets and is very elliptical (30-49 AU)
Two more things make it a special TNO:
It is the closest TNO to the Sun and thus was found first
It has a LARGE moon
Charon

5. Charon and Pluto Charon’s radius is about half that of Pluto
They both orbit a point between them
And thus are more like twin planets

6. Makemake At a radius of 950 km Makemake is the third largest TNO.
It is a dwarf planet

7. Haumea Debate raged over the status of Haumea As it is ellipsoidal
But Its elongated shape is the result of it fast spin.
At a period of 4 hours, the fastest known
So now it qualifies as a dwarf planet
It has two small moons,
Hi’iaka and Namaka

8. What should we consider TNO’s
If they have enough mass to be round…
Dwarf Planets