1. Small Bodies of the Solar System
Dwarf Planets, Asteroids, Meteoroids/ Meteors/Meteorites and Comets

2. I. What makes a Planet a Planet??
According to the International Astronomical Union (IAU), “A planet:
is a body that orbits the Sun,
is massive enough for its own mass (and gravity) to make it round, and
has "cleared its neighborhood" of smaller objects around its orbit. ”

3. I. What makes a Planet a Planet??
Planetary vs. Dwarf Planet Characteristics
What makes a planet, according to the definitions adopted by the IAU -
Characteristic
Planet
Dwarf Planet
Is in orbit around the Sun
Yes
Is in orbit around a planet (satellite) No
Has sufficient mass (and gravity) to assume a nearly round shape
Has cleared the neighborhood around its orbit

4. I. What does a Planet have that a Dwarf Planet does not have??
Planetary vs. Dwarf Planet Characteristics
What makes a planet, according to the definitions adopted by the IAU -
Characteristic
Planet
Dwarf Planet
Is in orbit around the Sun
Yes
Is in orbit around a planet (satellite) No
Has sufficient mass (and gravity) to assume a nearly round shape
Has cleared the neighborhood around its orbit

6. II. Earth’s Moon is awfully big: why isn’t it a Dwarf Planet?
Dwarf Planet vs. Moon Characteristics
What makes a planet, according to the definitions adopted by the IAU -
Characteristic
Earth’s Moon
Dwarf Planet
Is in orbit around the Sun No
Yes
Is in orbit around a planet (satellite)
Has sufficient mass (and gravity) to assume a nearly round shape
Has cleared the neighborhood around its orbit
N/A

7. 3A. What does a Dwarf Planet have that an Asteroid does not have??
Dwarf Planet vs. Asteroid Characteristics
What makes a planet, according to the definitions adopted by the IAU -
Characteristic
Asteroid
Dwarf Planet
Is in orbit around the Sun
Yes
Is in orbit around a planet (satellite) No
Has sufficient mass (and gravity) to assume a nearly round shape
Has cleared the neighborhood around its orbit

8. The 3rd Dwarf Planet NOT a Dwarf Planet
3A. Ceres – the largest object in the Asteroid Belt:
Orbits the sun
has enough mass to assume a round shape
Will be visited by Dawn mission Feb – July, 2015
The 3rd Dwarf Planet
NOT a Dwarf Planet
3B. Vesta – a smaller Asteroid:
Also orbits the sun
Does not have enough mass to assume a round shape
Was visited by Dawn mission in

10. Asteroid Vesta
As viewed by the Dawn spacecraft

11. II. The First 3 Dwarf Planets
Luna – Earth’s Moon
Not a dwarf planet – it orbits the Earth!
IIA) Eris and its moon Dysnomia
(found in the
Scattered Disk)
II. The First 3 Dwarf Planets
IIB) Pluto and its moon Charon
(found in the
Kuiper Belt)

12. IIA) Eris – is the largest object in the Scattered Disk region:
Greek goddess of Strife and Discord
Tossed from the Kuiper Belt into the Scattered Disk by gravitational interaction with Neptune.
Average distance from the Sun is 67.7 AU
Its orbit is highly eccentric – varies from 38.3 AU to 97.7 AU.

13. IIA) Eris – is the largest object in the Scattered Disk region:
Takes about 560 years to orbit the sun
Discovered in 2003, then classified a Dwarf Planet along with Pluto and Ceres in 2006.
Temperature ranges from -217 oC to -243 oC – Brrr!!
Has 1 moon – Dysnomia (named for the goddess of lawlessness)

14. Eris and Dysnomia
Artist’s View
Photo from HST

15. The Scattered Disk Home to Asteroids, Some Comets
and Dwarf Planet Eris

16. Scattered Disk and Eris’ Orbit

17. 2C) Pluto – is the largest object in the Kuiper Belt:
Discovered in 1930 and named the 9th planet
Reclassified as a Dwarf Planet in 2006.
Name for the Roman god of
the Underworld
Temperature hovers around
from -225 oC – Still Brrr!!
Has 1 large moon – Charon

18. 2C) Pluto – is the largest object in the Kuiper Belt:
Pluto may have been a moon of
Neptune which collided with
Triton, which was not a moon
of Neptune at first but is now!!
(and it orbits backwards)!!

19. 2C) Pluto – is the largest object in the
Kuiper Belt:
Average distance from Sun is AU
Orbit highly eccentric – AU  AU.
Takes about 248 years to orbit the sun
Takes 6.4 days to rotate on its axis (and it does so backwards – retrograde )

20. 2C) Pluto – is the largest object in the
Kuiper Belt:
Rocky core surrounded by a mantle of water ice, with methane and nitrogen ice frosting its surface.
Pinkish color of surface may be due to complex organic compounds
Has a temporary atmosphere when it is closer to the sun, thawing the methane and nitrogen frost.
Has 225 mph winds, but thin air makes them feel like 1 mph breeze on Earth.

21. The Kuiper Belt Where Some Meteorites and a Few Comets Originate and Where Dwarf Planet Pluto is Found

22. Kuiper Belt and Pluto’s Orbit
Pluto will be visited by the New Horizons spacecraft in July, 2015

23. Water Ice Mantle Rocky Core
Methane/Nitrogen “Frost” coats the surface.
Water Ice Mantle
Rocky Core
Click on star for Video – “Why Pluto is Not a Planet”

24. IID) Trans-Neptunian Objects (TNOs) – Eris, Pluto and other objects found out past the orbit of Neptune in the Kuiper Belt and Scattered Disk regions: Haumea, Makemake and other possible candidates for “dwarf planethood”

25. IIE. Ceres - is the largest object in the Asteroid Belt. Ceres:
Originally called a planet when discovered in 1801.
Reclassified as the largest Asteroid in 1802.
Reclassified again as a dwarf planet in 2006, but
(It’s OK to still call it the largest Asteroid.)
Contains 1/3 of the
total mass of the
Asteroid Belt!
Is about 2.77 AU from the sun
Is about ¼ the diameter of Earth’s
Moon - about 950 km in diameter
Moon
Ceres
The 3rd Dwarf Planet
Earth

26. The 3rd Dwarf Planet IIE. Ceres - is the largest object in the
Asteroid Belt. Ceres:
Thought to have a rocky core
overlain by an icy mantle and an
outer surface of water ice mixed
with dust (clay and CO3)
May have liquid water under the
surface
The 3rd Dwarf Planet

27. The 3rd Dwarf Planet IIE. Ceres - is the largest object in the
Asteroid Belt. Ceres:
May have a thin atmosphere of
sublimated water (ice  vapor)
Much rounder than most
Asteroids – due to its mass
Will be visited by Dawn mission
from February to July, 2015
The 3rd Dwarf Planet

28. 3A. What does a Dwarf Planet have that an Asteroid does not have??
Planetary Characteristics
What makes a planet, according to the definitions adopted by the IAU -
Characteristic
Dwarf Planet
Asteroid
Is in orbit around the Sun
Yes
Has sufficient mass to assume a nearly round shape No
Is not a satellite (moon)
Has cleared the neighborhood around its orbit
Has not cleared the neighborhood around its orbit

29. III. The Asteroid Belt Where Meteorites Come From and
Where Dwarf Planet Ceres is Located

30. III. The Asteroid Belt IIIA. The asteroid belt contains:
1 dwarf planet (Ceres – 950 km across)
200 large asteroids ( km across)
750,000 medium-sized asteroids (> 1 km across)
Millions of tiny asteroids and meteoroids.
IIIB. Asteroids are also found:
in Neptune’s orbit (called Trojan Asteroids) and
a trio of Asteroid groups patrolling the inner solar system known as the Near-Earth Asteroids (including the Apollo Asteroids).

31. Other Asteroids – “Space Potatoes”
Lutetia – a smaller Asteroid:
Also orbits the sun
Does not have enough mass to assume a round shape

32. 3C. Asteroids vs. Meteoroids
IIIC. The official definition of a meteoroid:
“A meteoroid is a solid object moving in interplanetary
space, of a size considerably smaller than an asteroid
and considerably larger than an atom.”
The distinction between meteoroid and asteroid:
Traditionally, anything smaller than 10 meters across was called a meteoroid. (A meteoroid would fit inside our classroom.)
Anything greater than 10 meters across is called an asteroid (until you get to Dwarf Planet size!!).

33. 4. Meteoroids vs. Meteors vs. Meteorites
IV. Asteroids and meteoroids both refer to solar system objects that orbit the Sun but are not large enough to be deemed planets.
Meteoroid: any Sun-orbiting object smaller than 10 meters across. (still out in space)
Meteor: visible path of a meteoroid whose surface is vaporizing as it enters Earth's atmosphere (sometimes called a shooting star).
Meteorite: If a meteoroid survives the fall through Earth’s atmosphere as a meteor and lands on Earth’s surface, it becomes a meteorite.
Up to 10,000 tons of meteoritic material fall to Earth every day (mostly tiny pieces - micrometeorites.)

34. Meteoroid
Meteor
Meteorite

35. 4. Meteoroid to Meteor to Meteorite

37. Meteor Showers
Meteor

38. Large Meteoroid
Fragmenting In
Atmosphere

39. Meteors

40. February, 2013 – Chelyabinsk Meteorite punches hole in ice in nearby lake.
October, 2013 – 1500 lb chunk of meteorite is retrieved from lake!

41. IVE. Three main groups of meteorites
Iron meteorites are almost completely metal
Stony-iron meteorites have nearly equal amounts of metal and silicate crystals
Stony meteorites are dominated by silicate minerals.
There are some rare stony meteorites called Martian meteorites because they were blasted off of the surface of Mars and landed here on Earth!

42. Meteorites Stony Iron Iron Stony Iron Iron
A sawed iron meteorite showing criss-crossing Widmanstatten texture.
Stony Iron
Iron

43. To view raw footage of Chelyabinsk meteor and meteorite impact, click:
To view NDGT interview re: Chelyabinsk meteor and meteorite impact, click:
To view video of huge 1300 lb meteorite retrieved from lake near Chelyabinsk, click:

44. The Oört Cloud Where Comets Come From

45. Comet ison
Approaching the Sun
october - november, 2013

46. Comet ison
october - november, 2013

47. Comet ison
october - november, 2013

48. Current indications are…no.
Will ISON survive?...
Scenario 1:
Fizzle: ISON evaporates under intense tidal forces and solar radiation
Scenario 2:
Break-Up: ISON breaks up into smaller chunks (could happen at any time)
Scenario 3:
Sizzle: ISON survives and emerges so bright that it may be visible on Earth even if daylight!
Current indications are…no.
It appears to have broken up into 1000s of pieces as it “grazed” the sun
(Scenario 2).

49. To view animation of Life Cycle of a typical comet:
To view animation of approach and destruction of Comet Ison, October - December, 2013: