Transcript Classifying Objects in the Solar System

http://www.youtube.com/watch
?v=BYcTN8H7ysw
Good Planets are hard to find
Link to directions:
http://www.astrosociety.org/education/publication
s/tnl/70/pluto.html#10
Link to images:
http://www.astrosociety.org/education/publication
s/tnl/70/solarsystemcards.pdf
SURVEY
Do you think Pluto should be a planet?
YES
Image: Hubble Space Telescope
NO
Read this article
Hubble Observations of Ceres and Pluto
• http://www.astrosociety.org/education/public
ations/tnl/70/pluto.html
There is a handout that goes with this article
titled: Hubble Observations of Ceres and Pluto.
You can find it in the folder titled Classifying
Objects in the Solar System
The Original Definition of a Planet
Planet
is derived from the
Greek word
αστήρ πλανήτης
(Wandering Star)
This was anything that
wandered in the sky
differently that the
fixed stars
How many planets are there?
Geocentric Model (Early Greek)
Total Number of Planets = 7
Heliocentric Model (1550)
Total number of Planets = 6
Due to Reclassification of
Earth, Moon and Sun
This was all that could be seen by the unaided eye.
Then Uranus was discovered (1781)
Total Number of Planets = 7
Total
number
of planets
= 11
Then Astraea was discovered (1845)
Number of planets = 12
At this point
the definition for planet is
still “Wandering Star”.
Moon diameter
compared to the first 10 asteroids
to be discovered
Next came Neptune (1846)
Total number of
planets = 13
Reclassification of 1851
• 1851 – 15 asteroids
• A minor planet is an astronomical object in direct
orbit around the Sun that is neither a dominant
planet nor originally classified as a comet.
• Minor planets can be dwarf planets, asteroids,
trojans, centaurs, Kuiper belt objects, and other
trans-Neptunian objects.[1]
• The first minor planet discovered was Ceres in 1801
(although from the time of its discovery until 1851 it
was considered to be a true planet).
• The orbits of more than 570,000 objects have been
archived at the Minor Planet Center.[2]
How are the planets spaced out?
Use your Pocket Solar System
to roughly describe how
the planets in our solar system
are spaced out?
Does the spacing seem to follow a pattern?
Just worth a note: Titus-Bode Law
Video (4:45 minutes)
http://www.universetoday.com/13573/whypluto-is-no-longer-a-planet/
International Astronomical Union (IAU)
• Planets
• Dwarf Planets
• Small Solar System Bodies
Ceres and Pluto:
Dwarf Planets as a New Way of Thinking
about an Old Solar System
Activity Link:
Definition
A planet is a celestial body that
1. Is in orbit around the
Sun
(or other star if speaking about exoplanets)
2.
Has sufficient mass for its selfgravity to overcome rigid body
forces so that it assumes a
hydrostatic equilibrium shape
(round)
3. Has cleared the
neighborhood
around its orbit.
4. Is NOT a satellite
Examples
Definition
Examples: Ceres, Pluto, Eris
A dwarf planet is a celestial body
that
1. Is in orbit around the Sun
2. Has sufficient mass for its
self-gravity to overcome rigid
body forces so that it
assumes a hydrostatic
equilibrium shape
3. Has NOT cleared the
neighborhood around its
orbit
4. Is NOT a satellite
Click the image to go to Mike Brown’s
Dwarf planet page
Notable Dwarfs
Eris by Hubble
Eris Orbit
Eris Orbit
Eccentricity and Inclination
Eris Discovery
(3 frames over 3 hours)
Notable Dwarfs
Haumea
Sedna
Definition
An asteroid is a celestial body that:
1. Orbits the Sun inside the
orbit of Jupiter
2. DOES NOT have sufficient
mass for its self-gravity to
overcome rigid body forces
so that it assumes a
hydrostatic equilibrium shape
(IT IS NOT ROUND)
3. HAS NOT cleared the
neighborhood around its
orbit
4. IS NOT a satellite
Examples
Comparison of Astroids
Mars and asteroids: size comparisons
Click on the image to visit the
NEAR mission webpage
Ceres
Vesta
Click on the image to visit the
DAWN mission website
TNO’s are
any objects in the Solar
System that orbits the Sun at
a greater average distance
than Neptune.
A Plutoid (or ice dwarf) is
1. trans-Neptunian object
2. dwarf planet: that is, a
body orbiting beyond
Neptune that is large
enough to be rounded in
shape.
Stardust
Click on the Image to link to the Deep
Impact mission page
Definition
• All other objects, except
satellites, orbiting the Sun
Examples
• Most asteroids
• Most Trans-Neptunian
Objects (TNO’s)
• Comets
• Other small bodies
Pluto’s changing landscape
• http://hubblesite.org/news
center/archive/releases/201
0/06/video/a/
Pluto is:
1. Dwarf Planet
2. Kuiper Belt Object
3. Trans-Neptunian Object
4. Plutoid
Link here to PlutoToday.com
http://www.plutotoday.com/
Pluto’s fifth moon!
Click on the
image to view a
short video of
the motion of
the moons.
Click on the image to visit the
NEW HORIZONS mission webpage
Originally You thought a Planet must
have…
Use the Internet to Research
Earth
Ceres
Vesta
1. www.nineplanets.org
2. http://ssd.jpl.nasa.gov/
Pluto
𝑴𝒂𝒔𝒔
𝑫𝒆𝒏𝒔𝒊𝒕𝒚 =
𝑽𝒐𝒍𝒖𝒎𝒆
One Comparison
Earth has a relatively high density
compared to the other three objects
Density
(g/𝑐𝑚3 )
Earth
Ceres
Vesta
Pluto
5.5
2.0
2.4
2.0
The Earth is a planet and the other three are not,
maybe density should be considered when
classifying planets/non planets.
Question:
How does density affect the other characteristics of a planet?
Conclusions
The International Astronomical Union has
chosen one characteristic (the extent to which a
body has cleared its orbital neighborhood of
other bodies) as the distinguishing characteristic
of a planet versus a dwarf planet, there are
many other characteristics to consider.
Conclusions
Many planetary scientists would rather see a
definition that focused more on characteristics
of the body itself rather than where it is or what
is near it.
New Horizons
The more that we learn about our solar
system, the more our classification schemes
are challenged to include new discoveries.
NEAR
IBEX
Neil Degrasse Tyson on Pluto
New York Public Radio (5:10 minutes)
http://www.youtube.com/watch?v=4Rwe54vtv
UA
PBS Movie (The Pluto Files 52:52 minutes)
http://www.pbs.org/wgbh/nova/space/plutofiles.html
Allen Stern’s thoughts on Pluto
(Planetary Scientist)
Nova Podcast (6:30 minutes)
• http://www.pbs.org/wgbh/nova/space/defensepluto.html
Conclusion for Pluto – NOT A PLANET, NOT EVEN
THE LARGEST OF THE DWARF PLANETS, BUT SITS
A CLOSE SECOND!
Mike Brown – CalTech Astrophysicist
http://www.youtube.com/
watch?v=C9pXpXAl8m8&f
eature=related
Facts and Quizzes
Interesting Facts about our Dwarf Planets
http://www.youtube.com/watch?feature=endscreen&v=Ho5F
EyftFss&NR=1
Quiz on Pluto
http://www.space.com/16537-pluto-quiz-dwarf-planetmoons.html
Dwarf Planet Quiz
1. http://www.astronomyquiz.info/dwarf-planets-quiz.html
2. http://www.funtrivia.com/playquiz/quiz3249712533f30.ht
ml
QUIZ IMAGE 1
INFORMATION
This object has not cleared out
its neighborhood orbit.
Image 2
INFORMATION
This object is in an orbit
around the Sun between the
orbits of Mars and Jupiter.
Image 3
INFORMATION
This object is in an orbit
around the Sun between the
orbits of Mars and Jupiter.
Image 4
INFORMATION
This object orbits the Sun past
Neptune’s average distance
from the Sun
Image 5
NFORMATION
This object contains more than
90% of the total mass in its
path around the sun
Image 6
INFORMATION
This object is in an orbit
around the Sun between the
orbits of Mars and Jupiter.
Image 7
INFORMATION
This object would be rounded
but its extreme rotation causes
it to bulge.
Image 8
INFORMATION
This object’s orbit is highly
eccentric.
Image 9
INFORMATION
This object orbits the Sun at an
average distance of .3 AU
Image 10
INFORMATION
This object is the most distant
of 8 objects in its classification.