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Unit 46
Ice Worlds, Pluto and Beyond
Copyright (c) The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Beyond Neptune
According to the International Astronomical Union this is
this ends the Major planets.
SO what is beyond Neptune?
Beyond Neptune
Something called: Trans –Neptunian Objects
These objects (known as TNO) are nearly the
same size as Pluto and are beyond Neptune's
It was predicted by
Percival Lowell, based on
perturbation theory, but
later discovered by Clyde
Tombaugh (19061/17/1997) (the first planet
found by an American) in
1930 by a fortunate
– From its discovery in 1930 until 2006, Pluto was
classified as a planet.
– In the late 1970s, following the discovery of
minor planet 2060 Chiron in the outer Solar
System and the recognition of Pluto's relatively
low mass, its status as a major planet began to
be questioned.
• In the late 20th and early 21st centuries, while
searching for more TNO, Mike Brown discovered in
the outer Solar System, an object which he finally
called: Eris in 2005, which is 27% more massive than
• Never again will Pluto be the ninth planet, or the
littlest planet, or the most distant planet.
• Dr. Mike Brown, California Institute of Technology
(Caltech), Pasadena, Calif., associate professor of
planetary astronomy and leader of the research team
On the International Astronomical Union (IAU)
on August 24, 2006, limiting the number to eight
and defines "planet“
a celestial body that, within the Solar System,
• is in orbit (path of one object around a point or another
point) around the Sun;
• has sufficient mass for its self-gravity to overcome rigid
body forces (is an idealization of a solid body of finite
size in which deformation is neglected. In other words,
the distance between any two given points of a rigid body
remains constant in time regardless of external forces
exerted on it.) so that it assumes a hydrostatic
equilibrium (nearly round) shape; and
• has cleared the neighbourhood (of its own orbital zone,
meaning it has become gravitationally dominant, and
there are no other bodies of comparable size other than
its own satellites or those otherwise under its
gravitational influence) around its orbit;
– or
– or within another system,
is in orbit around a star or stellar remnants;
has a mass below the limiting mass for thermonuclear fusion of
deuterium; and
is above the minimum mass/size requirement for planetary
status in the Solar System.
• Pluto, considered a planet for 76 years, was reclassified
as a dwarf planet in 2006.
• On August 24, 2006, The International Astronomical
Union (IAU), the officially defines a "dwarf planet”
Dwarf planet:
• a celestial body that, within the Solar System,
• is in orbit around the Sun;
• has sufficient mass for its self-gravity to
overcome rigid body forces so that it assumes a
hydrostatic equilibrium (nearly round) shape;
• has not cleared the neighbourhood around its
orbit; and
• is not a satellite
• The term "dwarf planet" applies only to objects in
the Solar System. and is quite distinct from "planet"
and "small solar system body".
– After the reclassification, Pluto was added to the
list of minor planets and given the number 134340.
– A number of scientists hold that Pluto should
continue to be classified as a planet, and that other
dwarf planets should be added to the roster of
planets along with Pluto
Trans-Neptunian Objects
• Plutinos are bodies
that orbit the Sun
at more or less the
same distance as
Trans-Neptunian Objects
• Plutinos are
small icy bodies
orbiting the Sun
beyond called
Objects, or
– More than
100 have been
found to date!
– Rotation: 6 days/ 9 hrs/
18 min
– Revolves: 248 years
– distance: 39.529 AU
3 674 490 973 miles
– Gravity: .06
– Tilt 50°
– Incline: 17.2
– MASS: 1.27e22 kg
– SIZE: 1413 miles
– Comp:
• More resembles the
moon Triton
• Pluto's bulk density
is 2,100 kg/m3,
similar to Callisto‘s
• Pluto is a mix of
water ice, rock,
methane and frozen
Pluto is a mix of water ice,
rock, methane and frozen
Pluto orbit is very eccentric
From an
view, it
that Pluto
crosses the
orbit of
But as you can see from a side view, Pluto
DOES NOT cross the orbit of Neptune.
• When Pluto is within Neptune’s orbit,
it has an atmosphere!
– As the planet moves further out in
to the solar system, the atmosphere
snows out onto the surface.
Pluto’s Atmosphere
• Little is known about Pluto's
atmosphere, but it probably consists
primarily of nitrogen with some
carbon monoxide and methane.
• It is extremely tenuous, the surface
pressure being only a few microbars.
Pluto’s Atmosphere
• Pluto's atmosphere may exist as a gas
only when Pluto is near its perihelion;
for the majority of Pluto's long year,
the atmospheric gases are frozen into
Pluto’s Atmosphere
• Near perihelion, it is likely that some
of the atmosphere escapes to space
perhaps even interacting with its
Pluto’s Atmosphere
Formation of Pluto's moons.
• 1: a TNO object nears Pluto;
Pluto’s Moons
Formation of Pluto's moons.
• 2: the KBO impacts Pluto;
Pluto’s Moons
Formation of Pluto's moons.
• 3: a dust ring forms around Pluto;
Pluto’s Moons
Formation of Pluto's moons.
• 4: the debris aggregates to form Charon;
Pluto’s Moons
Pluto’s Moons
Formation of Pluto's moons.
• 5: Pluto and Charon relax into spherical bodies.
Pluto’s Moons
– The innermost moon,
– Was discovered by James Christy on June 22, 1978,
nearly half a century after Pluto.
– Size: 749 miles
– Rotation, Rev, Distance, all the same as Pluto
– Rotation: 6 days/ 9 hrs/
18 min
– Revolves: 248 years
– distance: 39.529 AU
3 674 490 973 miles
– Tilt 50°
– Incline: 17.2
– Almost like a double
planet system
Pluto’s Moons
• Pluto and its largest moon Charon would
fit comfortably within the United States.
Pluto’s Moons
• Charon orbits Pluto at a steep angle to
the ecliptic, and Pluto’s axis is heavily
tipped as well
Pluto’s Moons
Pluto’s Moons
OTHER moons of PLUTO
– Two outer moons were
imaged by the Hubble
Space Telescope Pluto
Companion Search
Team in May 2005.
With the orbits confirmed, the
moons have been given
definitive names: Hydra (Pluto
III, formerly S/2005 P 1)
and Nix (Pluto II, formerly
S/2005 P 2).
– Further Hubble
observations were made
in February and March
– The possibility of rings
where created by
impacts on the smaller
moons scientist think.
Pluto’s Moons
Pluto’s Moons
OTHER moons of PLUTO
– The fourth moon was
announced in July 2011.
– Currently called P4
Pluto’s Moons
OTHER moons of PLUTO
– A fifth moon was
discovered in July 2012.
• Pluto is the only
planet in the solar
system that we
have not visited.
• However that is
soon to change.
• 2015 New Horizon spacecraft will do a
Pluto Flyby
• New Horizon
• ~45000mph (12mi/sec)
• NY to LA in 3½ min
• Pass Jupiter 13 months
• 13 years trip gets there about July2015
• NASA probe, New Horizon, is
planning to arrive at Pluto while the
atmosphere is still unfrozen.
• The probe will record the freezing of
the atmosphere.
Most TNOs, like Pluto, come from an area
that is just beyond Neptune called the
Beyond Neptune
Beyond Neptune
Trans-Neptunian Objects
Haumea Makemake
Let us LOOK at TNO’s
Trans-Neptunian Objects
• More than 130
have been
discovered, one
of them larger
than Pluto!
• Other new
member of "dwarf
planet" are
Eris and Ceres.
Trans-Neptunian Objects
• Here is a picture of
Not the typical asteroid… This
one is ROUND .
Trans-Neptunian Objects
Trans-Neptunian Objects
• Ceres was discovered on
Jan 01, 1801 by Guiseppe
• Ceres has not yet been
seen up close but NASA's
Dawn spacecraft will visit
it in 2015
Trans-Neptunian Objects
• The largest of the asteroids
• The smallest of the dwarf
• Orbit: 277 131 552 mile
from the Sun (average)
• Diameter: 590 miles
Trans-Neptunian Objects
ERIS (2003 UB313)
• Eris was first
found by Mike
Brown and his
team in 2003.
• It was not until
2005 that Eris was
identified as
another possible
planet in our solar
Trans-Neptunian Objects
ERIS (2003 UB313)
• Is the largest
known dwarf
planet in
our solar system.
• It is a little larger
than Pluto. Eris is
about 1491 miles
(2400 Km) wide.
Trans-Neptunian Objects
ERIS (2003 UB313)
• Observations have
led scientists to
believe it has
frozen methane on
its surface.
• Eris appears gray
in color.
Trans-Neptunian Objects
ERIS (2003 UB313)
• Eris was the most
distant member of
our solar system.
• It is 3 times
farther out than
Pluto. One trip
around the Sun
takes 557 Earth
years for Eris.
Trans-Neptunian Objects
ERIS (2003 UB313)
• Eris is the most
distant member of
our solar system
known at this
• It is 3 times
farther out than
Pluto. One trip
around the Sun
takes 557 Earth
years for Eris.
Trans-Neptunian Objects
• Dysnomia
is the only
moon of
Eris that
we now
Very far far away-farther than Pluto is
another Dwarf Planet.
8 billion miles away.
Sedna will be at its
closest approach,
about 72 years from
now and then it will
beginning its 10,500year trip back to the
far reaches of the solar
Trans-Neptunian Objects
The last time Sedna
(the red dot) was this
close to the sun, Earth
was just coming out of
the last ice age.
The next time it comes
back, the world might
again be a completely
different place.
Trans-Neptunian Objects
Trans-Neptunian Objects
Include its size and
reddish color.
After Mars, it is the
second reddest object
in the solar system.
It is estimated Sedna
is approximately 3/4
the size of Pluto
Trans-Neptunian Objects
Coldest known
region of our solar
system, where
temperatures never
rise above -240°
Celsius (-400°F)
Haumea with its
moons, Hiʻiaka
and Namaka
Haumea - A New Birth in
(pronounced how-MAY-ah)
discovered on Dec 28, 2004
by Mike Brown
Trans-Neptunian Objects
Trans-Neptunian Objects
OTHERS (136472)
Makemake (previously known as 2005 FY9
In Search of the
Golden Egg
MAH-keh MAHkeh
- "e" is pronounced
"ay" in Polynesian)
Discovered on March
31, 2005 by Mike
Trans-Neptunian Objects
• Quaoar (pronounced kwah-whar)
• name given to the "creation force“
• Discovered by Mike Brown and Chad Trujillo in a digital
image taken on June 4, 2002
Trans-Neptunian Objects
• Quaoar is about 746 miles in diameter--about onetenth the diameter of Earth, about half the size of
Pluto, and larger than the four primary asteroids
• Quaoar has an
orbital period of
288 years
• Orbiting the sun
in a near perfect
Trans-Neptunian Objects
• Orcus - Oath of the
• Discovered on Feb 19,
2004 by Mike Brown
• Bit smaller than
Pluto, Orcus has a
nearly identical
orbital size, orbital
period (year), and
orbital inclination,
and it has a moon like
Trans-Neptunian Objects
Trans-Neptunian Objects
• However, Orcus' orbital plane's orientation in our
solar system is tilted in the opposite direction from
Pluto's. Orcus is clearly Pluto's compliment.
Trans-Neptunian Objects
• Orcus's 247 year orbit is shaped similarly to Pluto's
(both have perihelia above the ecliptic), but is
differently oriented.
• Orcus is sometimes described as the "anti-Pluto".
SO what is next?
Oort Cloud
Comets also are cosmic debris, probably planetesimals
that originally resided in the vicinity of the orbits of
Uranus and Neptune rather than in the warmer
regions of the asteroid belt.
Thus, the nuclei of comets are icy balls of frozen water,
methane, and ammonia, mixed with small pieces of
rock and dust, rather than the largely volatile-free
stones and irons that typify asteroids.
Oort Cloud
In the most popular theory, icy planetesimals in the
primitive solar nebula that wandered close to
Uranus or Neptune but not close enough to be
captured by them were flung to great distances from
the Sun, some to be lost from the solar system while
others populated what was to become a great cloud
of cometary bodies, perhaps 10 trillion in number.
Such a cloud was first hypothesized by the Dutch
astronomer Jan Hendrik Oort.
Oort Cloud
• In 1950. Dr. Jan Oort noticed that:
– No comet has been observed with an
orbit that indicates that it came from
interstellar space
– There is a strong tendency for aphelia
of long period comet orbits to lie at a
distance of about 50,000 AU
– There is no preferential direction from
which comets come
Oort Cloud