Transcript Solar System 09 - MrFuglestad

A Look At Our Solar
System And Beyond
Our Solar System
Our Solar System
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the Sun
the eight planets
more than 130 satellites of the planets
a large number of small bodies (the comets
and asteroids)
• and the interplanetary medium
• (There are probably also many more
planetary satellites that have not yet been
discovered)
The Sun
• Our Sun is a normal mainsequence G2 star, one of
more than 100 billion stars
in our galaxy.
• Diameter: 1,390,000 km
• Mass: 1.989 x 1030 kg
• Temperature: 5800 K
(surface) 15,600,000 K
(core)
The Sun
• The Sun is by far the
largest object in the
solar system. It
contains more than
99.8% of the total
mass of the Solar
System
– (Jupiter contains
most of the rest)
The Sun
• It is often said that the Sun is an "ordinary" star.
That's true in the sense that there are many
others similar to it. But there are many more
smaller stars than larger ones; the Sun is in the
top 10% by mass.
• The median size of stars in our galaxy is
probably less than half the mass of the Sun.
The Sun
• The Sun is, at present, about 70%
hydrogen and 28% helium by mass
everything else ("metals") amounts to less
than 2%.
• This changes slowly over time as the Sun
converts hydrogen to helium in its core.
The Sun
• The Sun's energy output (386 billion billion
megawatts) is produced by nuclear fusion
reactions.
• Each second about 700,000,000 tons of
hydrogen are converted to about
695,000,000 tons of helium and 5,000,000
tons of energy in the form of gamma rays
The Inner Planets
Mercury
Mercury
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Orbit: 57,910,000 km (0.38 AU) from Sun
Diameter: 4,880 km
Mass: 3.30 x 1023 kg
Temperature variations on Mercury are the
most extreme in the solar system ranging
from 90 K to 700 K
Mercury
• Mercury has a small
magnetic field whose
strength is about 1%
of Earth's
• Mercury has no
known satellites
Mercury
• Mercury has been visited by only one
spacecraft, Mariner 10.
• It flew by three times in 1974 and 1975.
• Only 45% of the surface was mapped
(and, unfortunately, it is too close to the
Sun to be safely imaged by HST).
• A new discovery-class mission to
Mercury, MESSENGER was launched
by NASA in 2004 and will orbit Mercury
starting in 2011 after several flybys
Venus
Venus
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Orbit: 108,200,000 km (0.72 AU) from Sun
Diameter: 12,103.6 km
Mass: 4.869 x 1024 kg
Venus is sometimes regarded as Earth's sister
planet. In some ways they are very similar:
– Venus is only slightly smaller than Earth (95% of
Earth's diameter, 80% of Earth's mass).
– Both have few craters indicating relatively young
surfaces.
– Their densities and chemical compositions are
similar.
Venus
• Because of these similarities, it was
thought that below its dense clouds
Venus might be very Earthlike and
might even have life.
• But, unfortunately, more detailed
study of Venus reveals that it may be
the least hospitable place for life in the
solar system.
Venus
• The pressure of Venus'
atmosphere at the surface is 90
atmospheres.
• That’s about the pressure at a
depth of 1 km of below ocean!!
• It is composed mostly of carbon
dioxide.
• There are several layers of
clouds many kilometers thick
composed of sulfuric acid
Venus
• The dense atmosphere produces
a greenhouse effect that raises
Venus' surface temperature by
about 400 degrees to over 740 K
(hot enough to melt lead)
• Venus' surface is actually hotter
than Mercury's despite being
nearly twice as far from the Sun.
Image from Pioneer Venus
Akna Mountains and Crater Wanda
7 Pancake Volcanoes
Photos from Soviet Venera 13
Spacecraft
Earth
Earth
• Orbit: 149,600,000 km (1.00 AU) from Sun
• Diameter: 12,756.3 km
• Mass: 5.972 x 1024 kg
• It was not until the time of Copernicus (the
sixteenth century) that it was understood
that the Earth is just another planet!!
Earth
• The core is probably composed mostly of
iron (or nickel/iron) though it is possible that
some lighter elements may be present, too.
• Temperatures at the center of the core may
be as high as 7500 K, hotter than the surface
of the Sun.
• We know most of this only from seismic
techniques.
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Crust divided into several plates
Plates float on top of mantle
Surface recreated every 500,000,000 years
Oldest rocks 4 billion years old
Rocks older than 3 billion are rare
Oldest fossils are 3.9 billion years old (algae)
Earth
• 71 Percent of the
Earth's surface is
covered with water
• The Earth's
atmosphere is 77%
nitrogen, 21%
oxygen, with traces of
argon, carbon dioxide
and water
Strait of Gibraltar from Shuttle
Earth
• Earth has a modest
magnetic field produced
by electric currents in the
outer core.
• The interaction of the
solar wind, the Earth's
magnetic field and the
Earth's upper
atmosphere causes the
auroras!! (Northern
Lights)
Moon
•First landed on moon in
July 1969
•Last went to moon in 1972
•Less than 10 people have
ever walked on the moon
Moon
• Orbit: 384,400 km
from Earth
• Diameter: 3476 km
• Mass: 7.35 x 1022 kg
Moon - Tides
• The gravitational forces
between the Earth and
the Moon cause some
interesting effects.
• The most obvious is the
tides. The Moon's
gravitational attraction is
stronger on the side of
the Earth nearest to the
Moon and weaker on the
opposite side.
Moon - Tides
• Since the Earth, and
particularly the oceans, is
not perfectly rigid it is
stretched out along the
line toward the Moon.
• From our perspective on
the Earth's surface we
see two small bulges, one
in the direction of the
Moon and one directly
opposite.
Mars
Mars
• Orbit: 227,940,000 km
(1.52 AU) from Sun
• Diameter: 6,794 km
• Mass: 6.4219 x 1023 kg
• Temperature: 140 K (-207
F) at the pole in winter,
300 K (80 F) at equator in
summer.
• Has two moons - Phobos
& Deimos
Mars
• The first spacecraft to visit Mars was Mariner 4
in 1965.
• Several others followed including Mars 2, the
first spacecraft to land on Mars and the two
Viking landers in 1976.
• Ending a long 20 year hiatus, Mars Pathfinder
landed successfully on Mars on 1997 July 4.
• In 2004 the Mars Expedition Rovers "Spirit" and
"Opportunity" landed on Mars sending back
geologic data and many pictures; they are still
operating after more than a year on Mars.
Mars
• Three Mars orbiters (Mars Global Surveyor,
Mars Odyssey, and Mars Express) are also
currently in operation.
• Olympus Mons-78,000 ft high, about
the area of Arizona
• Valles Marineris-System of canyons,
4000 km long, 2-7 km
deep
Candor Chasma in Valles Marineris on Mars
The Outer Planets
• Several hundred thousand known asteroids
• 26 larger than 200 km wide
• Total mass of all asteroids less than mass of
moon
• Largest: 1 Ceres--988 km in diameter,
accounts for 25% of all asteroid mass in solar
system.
• Asteroid belt exists between Mars and Jupiter,
about 2-4 AU from sun
Jupiter
• Orbit: 778,330,000 km
(5.20 AU) from Sun
• Diameter: 142,984 km
(equatorial)
• Mass: 1.900 x 1027 kg
• Jupiter is more than
twice as massive as all
the other planets
combined (the mass of
Jupiter is 318 times that
of Earth)
• Jupiter was first visited by Pioneer 10 in 1973
and later by Pioneer 11, Voyager 1, Voyager 2
and Ulysses.
• The spacecraft Galileo orbited Jupiter for eight
years.
• It is still regularly observed by the Hubble Space
Telescope.
• The gas planets do not have solid surfaces, their
gaseous material simply gets denser with depth
• Our knowledge of the interior of Jupiter (and the
other gas planets) is highly indirect and likely to
remain so for some time. (The data from Galileo's
atmospheric probe goes down only about 150 km
below the cloud tops.)
• Jupiter probably has a core of rocky material
amounting to something like 10 to 15 Earthmasses.
• Jupiter and the other gas planets have high
velocity winds which are confined in wide bands
of latitude.
• The winds blow in opposite directions in adjacent
bands.
• The colors correlate with the cloud's altitude:
blue lowest, followed by browns and whites,
with reds highest.
• Sometimes we see the lower layers through
holes in the upper ones.
• The Great Red Spot (GRS) has been seen by
Earthly observers for more than 300 years
• Infrared observations and the direction of its
rotation indicate that the GRS is a high-pressure
region whose cloud tops are significantly higher
and colder than the surrounding regions
• Jupiter has a huge magnetic field, much stronger than
Earth's
• Jupiter has 63 known satellites (as of Feb 2004): the four
large Galilean moons plus many more small ones some of
which have not yet been named.
Io
• Similar to terrestrial planets
• Active volcanoes
Europa
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Very young surface
Surface strongly resembles a sea of ice
Possible water 50 km deep
Life?
Ganymede
Callisto
Saturn
• Orbit: 1,429,400,000 km (9.54 AU) from Sun
• Diameter: 120,536 km (equatorial)
• Mass: 5.68 x 1026 kg
• Saturn was first visited by NASA's Pioneer 11 in 1979
and later by Voyager 1 and Voyager 2.
• Cassini (a joint NASA / ESA project) arrived on July 1,
2004 and will orbit Saturn for at least four years.
• Like Jupiter, Saturn is about 75% hydrogen and
25% helium with traces of water, methane,
ammonia and "rock”
• Saturn's interior is similar to Jupiter's consisting
of a rocky core, a liquid metallic hydrogen layer
and a molecular hydrogen layer.
• Saturn's interior is hot (12000 K at the core) and
Saturn radiates more energy into space than it
receives from the Sun. Most of the extra energy
is generated by the Kelvin-Helmholtz
mechanism as in Jupiter
• Saturn’s rings look
continuous from the
Earth, but they are
actually composed of
innumerable small
particles each in an
independent orbit.
• They range in size
from a centimeter or
so to several meters.
• A few kilometer-sized
objects are also likely.
• Saturn's rings are extraordinarily thin: though
they're 250,000 km or more in diameter they're
less than one kilometer thick.
• Despite their impressive appearance, there's
really very little material in the rings
• If the rings were compressed into a single
body it would be no more than 100 km
across.
• The ring particles seem to be composed
primarily of water ice, but they may also
include rocky particles with icy coatings.
• Saturn has 34 named satellites
• Mimas reveals evidence of a major impact
Uranus
• Pronunciation:
• Not to be confused with “urine us” or “your anus”
• Orbit: 2,870,990,000 km (19.218 AU) from Sun
• Diameter: 51,118 km (equatorial)
• Mass: 8.683 x 1025 kg
• Uranus has been
visited by only one
spacecraft, Voyager 2
on Jan 24 1986
• Uranus rotates on its
sides… so the poles
point directly towards
the sun.
• However, the equator
is still the hottest?!
• Uranus also has rings
Neptune
• After the discovery of Uranus, it was noticed that
its orbit was not as it should be in accordance
with Newton's laws.
• It was therefore predicted that another more
distant planet must be perturbing Uranus' orbit
• Because Pluto's orbit is so eccentric, it
sometimes crosses the orbit of Neptune making
Neptune the most distant planet from the Sun for
a few years.
• Neptune has been visited by only one
spacecraft, Voyager 2 on Aug 25 1989. Much of
we know about Neptune comes from this single
encounter
• Like a typical gas
planet, Neptune has
rapid winds confined
to bands of latitude
and large storms or
vortices. Neptune's
winds are the fastest
in the solar system,
reaching 2000
km/hour
• Neptune's most prominent feature was the
Great Dark Spot (left) in the southern
hemisphere.
• A small irregular white cloud zips around
Neptune every 16 hours or so - now
known as “The Scooter”.
• It may be a plume rising from lower in the
atmosphere but its true nature remains a
mystery
Pluto
• Orbit: 5,913,520,000
km (39.5 AU) from the
Sun (average)
• Diameter: 2274 km
• Mass: 1.27 x 1022 kg
• Pluto has a satellite,
Charon
New Horizons
• Early Cruise: The first 13 months include
spacecraft and instrument checkouts, instrument
calibrations, trajectory correction maneuvers,
and rehearsals for the Jupiter encounter.
• Jupiter Encounter: Closest approach occurred
Feb. 28, 2007. Moving about 47,000 miles per
hour (about 21 kilometers per second), New
Horizons would fly 3 to 4 times closer to Jupiter
than the Cassini spacecraft, coming within 32
Jupiter radii of the large planet.
• Interplanetary Cruise:
activities during the
approximately 8-year
cruise to Pluto include
annual spacecraft and
instrument checkouts,
trajectory corrections,
instrument calibrations
and Pluto encounter
rehearsals.
• You need pretty large
antennas to send data
over billions of miles and fortunately, NASA
has them.
The New Horizons
mission operations team
will communicate with the
spacecraft through
NASA's Deep Space
Network (DSN) of
antenna stations.
Information on the mission can be found at:
http://pluto.jhuapl.edu/index.php
Asteroid or Planet?
• There are some who think Pluto would be
better classified as a large asteroid or
comet rather than as a planet
• Further complicating the situation, one
such object (2003UB313) was recently
discovered that is almost certainly larger
than Pluto. Should it, too, be classified as
a planet?
• Dwarf Planet?
Kuiper Belt
• Distance: 30-100 AU from sun
• Consists of small, icy objects
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Dirty snowballs
878 known comets
Highly elliptical orbits
Dust tail--particles blasted off comet by sun;
always point away from sun
• Stardust mission approached comet in 1/04,
will return sample to Earth
Hubble Telescope
• The colors in Hubble images, which are
assigned for various reasons, aren't
always what we'd see if we were able to
visit the imaged objects in a spacecraft.
We often use color as a tool, whether it is
to enhance an object's detail or to
visualize what ordinarily could never be
seen by the human eye.
• http://hubblesite.org
Galaxies
• Spirals: They have a
central bulge with a
flattened disk,
normally depicting
spiral arms.
• Barred Spirals:
Almost same as
spirals but for the
existence of a bar in
the central region.
• Ellipticals: They are roundish non-flattened
galaxies. They generally have very little gas and
dust when compared with spiral galaxies. They
have few young stars, stars that were just
formed, with no spiral structure.
• Irregulars: Whatever galaxies that do not fall into
the first three classifications are hereunder.
• The Milky Way is the
galaxy which is the
home of our Solar
System together with
at least 200 billion
other stars (more
recent estimates have
given numbers
around 400 billion)
and their planets, and
thousands of clusters
and nebulae.
• As a galaxy, the Milky Way is actually a giant, as
its mass is probably between 750 billion and one
trillion solar masses, and its diameter is about
100,000 light years.
• The Halo consists of
the oldest stars known,
including about 146
Globular Clusters.
• The disk of the Galaxy
is a flattened, rotating
system which contains
the Sun and other
intermediate-to-young
stars.
• The sun sits about 2/3
of the way from the
center to the edge of
the disk
• The sun revolves
around the center of the
galaxy about once
every 250 million years
• The Milky Way Galaxy belongs to the
Local Group, a smaller group of 3 large
and over 30 small galaxies, and is the
second largest (after the Andromeda
Galaxy M31) but perhaps the most
massive member of this group.
The Majestic Sombrero Galaxy
(Messier 104)
Barred Spiral Galaxy NGC 1300
Andromeda Galaxy
The Universe…Where did it
come from?
• The Universe means all there is!
• The Big Bang Theory:
– It’s a model used to describe the creation of the
universe
– The universe was created in a violent event 10-13
billion years ago
– As a result, the universe is still expanding…
Evolution of the Universe
• Cosmologists are scientists who study the
evolution of the universe
– At the start: a dense fireball – a single point
– 3 minutes after the Big Bang: 500,000,000
degrees F or 277,777,760 degrees Celsius.
H & He form
– 50,000 yrs after Big Bang: atoms start to form
– 300,000,000 yrs after Big Bang: the universe
expands and is cool enough for galaxies to
form
Proof for the Big Bang
• Remember the Doppler Effect with sound?
• It works for light too!
• Light can shift it’s frequency depending on
the motion of the object that is emitting light
Proof for the Big Bang
•Edwin Hubble saw other galaxies in the 1920’s
•He noticed that the light from these galaxies wa
shifted to the red end of the spectrum.
•This means that all galaxies are moving away from
each other
•The universe is expanding
Proof for the Big Bang
• Cosmic Background Radiation
• light left over from the Big Bang shifted to
microwave wavelengths
• the whole universe has this after glow
Cosmic Background Radiation
The Future is Uncertain
• 1) The universe will expand forever
• 2) The expansion will slow down and the
universe will reach its limit
• 3) The universe will stop expanding and fall
back
• ** GRAVITY pulls in, EXPANSION pulls out
Nebula
• A planetary nebula is created when a star blows
off its outer layers after it has run out of fuel to
burn.
• These outer layers of gas expand into space,
forming a nebula which is often the shape of a
ring or bubble.
• At the center of a planetary nebula the glowing,
left-over central part of the star from which it
came can usually still be seen.
Hourglass Nebula
Red Supergiant Star V838
Moncerotis
• Black holes are the evolutionary endpoints
of stars at least 10 to 15 times as massive
as the Sun.
• With no outward forces to oppose
gravitational forces, the remnant will
collapse in on itself. The star eventually
collapses to the point of zero volume and
infinite density
• HDE 226868 is a B0 supergiant with a
surface temperature of about 31,000 K.
• Spectroscopic observations show that the
spectral lines of HDE 226868 shift back
and forth with a period of 5.6 days.