Transcript the planets - St John Brebeuf

11.2 The Sun and the Planets
See pages 382 - 383
Our Sun, an average star in the universe, is the center of our
solar system.
1) Our solar system is full of planets, moons, asteroids and comets, all of
which revolve around the Sun at the center.
2) When a star forms from a nebula, gravity pulls most of the material
into the new star, but some may also clump together to form objects
in a solar system.
a)
A planet is a celestial body that orbits one or more stars.
b)
Each planet may also spin on its axis (rotates) while it orbits the Sun
(revolves).
3) Our solar system formed approximately 4.5 billion years ago.
4) The four inner (rocky) planets formed in the first 100 million years on
the Sun’s existence, while the outer (gas) planets formed later from
the remnants of the Sun’s original nebula.
See pages 383 - 384
THE SUN
1)
2)
3)
contains 99% of all the mass found in our solar system.
has a diameter equal to 110 Earths.
made up mostly of hydrogen.
The hydrogen molecules
-are forced to join together through massive gravity
-form new helium molecules, then
-release huge quantities of energy as light and heat
through the process of thermonuclear fusion.
4)
5)
6)
7)
has no solid surface
has distinctive features such as sun spots, flares, and prominences.
The photosphere is the surface of the Sun. It looks blotchy due to rising
and cooling gases.
The corona is the outer portion of the Sun’s atmosphere.
SOLAR WINDS
See page 385
Sometimes, gases from the
Sun’s corona erupt outwards
like a bursting soap bubble.
1) The resulting solar wind is full of high-energy particles that would kill any life
on Earth they struck.
2) Luckily, our magnetic field deflects this solar wind. We can see these particles
being deflected when we see the Northern Lights.
3) Large outbursts of solar winds can wreak havoc with satellites as well as
Earth-bound energy supplies such as power plants.
THE PLANETS
See pages 385 - 387
1)To be considered a planet, a body must
a) orbit one or more stars,
b) be large enough that its own gravity holds it in a spherical shape, and
c) be the only body occupying the orbital path.
2) Distances between planets in the solar system are measured in
astronomical units (AU).
-One AU = the average distance from the Sun to the Earth.
a) The inner planets are relatively close to the center of the solar
system
I. Mars is 1.52 AU from the Sun.
II. The next planet, Jupiter, an outer planet, is 5.27 AU from the
Sun.
III. The most distant planet, Neptune, is 30.06 AU from the Sun.
Inner, rocky planets
Outer, gaseous planets
Mercury
Smallest planet
Jupiter
Largest planet
Venus
Earth’s sister
Saturn
Rings + many moons
Earth
Only life in universe
Uranus
Methane gas planet
Mars
The red planet
Neptune
Outermost planet
OTHER SOLAR SYSTEM BODIES
See pages 388 - 389
There are also numerous celestial bodies smaller than planets in our solar system.
Moons are found around all planets except Mercury and Venus.
Asteroids are found mostly between Mars and Jupiter in the asteroid belt. It
is thought these are ‘leftovers’ from the formation of the solar system.
This picture of the rocky asteroid
951 Gaspra was taken by NASA's
Galileo spacecraft.
Image Credit: NASA
The Kuiper Belt is a disk-shaped region past the orbit of Neptune,
roughly 4,400,000,000 to 14,900,000,000 km (30 to 100 AU) from the Sun, that
consists mainly of small bodies which are the remnants from the Solar System's
formation.
It also contains at least one dwarf planet - Pluto. Pluto is indeed now
considered to be a member of the Kuiper Belt - the largest object belonging to
it, in fact! Like other members of the Belt, it is composed primarily of rock and
ice and is relatively small.. The Kuiper Belt is also believed to be the source for
short-period comets (ie, those that take less than 200 years or orbit).
http://heasarc.gsfc.nasa.gov/d
ocs/cosmic/solar_system_info.
html
Comets
(sometimes called “dirty
snowballs”) are actually rocky
travelers, following huge orbits
far outside the planets in the Oort
Cloud.
Trans-neptunian objects refer to objects outside
Neptune’s orbit, including ex-planet Pluto (now
referred to as a dwarf planet). These objects orbit
the Sun in a large area known as the Kuiper Belt.
The Oort Cloud
In 1950, astronomer Jan Oort proposed that long-period comets reside in a vast
spherical cloud residing 50,000 to 50,000+ AU from the Sun, at the outer reaches of the
Solar System. This major reservoir of comets has come to be known as the Oort Cloud.
http://heasarc.gsfc.nasa.gov/docs/cosmic/solar_system_info.html
The Kuiper belt can be
described as disc or
doughnut-shaped, but the
Oort cloud is more like a very
thick "bubble" that surrounds
the entire solar system,
reaching about half-way from
the Sun to the next nearest
star. Statistics imply that it
may contain as many as a
trillion (1012) comets.
Unfortunately, since the
individual comets are so small
and at such large distances,
we have no direct evidence
for the Oort Cloud. The Oort
Cloud is, however the best
theory to explain how longperiod comets exist.
The Oort Cloud is at the farthest reaches of the
Sun’s gravitational pull, almost 25% of the way
to the next nearest star, Proxima Centauri.
https://www.youtube.com/watch?v=ZDaFQsdNNgU
http://herschel.jpl.nasa.gov/solarSystem.shtml
Artist’s
rendering
of the
Kuiper Belt
and Oort
Cloud.