Transcript Astronomy Part 2- PowerPointx

Astronomy Part 2
By Sahithi And Morgan
2.1 Formation of the sun and the planets
The Nebular Hypothesis was that our Solar System
formed from a spinning cloud of gas and dust. This
nebula was drawn together by gravity. As particles
began to come together in the center, it released
kinetic energy and gravity increased. Today's planets
were caused by the collision and collection of particles.
This process is called accretion. This process first
created Planetesimals. Planetesimals are nothing but
baby planets or beginning planets.
2.2 Minor Members of our Solar System
There are three types of minor members in our solar
system, Asteroids, Meteors and Comets. Asteroids
are small, rocky bodies that orbit the sun. Asteroids
mainly lie between Mars and Jupiter. This ring of
Asteroids divide the inner and the outer planets.
Asteroids didn’t become planets due to the
gravitational pull of Jupiter.
2.2 Minor Members of our Solar System
Meteors are a chunk of space debris that enters
Earth's atmosphere and burns up, creating a
streak of light. Meteors are the ones that are in
the atmosphere. Meteoroids are a chunk of
space debris, smaller than Asteroids, that hasn’t
yet reached the Earth's atmosphere. Meteorite
is a large meteoroid that strikes the Earth's
surface. These are all the same thing except
that they are based on their location.
Remember, if it hits the earth, it's meteorite, if
it doesn’t hit the earth, its meteor-WRONG.
2.2 Minor Members of our Solar System
Halley’s Comet
Comets are small, icy objects that have very
elliptical orbits around the sun. Comets are also
called dirty snowballs. Comets may have brought
water and other materials when in collision. A
comet's tail always points away from the sun due
to solar wind. There are two types of comets: Short
period and Long period. Short period comets come
from the Kuiper Belt and Long period comets
come from the Oort Cloud. Both of these are
located outside the orbit of the planet Neptune.
One example of a comet is the Halley’s Comet. It
is expected to appear again in 2061.
2.3 & 2.4 Revolutions and Rotations of the Earth
Geocentric Model
Johannes Kepler
The Geocentric Universe: The ancients believed that the
universe revolved around Earth. The word "Geo" in
Geocentric means Earth and the word "Centric" means
center. Hence, Earth centered.
The Heliocentric Universe: About 1500 years later, Nicolaus
Copernicus made a model of the universe that placed the
Sun in the center. The word "Helio" in Heliocentric means
the sun. Johannes Kepler later perfected it with his 3 laws
of Planetary Motion. The three laws were that the planets
orbit in ellipses and not in circles, Planets orbit faster when
closer to the Sun and Calculated the time it takes a planet
to orbit.
2.3 & 2.4 Revolutions and Rotations of the Earth
Earth's Revolution- A year has 365.24 days.
The Leap Year makes up the .24 of the day
from the four years. Perihelion is the point
where the Earth is closest to the Sun. Aphelion
is the point where the Earth is farthest from
the Sun.
Earth's Rotation- Earth rotates on its Axis, an
imaginary line through the center of Earth
from pole to pole. One rotation takes 24 hours
(1 day). Everything in the sky appears to rise
from the East and set in the West.
2.5 The Precession of the Earth's Axis
Earth's axis is tilted about 23.5 degrees and
does not remain stationary. The axis wobbles
very slowly like a top. This wobble is called
Precession. The cause of the precession is
the bulge at the equator of the Earth. Earth
is not a perfect sphere, it is slightly fatter at
the equator. Hence, the Earth is called an
Oblate Spheroid. The angle of the axis also
varies slightly. This type of wobble is called
Nutation.
2.6 Seasons
2.6 Seasons
 Four Seasons- Winter, Spring, Summer and Fall
 Seasons are NOT caused by how close the Earth is to the
Sun.
 Solstice is when the Sun reaches the highest or lowest
point in the sky at noon, marked by longest and the
shortest days.
• Summer: June 20/21
• Winter: December 21/22
 Equinox is the time or date(twice a year) at which the
Sun crosses the celestial equator, when day and night are
equal.
• Vernal: March 20
• Autumnal: September 22/23
2.7 & 2.8 Moon and its Phases
Moon is less dense and less massive than the Earth. Gravity in the
Moon is 1/6 of the gravity in the Earth. The moon revolves around
Earth every 27.3 days. The moon also rotates the same amount of
days. Due to this, we only see one side of the Moon. There is no
atmosphere but there are different types of surfaces on the Moon.
 Craters: Large, bowl-shaped cavities caused by impacts,
such as asteroids
 Maria: Large, level basalt plains on the surface of the
moon, appearing dark by contrast with highland areas
 Terrae(highlands): Light-colored, rough upland or
mountain regions
 Regolith: The layer of loose rock and dust that covers
the surface
2.7 & 2.8 Moon and its Phases
Waxing: Illuminated
area is “growing” right
to left
Waning: Illuminated
area is “growing” right
to left
Gibbous: greater than
half
Crescent: less than
half
The Phases of the Moon is caused by the
Sunlight and the Earth’s position.
2.9 Eclipses
Solar Eclipse: Moon is b/w Earth and Sun. This
type of eclipse always occurs during a new
moon. Only one small area on Earth is visible.
There are three types:
Total Solar Eclipse: Sun is fully covered by
the Moon
Annular Solar Eclipse: Sun and Moon are
lined up but the Moon looks smaller than the
Sun
Partial Solar Eclipse: Sun is partially covered
by the Moon since they aren’t all lined up.
2.9 Eclipses
Lunar Eclipse: Earth is b/w Moon and Sun.
This type of eclipse always occurs during a
full moon. This eclipse can only be seen by
people on side of the Earth that is facing the
Moon. Eclipses don’t happen every month
b/c the Moon’s orbit is a bit off.
Umbra: Total shadow
Penumbra: Partial shadow
THE END! 