The Sun and all that orbits it.• Formed from a nebula• About 5 billion years old• The Sun contains 99% of

the mass of the solar system

The Solar System

8 planets: MVEMJSUN: My very enormous mother just sent up nachos. Planet Distance

Asteroids: 100-1,000 km in diameter. Mostly found between Mars and Jupiter. Possibly a destroyed planet.

Meteoroids: Small space debris. Often found in the paths of comets which we pass through causing meteor showers. Meteors=Meteoroids in Earth’s atmosphere. Meteorites=Meteoroids on the ground.

Comets: 1-100 km in diameter. Huge ice balls composed of frozen gases like methane, rocks, metal chunks. Haley’s Comet orbits Sun once in 76 years.

Dwarf Planets: Ceres, Pluto and Eris

Satellites of the Sun

Close Call

Asteroids

Geminid Meteor Shower

Leonid Meteor Shower

The Leonid shower that occurs every November is an event caused by the Earth passing through an especially dusty area of space.

The extra dust is there because the orbit of the Temple-Tuttle comet passes near Earth's orbit every 33 years and leaves behind a dusty trail.

To view the Leonid shower, you just go outside at the appropriate hour, look toward the constellation Leo (hence the name "Leonid") and you should be able to see shooting stars occurring several times per minute!

More on the Leonid Meteor Shower

Haley’s Comet 1986

Comet Hale-Bopp

1-Terrestrial Planets: The 4 closest to the sun. All are relatively small and have solid surfaces made of rock. Few or no satellites. (Moons: 0,0,1,2 respectively)

2-Jovian Planets: Far from the Sun, largely gaseous, large diameters, low densities, no solid surfaces but may have solid cores, many moons and rings. (Moons: 63, 56, 27, 13 respectively)

There are Two Types of Planets

1. Spiral motion around the center of the Milky Way Galaxy. Once in 225 million years.

Motions of the Planets

2. Rotation: To spin on an axis. All planets rotate W to E except Venus which has retrograde rotation, E to W. The Earth day is based on this motion. See ESRT. Rotation in MPH

3. Revolution=orbit=revolve: The Earth year is based on this motion. All planets go around the Sun in an elliptical Path (Oval.) Kepler’s First Law! How oval? Use the eccentricity equation:

E= Distance between foci Length of Major axisAnswers have no units. 0=Perfect Circle, 1= straight line

More motions:

More on Eccentricity

L

Length of Major AxisThe fattest part of the ellipse. Always passes through foci.

Distance between Foci

Earth’s Eccentricity

147 million km

152 million km

Distance between foci = 152 million km- 147 million km= 5 million kmLength of major axis=152 million km + 147 million km= 299 million kmUsing the equation E= d LE= 5 million Km = 0.017 (no unit for eccentricity) 299 million Km

Calculating the Earth’s Eccentricity

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0Circle very oval flat line

Our orbit is very close to a perfect circle!

So how eccentric is our orbit?0.017 for Earth’s eccentricity

No planet stays at a constant distance from the sun

The Earth is closest to the Sun on January 3rd. This date is called the perihelion.

The Earth is farthest on July 4th, called the aphelion.

The moon does the same being closest at perigee and farthest at apogee. Dates are not constant for the moon.

We are closer to the sun during the winter, so it has little effect on our temperature! It does look slightly bigger if you compare a photo to one from Jan 3rd.

The Elliptical Orbit of the Planets

Inertia and Gravity: The fight between these 2 forces keeps us in orbit around the Sun. Without gravity inertia would take us into space, w/o inertia, gravity would pull us into the Sun…can you say fry daddy?

Gravity: When we are closest to the Sun it pulls on us harder so we move faster in our orbit at that time. When we are farther, there’s less pull, therefore slower orbital velocities. Our orbital velocity is NOT constant!

Inertia, Gravity, Orbital Velocity, and a Planets Orbit

Diagram (Very Exaggerated!!!)

Sun

Earth Earth

Fastest orbital Velocity Slowest Orbital Velocity

decreasing

increasing

Kepler’s Second Law: Kepler found that the Earth SWEEPS out the same area of space in an equal time periods.

Defined as the length of time it takes a planet to revolve around the sun. See ESRT

Kepler’s 3rd Law: The farther a planet is from the sun, the longer it will take to revolve. DUH! But Mathematically proven!

Planet Period

How celestial objects appear to move.Caused by the Earth’s rotation!Due to the rotation of the Earth, objects

appear to move across the sky at 15 degrees/hour from East to West. (Earth rotates 15 degrees/hr. West to East)

Daily Motion looking South.

Apparent Motion of Celestial Bodies

Appear to revolve around Polaris at 15 degrees/hr.

The path a star follows is called an arc. An arc is a portion of a circle. If you could do a time lapse photo for 24 hours, a complete circle would be made.

Circumpolar stars follow paths that could be completely seen above the horizon. All the others rise in the East and set in the West.

Stars

Daily, move like stars.Over longer periods (weeks, months) they will

be in a different place with respect to the star field behind them. BECAUSE THEY ARE REVOLVING AROUND THE SUN!

Motion of planets: GO TIME

Planets

Moves like the stars.Rises 50 minutes later each night and shifts

eastward compared to the star field behind it.

Moon

Earth’s only natural satellite386,000 km (~240,000 mi.) from EarthRevolves once around Earth in 27.3 DaysRotates once in 27.3 daysWe can only see one side from the Earth because

it’s rotational period is the same as it’s revolutionary period.

Orbital Eccentricity is 0.055 (Apogee/Perogee)Equatorial Diameter=3,476 km

The amount of the sunlit side of the moon visible from Earth.

A cyclic event. A full cycle (like full to full) 29.5 days. Why

is this not the same as a period of revolution?

Caused By: 1) Moon’s revolution around the Earth2) Reflection of sunlight from its surface. Half

the moon is always in daylight. We see varying amounts of the lit half to the moons position around us and where the sun is.

Moon Phases

Moon Phase Diagram

EclipsesTides

Moon’s affects on Earth

Occurs during a NEW MOON phase when the MOON passes between the Earth and Sun during the day

Happens during the day so the Moon blocks out the sun

Only seen in it’s entirety on a small part of the Earth

Solar Eclipse

Occurs during a FULL MOON phase when the EARTH passes between the Sun and the Moon

Moon passes through Earth’s shadow (Umbra: dark part of the shadow and Penumbra: lighter part of the shadow)

Happens at night so it is seen across the entire dark side of the Earth

Lunar Eclipse

Earth/Moon /Sun Positions

Cyclic rise and fall of the ocean waterOccur twice a dayCaused by Moon’s Gravity with some help

or hindrance from the sun2 high tides and 2 low tides each day12 hr and 25 min. from high tide to the

next high tide

Tides

Highest high tides, lowest low tides

Sun/Moon/Earth are in a straight line (Sun Helps!)

Occurs during two moon phases or twice a monthNew Moon: Sun/Moon/EarthFull Moon: Sun/Earth/Moon

Spring Tides

Lowest high tide, highest low tide.

Sun/Moon/Earth make a 90º angle (Sun hinders)

Occurs during 2 phases each month1st QuarterThird Quarter

Neap Tides