Earth S Motions Guided Notes

Earth’s Motions Guided notes

Earth’s Motions

______, ______, and ______

Rotation - Earth turning or ______on an ______

·  The Earth rotates on its axis from W to E or ______!

Effects of Earth’s rotation…

·  We experience______as our location on Earth turns to the sun and night as it turns ______from the sun

·  When we look south, the Sun, stars, planets, & constellations appear to rise in the ______and set in the ______

·  Star trails look different in the northern sky than they do in the southern sky because:______

______

______

Effects of Earth’s Rotation: Coriolis effect

·  Because the Earth is ______at the equator, Earth rotates ______at the equator than it does at the poles

·  In the Northern Hemisphere winds, currents, airplanes, etc. appear to deflect to the right because ______.

·  Plane flights - pilots and navigators must compensate for objects veering to the ______

·  Space flights - Creates special problems for astronauts in space

·  Winds- Uneven ______of the atmosphere causes winds to blow from areas of ______pressure to areas of ______pressure

·  Distribution of ______ - If not for the ______caused by the rotating Earth, the equator would get constant rain and north & south would be deserts

Evidence that Earth Rotates: the Foucault Pendulum

·  A ball swinging back and forth on a string is called a ______.

·  In 1851, French scientist Léon Foucault observed that his pendulum seemed to ______.

·  Forces acting on a pendulum:

o ______causes it to swing straight out (Newton’s______Law of Motion)

o ______pulls it back ______(Newton’s Law of Gravity)

o Air resistance makes it swing in ______arcs (Friction is a force that acts against inertia)

Pendulum as Evidence that Earth rotates:

·  There is ______acting on the pendulum to make its plane of oscillation rotate

·  The pendulum seems to change its path during the day, but actually it is the ______ beneath it that changes, being twisted around by the daily ______of earth.

·  At the north pole the apparent rotation would be a full ______of 360 degrees each day, or about ______degrees per hour

Other evidence of Earth’s rotation:

·  Astronauts have observed Earth’s rotation from space!

Periods of Rotation of other Planets

·  Which two planets have the longest periods of rotation?

·  Which planet has the shortest?

·  Which planet’s period of rotation is almost the same as Earth’s?

Revolution

·  Earth revolves around the ______at an average speed of about 107,000 km/hr or 30 km/sec

Earth’s Orbit

·  We are closer to the Sun at ______(147 million kilometers) on about January 3rd and a little further from the Sun (152 million kilometers) at ______on July 4th

Evidence of Earth’s Revolution: Changing ______

·  As Earth moves along its orbital path, we face the sun from a different ______and we view different areas of space at ______

·  Most of the constellations we see in the summer are ______in the night sky during the winter.

·  This is evidence that Earth has ______locations in space!

Other Planets revolve on the same ______as Earth

Revolutions of other Planets

·  According to Kepler’s 3rd law, what is the correlation between a planet’s distance from the sun and its period of revolution?

______

Understanding Orbital Motion: The universal law of gravity allows us to understand orbital motion of planets and moons:

·  Earth and moon attract each other through ______.

·  Since Earth is much more ______than the moon, the moon’s effect on Earth is ______.

·  The moon’s ______would cause it to move in a ______line, but…

·  Earth’s gravitational force constantly ______the moon ______Earth

·  Gravity is constantly ______the moon’s direction of motion, holding it on its almost circular ______.

Precession

·  Earth’s “______” on its axis

·  Takes ~26,000 years to complete one wobble

What causes Precession?

·  The Earth is slightly ______

o  it bulges in the middle

o  ~0.34% larger at equator due to its ______and the fact that it is not completely rigid.

·  The Sun and Moon exert ______gravitational forces on the Earth, pulling harder on the ______side of the bulge than on the far side. (gravity weakens with ______)

Consequences of Precession

·  What happens as one consequence of precession?

______

______

______

Earth’s Motions and Time

·  There are various ways to define units of time like a day or a year…

o  Sidereal (or star) day:

o  It takes the earth 23 hours and 56 minutes to rotate once with respect to the ______

o  Solar day

o  During this time, the earth has ______a bit along its ______around the Sun. So…

·  It takes about 4 minutes longer for the ______to return to the same position in the sky

·  Because we use the ______day, the stars rise and set 4 minutes ______each day.

Focus Questions:

How do the motions of the Earth affect our observations?

How are Earth’s motions related to our definition of time?