Download Earth and the Universe Name

Earth and the Universe
Name: _____________________________________________________________ Period: _____ Date: ________
EQ: How do the Earth’s location in space, rotation, revolution, precession, and nutation affect the seasons?
The universe is made up of many galaxies. Galaxies are made up of many stars. Some stars have planetary systems
similar to our solar system. Earth is a satellite planet of one particular star…. our Sun.
Our solar system is located in the Milky Way Galaxy. The Milky Way is part of a cluster of about 30 other galaxies.
The Milky Way Galaxy: The central bulge is at the center. Spiral arms are around the central bulge. They contain
mostly blue stars, gas and dust. The Solar system and Earth are located in one of the spiral arms. Earth is the 3rd
planet from the Sun in our solar system. There are blue stars and red stars in our galaxy. Blue stars are young and hot
stars. Red stars are old and cooler stars.
Earth is an oblate spheroid. It is wider at the equator than at the poles. This is caused by the rotation of the Earth on
its axis. The Earth’s axis is an imaginary line that runs through the center of the Earth from the north pole to the
south pole. The Earth is “tilted” with relation to this imaginary line 23.5⁰. The Earth’s tilt is responsible for the
seasons. The Earth’s movement around the Sun is called a revolution, one complete revolution is equal to 365.25
days. The revolution and the tilt are the main causes of the seasons.
Rotation: One rotation about the Earth’s axis takes 24 hours. This is called a day. Rotation about the Earth’s occurs
from west to east. (Counter clockwise) Earth’s rotation is the cause for day and night and Coriolis effect.
Precession: The rotation of the Earth’s axis is called precession. The angle remains the same. This will affect the stars
near the poles. Precession does not change the seasons as long as the 23.5⁰ tilt stays the same but it changes Earth’s
northern star every few thousand years.
Nutation: The “wobble” about the precessional axis is called nutation. Nutation is a change in the in the angle of tilt
by ½ ⁰ one way or the other. Results in the tilt either being 23⁰ or 24⁰. This occurs over an 18 year period. This is due
to the Moon. This causes a slight change in the seasons.
Barycenter: A barycenter is the point between two objects where they balance each other. It is kind of like the center
of gravity. The center of gravity is the point in the middle of all the material that makes up an object, mass. When a
moon orbits a planet, or a planet orbits a star, both bodies are orbiting around a point that lies outside the larger
body. The moon does not orbit the exact center of the Earth, but a point about 1710 km below the Earth’s surface.
The sun is not stationary in the solar system. It moves as the planets tug on it, but it never gets too far from the solar
system barycenter.
Kepler’s Three Laws of Planetary Motion: Johannes Kepler was a German mathematician, astronomer and
astrologer. He was a key figure in the 17th century scientific revolution. Kepler’s Laws describe the motion of the
planets around the sun. Kepler knew of 6 planets: Earth, Venus, Mercury, Mars, Jupiter and Saturn.
Kepler’s First Law: States that planets move around the sun in ellipses, with the sun at one focus. What
does this really mean? This means that the distance between the planet and the sun varies, as the planet goes
around.
Kepler’s Scond Law: Each planet moves around the Sun so that an imaginary line joining the planet and the
Sun will sweep over equal areas in time. This means that because the orbits are elliptical, the planet’s travel
at different speeds at different positions in the orbit. When planets are closer to the sun they are faster.
Kepler’s Third Law: The farther a planet is from the Sun, the longer it takes to make one complete revolution.
Clarifying Questions:
1. The universe is made up of _______________________________________________________________________.
2. Galaxies are made up of _________________________________________________________________________.
3. Earth is the satellite planet of the __________________________________________________________________.
4. The Milky Way Galaxy is _________________________ and ___________________________________________.
5. The Solar system and Earth are located _____________________________________________________________.
6. What is the difference between blue and red star? ____________________________________________________.
7. How does our star compare to the blue and red stars based on age?______________________________________.
8. The shape of Earth is _______________________________________________________.
9. What is an oblate spheroid? _______________________________________________________________________.
10. Why is the Earth’s shape oblate spheroid? __________________________________________________________.
11. The Earth’s axis is ______________________________________________________________________________.
12. Revolution is ____________________________________________________ and takes _________________ days.
13. The revolution and the tilt are ____________________________________________________________.
14. Earth’s rotation takes ________ hours and causes ___________________ and _______________ effect.
15. Precession is ______________________________________________________________ and affects the
_______________________________________________________________________________________.
16. Earth’s northern star changes every few thousand years because of ______________________________.
17. Nutation happens when _________________________________________________________________.
18. Unlike precession, nutation causes a slight change in the seasons because ________________________.
19. Barycenter is __________________________________________________________________________.
20. The point where the moon orbits around Earth is located _________________________________. This is
called ________________________. The barycenter is always closer to the _____________________ body.
21. The Sun is not stationary in its place because________________________________________________.
22. Johannes Kepler was ___________________________________________________________________.
23. There are ______ laws describing Kepler’s Planetary Motion.
24. Kepler’s First Law states that _____________________________________________________________.
25. Kepler’s Second Law states that ___________________________________________________________.
25. Kepler’s Third Law states that ____________________________________________________________.
26. Elliptical means ________________________________________________________________________.
27. Planets orbit around the Sun in an ___________ orbit and they are faster when they are _____________.
R.Angat