Question

cyanobacteria and small ______ caused oxygen levels to increase.
the ______ layer developed to block out uv rays.

earth’s oceans
+ as the atmosphere developed, earth was cooling enough for ______ to form.
+ 3 to 3 ½ billion years ago water vapor began to condense and rain formed ______.
+ ocean water absorbed much of the ______ (co₂) from the atmosphere.
+ by 1 ½ billion years ago, the chemical composition of the atmosphere was ______ to what it is today.

geocentric model
+ ______, a greek philosopher thought the solar system looked this way.

• the sun, stars, and the planets revolved around the ______.
• didn’t explain why some planets appear to reverse direction occasionally = retrograde motion.

ptolemy’s model
+ proposed a model of the universe in which each planet had 2 motions.

• 1. ______.
• 2. movement by a series of small circles called ______.

◊ would make it appear to move ______ at times.

heliocentric model
+ copernicus proposed a heliocentric, (______ - centered) model of the solar system, in the 1500s.
+ planets orbit in the same direction but move at different ______ and distance from the sun.
+ confirmation in the early 1600s, galileo ____ was able to observe the motions of the planets with the newly developed ____.

law of ellipses law #1
+ states that each planet orbits the sun in a path called an ______.
+ an ellipse is an ______ whose shape is determined by 2 points within a figure.

• each point is a ______ (plural: foci).
• the ______ is at 1 focus of the orbit of a planet.

+ if you draw a line from any point on the ellipse to each of the 2 foci, the total length of the lines will always be the ______.
+ the point where the orbit is closest to the sun is the ____, the point where its farthest from the sun is ____.
+ the average distance between the earth and the sun is known as 1 astronomical unit or ______.

• 1 au = 93 million miles (150 million km).

law of equal areas law #2
+ describes the ______ at which planets travel at different points in their orbits.

• kepler found that the orbit of the earth was a nearly perfect ______, with the sun off - center.
• earth moves fastest when ______ to the sun.
• calculated that a line from the center of the sun to the center of a planet sweeps through equal ____ in equal periods of ____.

+ states that the area of the long, thin sector is the same as the area of the short, wide sector.

law of periods law #3
+ describes the relation between the average distance of a planet from the sun and the ______

Explanation:

Cyanobacteria and small plants perform photosynthesis, increasing oxygen levels. The ozone layer blocks UV - rays. As Earth cooled, water vapor condensed to form oceans. Oceans absorbed carbon - dioxide. By 1.5 billion years ago, the atmosphere's composition was similar to today. In the geocentric model, Aristotle thought the solar system was Earth - centered. Ptolemy's model had planets with circular motion and epicycles. Copernicus' heliocentric model was sun - centered. Planets move at different speeds and distances. Galileo used a telescope to observe. Planets orbit in ellipses, which are ovals with foci. The sun is at a focus. The closest point to the sun is the perihelion, the farthest is the aphelion. Kepler's laws describe orbital speed, area swept, and the relation between distance and period.

Answer:

1. plants
2. ozone
3. oceans
4. oceans
5. carbon - dioxide
6. similar
7. Aristotle
8. Earth
9. Circular motion
10. epicycles
11. backward
12. sun
13. speeds
14. Galileo
15. telescope
16. ellipse
17. oval
18. focus
19. sun
20. same
21. perihelion
22. aphelion
23. AU
24. speed
25. ellipse
26. closest
27. areas
28. time
29. period