What is the meaning of the solar constant?
A) the regularity of the 11-year sunspot cycle
B) the amount of energy the Earth receives per unit area and unit time
C) the stability of the Sun's luminosity for as long as life has existed on Earth
D) the fact that features on the Sun appear to never change
E) the fact that the amount of hydrogen turning into helium in the core is fixed
Question 2
Ptolemy was important in the history of astronomy because he ________.
A) was the first to believe that all orbits are perfect circles
B) was the first to create a model of the solar system that placed the Sun rather than the Earth at the center
C) developed the first scientific model of the universe
D) developed a model of the solar system that made sufficiently accurate predictions of planetary positions to remain in use for many centuries
Leaf structure and its relationship to the C4 cycle
Origin of a Solar Flare
Menstrual cycle
Effects of Earth’s Changing Orientation: Solar Angle
Overview of the Solar System