Question

Which statements are true regarding the circle of illumination and Earth's orbit around the sun?

1. The circle of illumination divides the day from night on the globe
2. It takes 366 days for the Earth to revolve around the sun.
3. Earth goes around the sun in a perfectly circular orbit.

• A. 2 only
• B. 2, 3
• C. All
• D. 1 only

Answer 1

Answer:

D. 1 only

The Circle of Illumination

• The Circle of Illumination represents an imaginary line that demarcates the Earth into two distinct hemispheres.
• On one side, which faces the Sun, there is illumination and thus daytime, while on the opposite side, in shadow, there is darkness or nighttime.
• The Circle of Illumination precisely separates these two halves.
  
  
• The Circle of Illumination is in constant motion due to the Earth's rotation.
• Consequently, this dynamic boundary is responsible for the continuous transition between day and night.
• As the Earth revolves, the Circle of Illumination traverses its surface.
• When this boundary passes over a particular geographic location, it designates daytime for that region, and as it moves away, it designates nighttime.

Days for the Earth to complete one orbit around the sun

• It takes approximately 365.25 days for the Earth to complete one orbit around the sun
• Six hours saved every year are added to make one day (24 hours) over a span of four years.
• This surplus day is added to the month of February.
• Thus every fourth year there is a leap year with 366 days.

Earth's orbit around the Sun

• Earth's orbit around the Sun is not perfectly circular; it is elliptical.
• An elliptical orbit means that the path Earth follows as it revolves around the Sun is slightly elongated and resembles an ellipse, or an oval shape, rather than a perfect circle.\
• This elliptical shape causes Earth's distance from the Sun to vary slightly throughout the year.
• At certain times in its orbit, Earth is closer to the Sun, which is known as perihelion, while at other times, it is farther from the Sun, known as aphelion.
• This variation in distance does have some impact on our climate and seasons, but the tilt of Earth's axis remains the primary driver of seasonal changes.