The sun is visible to us about _______ before the actual sunrise and about _______ after the actual sunset because of atmospheric refraction.

The correct answer is 2 minutes; 2 minutes.

Key Points

• The sun is visible to us about 2 minutes before the actual sunrise and about 2 minutes after the actual sunset.
• This phenomenon occurs due to atmospheric refraction.
• Atmospheric refraction causes the light from the sun to bend as it passes through the Earth's atmosphere.
• This bending of light makes the sun appear to be above the horizon when it is actually below it.
• Hence, we see the sun for a few minutes longer than its actual presence above the horizon.

Additional Information

• Atmospheric Refraction
  • It is the bending of light as it passes through the Earth's atmosphere.
  • This bending occurs because light travels at different speeds in different layers of the atmosphere.
  • The density of the atmosphere changes with altitude, causing the light to bend.
• Sunrise and Sunset
  • Sunrise is the moment when the upper limb of the sun appears on the horizon in the morning.
  • Sunset is the moment when the upper limb of the sun disappears below the horizon in the evening.
• Horizon
  • The horizon is the line where the earth's surface and the sky appear to meet.
  • It is an essential reference point for astronomical observations.
• Visual Effects
  • Due to atmospheric refraction, stars and planets also appear slightly higher than their actual position.
  • Twilight, the time before sunrise and after sunset, is also extended due to this effect.