Solution:
Earth rotates once in about 24 hours with respect to the Sun, but once every 23 hours, 56 minutes, and 4.9 seconds with respect to other, distant, stars.

Solution:
Contour lines are isolines joining places that have the same height value. Another common isoline is the isobar, a line that joins places with the same atmospheric pressure.

Solution:
The greenhouse effect is a natural process that warms the Earth’s surface. When the Sun’s energy reaches the Earth’s atmosphere, some of it is reflected back to space and the rest is absorbed and re-radiated by greenhouse gases.

Solution:
The time difference between each longitude (each degree) is 4 minutes. So if it is 12 noon at Greenwich (0°), it would be 12:04 pm at 1° meridian and so on.

Solution:
It takes 24 hours for the sun to go through the full 360° around the world, so an hour of time is equal to 15° of longitude.

Solution:
If a place is located at 20°N, 80°E it lies in Asia continent. The 20th parallel north is a circle of latitude that is 20° north of the Earth's equatorial plane. It crosses Africa, Asia, the Indian Ocean, the Pacific Ocean, North America, the Caribbean and the Atlantic Ocean.

Solution:
Sunlight travels at the speed of light. Photons emitted from the surface of the Sun need to travel across the vacuum of space to reach our eyes. The short answer is that it takes sunlight an average of 8 minutes and 20 seconds to travel from the Sun to the Earth.