How did ancient Greeks such as Aristotle know that Earth is round?
A) From the ancient manuscripts of authors such as Homer.
B) By noting that ships drop below the horizon as they go out to sea.
C) By triangulation (measuring the distance between 2 points, and measuring 2 angles, to determine the distance to a 3rd point).
D) Careful measurements of the distance, along Earth's surface, between two widely separated points showed it to be longer than the straight-line distance.
E) Actually, the ancient Greeks thought that Earth is flat.
Question 2
A rocket is moving at 1/4 the speed of light relative to Earth. At the center of this rocket, a light suddenly flashes. To an observer at rest in the rocket
A) the light will reach the front of the rocket at the same instant that it reaches the back of the rocket.
B) the light will reach the front of the rocket before it reaches the back of the rocket.
C) the light will reach the front of the rocket after it reaches the back of the rocket.
Uranus's aurorae against its equatorial rings, imaged by the Hubble telescope. Unlike the auror
The Tilt of Earth’s Axis
How to round numbers with significant digits
Earth’s Biomes "الأرض الحيوية"
Earth Atmosphere
Relative Sizes of Dwarf Planets and Earth