Well dumping is a method, waste materials are dumped in open low labs away from the city.
The moon makes one full rotation around the earth every month (29.53 days). This means that it makes one 360 degree rotation every ~30 days, which is 12 degrees of movement per day.
Since the earth rotates once every day, so it makes one 360 degree rotation every 24 hours.
To determine how many 'hours' later 12 degrees is, do: 12 degrees / 360 degrees * 24 hours(in a day) = .8 hours, which if you multiply by 60 you get 48 minutes.
Around 400 million years old
Answer: 
Explanation:
The Tropic of Cancer is one of the parallels (imaginary line around the Earth parallel to the equator) located in the northern hemisphere (currently its latitude is 
).
It is called "Cancer" because a long time ago, when the summer solstice occurred in the northern hemisphere (on June 20th or 21st), the Sun was in the constellation Cancer (the crab).
Now, if we were just in the North Pole, Polaris would by exactly over our heads (
over the horizon), but as we go south and find the Tropic of Cancer parallel, Polaris altitude will be approximately at an angle of over the horizon.
Hence, the altitude of Polaris measured by an observer at the Tropic of Cancer is .
