If you compared the diameter of the Earth (13,000 km)to 1 second,what unit of time would be equivalent to the size of our Galaxy,whose diameter is ? __________,which is the length of time between now and when __________.
A) 3 million years;man's ancestors first began to walk upright
B) 30,000 years;humans first arrived in the Americas
C) 400 years;Galileo used a telescope to demonstrate that Jupiter had moons that revolved around it
D) 4 billion years;the Solar System was born

Question

If you compared the diameter of the Earth (13,000 km)to 1 second,what unit of time would be equivalent to the size of our Galaxy,whose diameter is  ? __________,which is the length of time between now and when __________.
A) 3 million years;man's ancestors first began to walk upright 
B) 30,000 years;humans first arrived in the Americas 
C) 400 years;Galileo used a telescope to demonstrate that Jupiter had moons that revolved around it 
D) 4 billion years;the Solar System was born

Quizplus · Accepted Answer

The size of our Galaxy is approximately 100,000 light-years, or 9.46e+17 kilometers. To compare this to the diameter of the Earth, we can use a ratio of 9.46e+17 km : 13,000 km. Simplifying this ratio gives us 7.28e+13, which is the number of times larger the Galaxy is than the Earth. Since we're comparing to 1 second, we can just multiply this number by the number of seconds in a day, year, or whatever unit of time we want to use. For example, multiplying by the number of seconds in a day (86,400) gives us about 6.28e+18 seconds. 4 billion years is also about 6.31e+17 seconds, so choice D is the best answer.

If You Compared the Diameter of the Earth (13,000 Km)to