Answer:
Saturn. Saturn's rings are the most extensive ring system of any planet in the Solar System, and thus have been known to exist for quite some time. Galileo Galilei first observed them in 1610, but they were not accurately described as a disk around Saturn until Christiaan Huygens did so in 1655.
Explanation:
That's right, Venus (and the planet Mercury) are the only two planets that don't have a single natural moon orbiting them. Figuring out why is one question keeping astronomers busy as they study the Solar System.
1. Introduction of non native species into stable ecosystems.
Answer:
Immigrants may be defined as the individuals that comes from some other country but are the permanent resident of some other country. The individual might move for the jobs and education.
The immigrants might flock to the urban neighborhood and can settle on the basis of the their ethnicity. These neighborhood provide jobs to the immigrants and they had poor working conditions. The immigrants were underpaid. The mutual aid societies are formed in which immigrants pay dues and and the society pay for their elevation. The Americans and immigrants suffers from the pollution, crime and overpopulation.