Why do astronomers think that there may be other advanced civilizations?

What technologies are astronomers using to look for life on other planets? Why?

What are the challenges of looking for Dyson spheres?

Astronomers have theorized that there could be three types of civilizations. What are they? How would they be recognized? Which one has been ruled out so far?

Do you think an advanced civilization may exist in the universe? Why or why not?

PLZ help :)

__1__ is a climate cycle where the temperature of the __2__ ocean changes because of movements of air and ocean currents. during this period, the trade winds in the south __3__ , causing the __4__ water to move from the __5__ region to the __6__ region. 1) el nino or the monsoon 2) atlantic, indian, or pacific 3) reverse, strengthen, or weaken 4) cold or warm 5) eastern or western 6) eastern or western

Which flexible structure that supports the nerve cord and led to the backbone

1. emigration the movement of people from one place to another 2. immigration a situation in which resources are being used up at a faster rate than they can be replenished 3. migration the leaving of one's homeland to settle in a new place 4. overpopulation the movement of people to a new country 5. sustainable development a situation in which the birth rate is not sufficient to replace the existing population 6. underpopulation the ability to meet current needs without reducing the ability to meet future needs 7. unsustainable development the increase in the population of a city 8. urbanization a situation in which the number of people exceeds the available natural resources in an area