If you stacked avogadro's number of pennies one on top of the other on earth's surface, how far would the stack extend (in km)? [for comparison, the sun is about 150 million km from earth and the nearest star (proxima centauri) is about 40 trillion km from earth.]

the length of pennies will be like the Proxima Centauri

Explanation:

50 pennies make the length of a meter, so :

50 pennies = 1 m

   x               = 1 km  

x= (50 x 1000) = 50 000 pennies = 1 Km

Then if the Avogadro´s number is 6.022 x 1023 so:

50 000 pennies = 1 km

6.022 x 1023 pennies = x

x= (6.022 x 1023/ 50 000) = 1.2044 x 1019

This big number is closer to the 40 trillion km of the Proxima Centauri.

Hope this answer is useful.

brave new world, aldous huxley (1932)

it is very hard for the climatologists to precisely predict how will the global temperatures be changing so there's lots of models, some of which differ significantly, this is due to multiple factors, and probably the most important is the human activity.

humans have been a key factor in climate change around the globe since the start of the industrial revolution, and in the past few decades the consequences are becoming more obvious. there's lots of emission of pollutants in the atmosphere as well as changing the environment on the surface itself, so it's really hard to predict how will that go in the future because there's some countries that are reducing the damage and are going towards green energy, while others are stubbornly continuing with pollution and damages to the environment.