Answer: Global warming is happening because the greenhouse gases are becoming more thicker which makes more of the suns radiation (heat) stay in the earth; as a result, this is increasing the earth's temperature.
The subject is geography :)
Explanation:
An absorption line will appear in a spectrum if an absorbing material is placed between a source and the observer.
A comet. It’s a smaller celestial body that’s composed of mainly ice and dust.
