
The night sky is the appearance of like , , and the , which are visible in a clear between and , when the is below the . Natural light sources in a night sky include , , and , depending on location and timing. light up the skies above the . Occasionally, a large from the Sun or simply high levels of may extend the phenomenon toward the

Renewable energy (or green energy) is from that are replenished on a . The most widely used renewable energy types are , , and . and are also significant in some countries. Some also consider , although this is controversial. Rene.

, known as renewable resources, are replaced by persistent in the . There are and reoccurring renewables, and , which are utilized during a across a certain amount of time, and can be harnessed for any number of cycles.

According to a 2017 (NRCAN) document, renewable energy refers to energy sources that are replenished naturally and at a rate that is equal to or faster than the rate at which they are utilized. A variety of techniques and equipment in the environmental and clean technologies (ECT) sector have been developed and used to harness renewable resources for energy production.