Night sky night sky. Aircraft are also visible at night, distinguishable at a distance from other objects because their lights blink. Night sky The term night sky, usually associated with astronomy from Earth, refers to the nighttime appearance of celestial objects like stars, planets, and the Moon, which are visible in a clear sky between sunset and sunrise, when the Sun is below the horizon. Natural light sources in a night sky include moonlight, starlight, and airglow, depending on location and timing. Aurorae light up the skies above the polar circles. Occasionally, a large coronal mass ejection from the Sun or simply
Northern Hemisphere the North Pole, which is the middle of the Northern Hemisphere. Between the Arctic Circle and the Tropic of Cancer lies the Northern temperate zone. The changes in these regions between summer and winter are generally mild, rather than extreme hot or cold. However, a temperate climate can have very unpredictable weather. Tropical regions (between the Tropic of Cancer and the Equator) are generally hot all year round and tend to experience a rainy season during the summer months, and a dry season during the winter months. In the Northern Hemisphere, objects moving across or above the surface of the