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 Earth tend to turn to the right because of the coriolis effect. As a result, large-scale horizontal flows of air or water tend to form clockwise-turning gyres. These are best seen in ocean circulation patterns in the North Atlantic and North Pacific oceans. For the same reason, flows of air down toward the northern surface of the Earth tend to spread across the surface in a clockwise pattern. Thus, clockwise air circulation is characteristic of high pressure weather cells in the Northern Hemisphere. Conversely, air rising from the northern surface of the Earth (creating a region of low pressure) tends