It’s that time of year when the night times shrinknoctilucent (night-shining) clouds. These may be seen low above the northwest horizon 90-120 minutes after sunset or a similar time before sunrise, low above the northeast horizon. They appear to glow against the deep twilight and often have a delicate, net-like appearance. Although not ideal in terms of timing, they are easy to observe without any equipment (see page 46).
