星相是什么意思 每日星相:Daily Astronomy(5)

每日星相:Daily Astronomy(5)  

Sometimes it's night on the ground but day in the air. As the Earth rotatestoeclipse the Sun
sunset rises up from the ground. Therefore
at sunset on the ground
sunlight still shines on clouds above. Under usual circumstances
a pretty sunset might be visible
but unusual noctilucent clouds float so high up they can be seen well after dark. Normally too dim to be seen
they may bee visible at sunset during late summer when illuminated by sunlight from below. Noctilucent clouds are the highest clouds known and thought to be part of polar mesospheric clouds. Pictured above earlier this month
a neork of noctilucent clouds cast an eeriewhite glow after dusk
above the the city of Edmonton
in Alberta
Canada. Much about noctilucent clouds has been discovered only over the past few years
while how they form and evolve remains a topic of active research.
重点注释：
rotate vt. & vi. 旋转；转动
eclipse n. 日食；月食
noctilucent adj. 生物发光的
夜发光的
eerie adj. (因阴森怪诞而)引起恐惧的;可怕的; 怪异的; 神祕的; 令人恐怖的
evolve vt. & vi. 演变; 进化