星 places 生 (to be born — which you learned) under 日 (sun): the little lights born when the sun retires. Ancient forms drew three tiny suns scattered — a night sky in miniature.
星 lights the calendar and the red carpet alike: 星期 (week — 'star period'), 明星 ('bright star' — a celebrity), 星星 (the doubled, affectionate word for stars kids use). Chinese astronomy mapped 28 lunar mansions of 星 millennia ago; today 五星 (five stars) rates hotels and flags the national emblem. From Polaris to pop idols, 星 covers everything that shines above the crowd.
Born 生 from the sun 日 after dark — the STARS.
明星 'bright star' meant Venus in classical texts; now it means celebrities — same sky, new gods.