来自MSN3 个月
What Is a Nebula?
Hubble Telescope image of the Horsehead Nebula. Credit: T.A.Rector (NOIRLab/NSF/AURA) & Hubble Heritage Team (STScI/AURA/NASA) Nebulae are all but impossible to spot in the night sky, but you'd ...
Helix Nebula: This a planetary nebula, which is formed when a star like the Sun runs out of fuel, expands and its outer layers puff off, and then the core of the star shrinks. Orion Nebula ...