NASAのインスタグラム(nasagoddard) - 12月22日 01時00分

Like a bright ornament in a holiday wreath, this bright star decorates its surrounding nebula with waves of light. This image from @NASAHubble shows RS Puppis, a Cepheid variable star which rhythmically brightens and dims over a six-week cycle. Its average intrinsic brightness is 15,000 times greater than the Sun's luminosity.

The nebula flickers in brightness as pulses of light from the Cepheid propagate outwards. Hubble took a series of photos of light flashes rippling across the nebula in a phenomenon known as a "light echo." Even though light travels through space fast enough to span the gap between Earth and the Moon in a little over a second, the nebula is so large that reflected light can actually be photographed crossing the nebula.

Image credit: NASA, ESA and the Hubble Heritage Team (STScI/AURA) – Hubble/Europe Collaboration; Acknowledgement: H. Bond (STScI and Pennsylvania State University)

#space #Hubble #HST #star #astronomy #telescope #nebula

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