In the Southern Hemisphere of our Universe is a bright super star called RS Puppis. This flickering star lights and darkens rhythmically throughout a cycle that lasts six weeks, causing a phenomenon known as "light echoes."
The images that exist of the star RS Puppis have been obtained by the NASA Hubble Space Telescope. Thanks to Hubble, we know that Puppis is ten times more massive than our Sun, 200 times larger and 15,000 times brighter. It is one of the brightest stars in the Cepheid class of variables.
We can see RS Puppis in the center of the image surrounded by a cloud of reflective dust that illuminates the star itself. This nebula emits pulses of light from the star that spread outward. Although light travels through space fast enough to cover the distance between Earth and the Moon in just over a second, the Puppis nebula is so large that the reflected light can be photographed through it.
By studying the fluctuation of light in RS Puppis and recording the reflections of pulses of light moving through the nebula, astronomers have been able to measure the light echoes of the star. This measurement has served to obtain a very precise distance from Puppis to Earth, which is 6,500 light-years, with a margin of error of only 1 percent.
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