Transcript: We can use relative brightness to show how bright various objects in the night sky are compared to the limits of technologies we use to observe the sky. In units where Vega, the bright star, is one unit of apparent brightness, the Sun is 40 billion times brighter. The full moon is 100 thousand times brighter than Vega, and for reference a 100 watt light bulb at a distance of 100 meters is 27,700 times brighter than Vega. Venus at its brightest is about 60 times brighter than the star Vega, Mars 12 times brighter, and Jupiter about 4 times brighter. The bright star Sirius is 3.5 times brighter than Vega. The limit of observation in cities with the naked eye, in units where Vega is one, is 0.025. That is, that we can see 40 times fainter than Vega. In a remote rural area the limit may be ten times less than that, 400 times fainter than Vega. Neptune on the same scale in the same units is 0.0008, a thousand times fainter than the bright star Vega. The limit of binoculars is about 6 timse 10-6 in these units, 100 thousand times fainter than the bright stars, and the limit of the Hubble Space Telescope in the same relative units is 3 times 10-12. The Hubble Space Telescope can see about a trillion times fainter than the brightest star in the sky.