NASA’s Hubble Space Telescope has captured a stunning view of Comet Siding Spring as it made a close flyby of Mars, showing just how close the comet came to the Red Planet.
The photo is actually a composite of images combined to show the distance between the two celestial bodies during their close encounter. Comet Siding Spring made its closest approach to Mars on Oct. 19 at 2:28 p.m. EDT at a distance of approximately 87,000 miles, less than half the distance between Earth and the moon. [WATCH REPLAY: Webcast Of Comet Siding Spring's Flyby Of Mars]
The image of the comet is a composite of exposures taken by Hubble between Oct. 18, 8:06 a.m. and Oct. 19, 11:17 p.m. The space telescope captured a separate image of Mars at 10:37 p.m. on Oct. 18, which was then combined with the image of the comet. The stars in the background were created based on data from ground-based telescopes provided by the Palomar Digital Sky Survey.
Mars and the comet could not be imaged at the same time by the telescope because the Red Planet is approximately 10,000 brighter than Comet Siding Spring. The two bodies were also both moving, meaning they could not be captured within the same exposure without one suffering from motion blur.