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Mercury, ISON and Spica

Submitter: Ramon Navarro
Description: In the morning of November 20th 2013 the skies cleared up over The Netherlands (at least for Dutch Standards). Finally this gave an opportunity to picture planet Mercury and comet ISON together with the star Spica.

This image was taken from Meppel in The Netherlands in South Eastern direction at 7.52AM, which is 1 hour and 15 minutes before sunrise using a Canon 1100D with a 55mm lens. Exposure settings were 5 seconds at f/5.6 and ISO 1000. Mercury, ISON and Spica are respectively 5°, 8° and 13.5° above the horizon.

Because ISON is only 8 degrees above the horizon it appears about 10 times dimmer than if it would have been high in the sky. This is due to the increased airmass close to the horizon. In this picture ISON is observed through airmass 7, thus observed through 7 times the amount of air relative to a star that is directly overhead (at zenith). Unfortunately the comets tail is not visible due to twilight and moonlight.

This is one of the last times that comet ISON is visible before its approach of perihelion on November 28; the point of closest approach of the Sun. If the comet survives the intense baking of the sun it is expected to return to the night sky glorious and with a bright tail early December. By the time of the holiday season ISON will be visible the entire night. Let's hope for some spectacular fireworks!
Copyright: Ramon Navarro
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