|
This picture of the western and northern sky was exposed for 30 minutes on the evening of Thursday 4 April 2002. The exposure was started approximately half an hour after the end of astronomical twilight when the sun was more than 18 degrees below the horizon. The bright yellow light is sunlight that is reflected against small dust particles that float in the inner solar system. It is called zodiacal light because it is concentrated in the plane where the planets (and also Earth) rotate around the sun. More to the right of the picture the comet Ikeya-Zhang is visible. It has recently been close to the sun and its icy surface has melted somewhat, resulting in a blue tail of gas particles and a white tail of dust particles. Probably the dust that produces the zodiacal light also comes from comets that have been flying through the solar system since the beginning of our solar system.
Technical details: lens Nikkor 16 mm f/3.5, film Kodak Supra 800 ISO, exposure two negatives each exposed 15 minutes and combined with Picture window 3.0 at setting composite filter additive. Exposure started at 20:50 UT. Field of view is aproximately 140 x 90 degrees.
|
|
This picture shows the comet more in detail. The comet itself only measures about ten kilometers in diameter and is hidden in the clouds of water vapor and other gases that surround it. The tails probably are millions of kilometers long and are visible because sunlight reflects against them. To the lower right of the comet another fuzzy object is visible. This is our neighbor galaxy M31, the Andromeda galaxy. The apparent closeness of both objects is purely concidental: the light of the comet took less than an hour to reach us while the light of the Andromeda galaxy took more than a million years to reach Earth.
Technical details: lens Nikkor 50 mm f/1.4, film Kodak Supra 800 Iso, exposure two negatives each exposed 2 minutes and combined with Picture window 3.0 at setting composite filter additive. Exposure started at 22:00 UT. Height above the horizon of M31 is aproximately 5 degrees. Visibility was clear skies with haze due to SE wind from the mainland.
|
|
