Saturday, October 3, 2009

Harvest Moon and More!

If you were out tonight, it was hard to miss the full moon. We were supposed to get rain, and, in fact, the humidity is a little high and there are scattered clouds, but it is clear overhead. Since this is the full moon nearest the autumnal equinox that occurred a week and a half ago, it is called the harvest moon. Supposedly it allows farmers to work into the evening with the benefit of light from the full moon. In addition, since the the ecliptic, thus the path of the moon is moving northward, in the northern hemisphere the moon rises only 20-30 minutes later each night, instead of the normal 40-50 minutes, providing additional evening illumination. This snapshot was taken within 30 minutes of being full, about 10:30 Tucson time (full moon was about 11pm). It was taken with an 8" Celestron and Canon XSi (ISO 400) at prime focus mounted on a tripod (no tracking). Exposure was 1/1250 second, thus freezing the moon's apparent motion due to the rotation of the earth.

There is news on the moon! In a few days, the morning of 9 October 4:31am Tucson time (11:31 UT) NASA is sending an impactor into a permanently shadowed crater near the Moon's south pole in an attempt to detect water on the moon. It is very unlikely anything will be visible to the unaided eye, but they are thinking the expected plume will be visible in a 10"-12" (25cm-30cm) telescope. For information regarding observing the impact, or for links to the mision and finder charts, go to their observation page.

While out, I also pointed at Jupiter, bright and high just west of south. All 4 of the moons discovered by Galileo 400 years ago were visible in this exposure - same info as above except 1/60 second exposure(click the image to enlarge). From left to right is Europa, the overexposed disk of Jupiter, the innermost moon Io, Ganymede and the outermost Callisto. It is really hard to show the moons and still show details on Jupiter's disk, but in reality, a DSLR is not the best way to image the planets, especially without tracking! Nowdays, amateurs are doing amazing things with video clips of the planet with small camera or even a webcam, then stacking hundreds or thousands of images to average out the atmospheric turbulence. Check out the efforts of my friend Tom Polakis a couple weeks ago - astounding results with a 10" (25cm) telescope. Check it out, as well as his other planetary images.

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