Planets, moons and clusters

by David Kingsley


Have gotten out in backyard several times over the last few weeks with 105 mm refractor or 7 inch Starmaster.

The clear highlight has been Saturn hovering among the southern reaches of M44. Through binoculars, Saturn looks like it is passing just underneath the open cluster. However in any telescope eyepiece giving a 1 degree field or more, Saturn is beautifully intermingled with both its own moons and with cluster stars. The extra aperture turns Saturn into a minicluster itself, the tiny solar system splashed against the backdrop of a star cluster that is 20 light years across, but 600 light years away. Thanks to Mark Wagner for pointing out the proximity of Saturn and M44 when he saw them in a finder scope a couple weeks ago, and to Randy and Jamie for the recent binocular reports.

For those who are using Astroplanner, try the following experiment. Add Saturn to your observing list. Go to Field of view and select a Telrad sized field with APDSO, Bright Stars, and Tycho II stars all turned on. Now toggle on the " Proper Motion" display option. The M44 cluster is easy to pick out by looking at the common proper motion tracks of both bright and faint stars in the field. The Beehive cluster extends further than you'd think from just the brightest stars, and clearly overlaps the current position of Saturn. The proper motion display is just one of several interesting features in the Astroplanner program. I've tried lots of astronomy software over the years but Astroplanner is the most useful package I have found for hunting down obscure objects and assembling custom observing lists.

I stumbled upon another "solar system meets cluster" juxtaposition last night while going for a walk around 11:30 pm. Thin hazy clouds covered much of the western sky but I took a pair of 15x45 binoculars with me anyway. I looked over at the waxing first quarter moon and was surprised to see that the moon was beginning to pass in front of the Pleiades! This could have been a very interesting event to watch through a telescope, with the dark unlit side of the moon progressively blotting out more and more stars of one of the prettiest clusters in the sky. However there were so many clouds building up that I decided the binocular view would have to do. I checked a recent Sky and Telescope article to see when the next such event would be visible from the west coast. Unfortunately last night was one of the best lunar occultations of M45 for the entire year from the west coast. On Saturday April 1st, a 16% waxing moon slides over M45 about 5 pm in the afternoon. If the skies are clear that Saturday, I might try setting up a scope and seeing if I can watch a daylight/dusk meeting of the moon and M45.


Posted on sf-bay-tac Feb 06, 2006 22:40:12 PT
Converted by report.pm 1.2 Feb 27, 2006 19:48:05 PT