A couple of other science-ee notes for star parties this week and Venus-Saturn: 5) Inferior planets exhibit maximum enlongation with respect to a superior planet; Superior planets do not show maximum enlongation. Venus past maximum enlongation about a month ago. Venus will reach maximum brightness in about a week. Maximum elongation means the apparent position of Venus (from Earth's orbit) is the furthest that it gets from the Sun. For the next couple months, Venus will appear to travel closer to the twlight setting Sun. Near maximum elongation, Venus closer to Earth. The combination of its crescent phase and proximity to the Earth result in its maximum brightness. Because it is a superior planet, Saturn does not display maximum elongation relative to the Earth. Conversely, if the Cassini orbiter were to look back at Earth and Venus, both would be near maximum elongation as seen from Saturn. The JPL/NASA solar system planectia can be used to display a "from above" image of the solar system to show relative planet positions. http://space.jpl.nasa.gov/ Display the "Solar System" from "Above" and set the "field of view" to 2 degrees. A 3-D diagram can be generated using the NASA-JPL small body orbit simulator. http://neo.jpl.nasa.gov/orbits/ Enter "Vesta" in the object box to generate a suitable display. Suitable diagrams also are published each month in Sky & Telescope. 6) There unmanned orbiters at both Saturn and Venus returning images. Enjoyment of Earth-based visual observing of Saturn and Venus can be enhanced by follow-up viewing of current oribter images of those planets. Saturn - Cassini http://ciclops.org/index.php?flash=1&flash=1&js=1 http://saturn.jpl.nasa.gov/home/index.cfm http://www.esa.int/SPECIALS/Cassini-Huygens/index.html Venus - Venus Express http://www.esa.int/SPECIALS/Venus_Express/index.html NASA Cassini image returns are closer to real time. Like other ESA missions (SMART-1), Venus Express image postings are made infrequently, but are available. Here's an amateur image by Rob Johnson (posted on sci.astro.amateur) of Saturn and Venus together that illustrates the ecliptic plane note (item no. 3) up-thread: http://www.whim.org/nebula/astro/vsalign20070630.html - Kurt _______________________________________________ Sent via CSolutions - http://www.csolutions.net